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1.	Simoes, JFF, et al. (författare) Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study 2021 Ingår i: Anaesthesia. - : Wiley. - 1365-2044 .- 0003-2409. ; 76:11, s. 1454-1464 Tidskriftsartikel (refereegranskat)
2.	Keppler, M., et al. (författare) Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70 2018 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 617 Tidskriftsartikel (refereegranskat)abstract Context. Young circumstellar disks are the birthplaces of planets. Their study is of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features.Aims. In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of an embedded young planet and search for disk structures that may be the result of disk-planet interactions and other evolutionary processes.Methods. We analyse new and archival near-infrared images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo, and Gemini/NICI instruments in polarimetric differential imaging and angular differential imaging modes.Results. We detect a point source within the gap of the disk at about 195 mas (similar to 22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance. The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. The luminosity of the detected object is consistent with that of an L-type dwarf, but its IR colours are redder, possibly indicating the presence of warm surrounding material. Further, we confirm the detection of a large gap of similar to 54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than similar to 17 au in radius, and its position angle is consistent with that of the outer disk. The images of the outer disk show evidence of a complex azimuthal brightness distribution which is different at different wavelengths and may in part be explained by Rayleigh scattering from very small grains.Conclusions. The detection of a young protoplanet within the gap of the transition disk around PDS 70 opens the door to a so far observationally unexplored parameter space of planetary formation and evolution. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres, and evolutionary models.
3.	Nelson, G., et al. (författare) QUAREP-LiMi: A community-driven initiative to establish guidelines for quality assessment and reproducibility for instruments and images in light microscopy 2021 Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 284:1, s. 56-73 Tidskriftsartikel (refereegranskat)abstract A modern day light microscope has evolved from a tool devoted to making primarily empirical observations to what is now a sophisticated , quantitative device that is an integral part of both physical and life science research. Nowadays, microscopes are found in nearly every experimental laboratory. However, despite their prevalent use in capturing and quantifying scientific phenomena, neither a thorough understanding of the principles underlying quantitative imaging techniques nor appropriate knowledge of how to calibrate, operate and maintain microscopes can be taken for granted. This is clearly demonstrated by the well-documented and widespread difficulties that are routinely encountered in evaluating acquired data and reproducing scientific experiments. Indeed, studies have shown that more than 70% of researchers have tried and failed to repeat another scientist's experiments, while more than half have even failed to reproduce their own experiments. One factor behind the reproducibility crisis of experiments published in scientific journals is the frequent underreporting of imaging methods caused by a lack of awareness and/or a lack of knowledge of the applied technique. Whereas quality control procedures for some methods used in biomedical research, such as genomics (e.g. DNA sequencing, RNA-seq) or cytometry, have been introduced (e.g. ENCODE), this issue has not been tackled for optical microscopy instrumentation and images. Although many calibration standards and protocols have been published, there is a lack of awareness and agreement on common standards and guidelines for quality assessment and reproducibility. In April 2020, the QUality Assessment and REProducibility for instruments and images in Light Microscopy (QUAREP-LiMi) initiative was formed. This initiative comprises imaging scientists from academia and industry who share a common interest in achieving a better understanding of the performance and limitations of microscopes and improved quality control (QC) in light microscopy. The ultimate goal of the QUAREP-LiMi initiative is to establish a set of common QC standards, guidelines, metadata models and tools, including detailed protocols, with the ultimate aim of improving reproducible advances in scientific research. This White Paper (1) summarizes the major obstacles identified in the field that motivated the launch of the QUAREP-LiMi initiative; (2) identifies the urgent need to address these obstacles in a grassroots manner, through a community of stakeholders including, researchers, imaging scientists, bioimage analysts, bioimage informatics developers, corporate partners, funding agencies, standards organizations, scientific publishers and observers of such; (3) outlines the current actions of the QUAREP-LiMi initiative and (4) proposes future steps that can be taken to improve the dissemination and acceptance of the proposed guidelines to manage QC. To summarize, the principal goal of the QUAREP-LiMi initiative is to improve the overall quality and reproducibility of light microscope image data by introducing broadly accepted standard practices and accurately captured image data metrics.
4.	Langlois, M., et al. (författare) The SPHERE infrared survey for exoplanets (SHINE) : II. Observations, data reduction and analysis, detection performances, and initial results 2021 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 651 Tidskriftsartikel (refereegranskat)abstract Context. In recent decades, direct imaging has confirmed the existence of substellar companions (exoplanets or brown dwarfs) on wide orbits (>10 au) around their host stars. In striving to understand their formation and evolution mechanisms, in 2015 we initiated the SPHERE infrared survey for exoplanets (SHINE), a systematic direct imaging survey of young, nearby stars that is targeted at exploring their demographics.Aims. We aim to detect and characterize the population of giant planets and brown dwarfs beyond the snow line around young, nearby stars. Combined with the survey completeness, our observations offer the opportunity to constrain the statistical properties (occurrence, mass and orbital distributions, dependency on the stellar mass) of these young giant planets.Methods. In this study, we present the observing and data analysis strategy, the ranking process of the detected candidates, and the survey performances for a subsample of 150 stars that are representative of the full SHINE sample. Observations were conducted in a homogeneous way between February 2015 and February 2017 with the dedicated ground-based VLT/SPHERE instrument equipped with the IFS integral field spectrograph and the IRDIS dual-band imager, covering a spectral range between 0.9 and 2.3 μm. We used coronographic, angular, and spectral differential imaging techniques to achieve the best detection performances for this study, down to the planetary mass regime.Results. We processed, in a uniform manner, more than 300 SHINE observations and datasets to assess the survey typical sensitivity as a function of the host star and of the observing conditions. The median detection performance reached 5σ-contrasts of 13 mag at 200 mas and 14.2 mag at 800 mas with the IFS (YJ and YJH bands), and of 11.8 mag at 200 mas, 13.1 mag at 800 mas, and 15.8 mag at 3 as with IRDIS in H band, delivering one of the deepest sensitivity surveys thus far for young, nearby stars. A total of sixteen substellar companions were imaged in this first part of SHINE: seven brown dwarf companions and ten planetary-mass companions.These include two new discoveries, HIP 65426 b and HIP 64892 B, but not the planets around PDS70 that had not been originally selected for the SHINE core sample. A total of 1483 candidates were detected, mainly in the large field of view that characterizes IRDIS. The color-magnitude diagrams, low-resolution spectrum (when available with IFS), and follow-up observations enabled us to identify the nature (background contaminant or comoving companion) of about 86% of our subsample. The remaining cases are often connected to crowded-field follow-up observations that were missing. Finally, even though SHINE was not initially designed for disk searches, we imaged twelve circumstellar disks, including three new detections around the HIP 73145, HIP 86598, and HD 106906 systems.Conclusions. Nowadays, direct imaging provides a unique opportunity to probe the outer part of exoplanetary systems beyond 10 au to explore planetary architectures, as highlighted by the discoveries of: one new exoplanet, one new brown dwarf companion, and three new debris disks during this early phase of SHINE. It also offers the opportunity to explore and revisit the physical and orbital properties of these young, giant planets and brown dwarf companions (relative position, photometry, and low-resolution spectrum in near-infrared, predicted masses, and contrast in order to search for additional companions). Finally, these results highlight the importance of finalizing the SHINE systematic observation of about 500 young, nearby stars for a full exploration of their outer part to explore the demographics of young giant planets beyond 10 au and to identify the most interesting systems for the next generation of high-contrast imagers on very large and extremely large telescopes.
5.	Chauvin, G., et al. (författare) Discovery of a warm, dusty giant planet around HIP 65426 2017 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 605 Tidskriftsartikel (refereegranskat)abstract Aims. The SHINE program is a high-contrast near-infrared survey of 600 young, nearby stars aimed at searching for and characterizing new planetary systems using VLT/SPHERE's unprecedented high-contrast and high-angular-resolution imaging capabilities. It is also intended to place statistical constraints on the rate, mass and orbital distributions of the giant planet population at large orbits as a function of the stellar host mass and age to test planet-formation theories.Methods. We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426. It is a member of the similar to 17 Myr old Lower Centaurus-Crux association. Results. At a separation of 830 mas (92 au projected) from the star, we detect a faint red companion. Multi-epoch observations confirm that it shares common proper motion with HIP 65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2 mu m indicate a warm, dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs. Hot-start evolutionary models predict a luminosity consistent with a 6-12 M-Jup, T-eff = 1300-1600K and R = 1.5 +/- 0.1 R-Jup giant planet. Finally, the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log(g) = 4.0-5.0 with smaller radii (1.0-1.3 R-Jup).Conclusions. Given its physical and spectral properties, HIP 65426 b occupies a rather unique placement in terms of age, mass, and spectral-type among the currently known imaged planets. It represents a particularly interesting case to study the presence of clouds as a function of particle size, composition, and location in the atmosphere, to search for signatures of non-equilibrium chemistry, and finally to test the theory of planet formation and evolution.
6.	Lagrange, A. -M., et al. (författare) Post-conjunction detection of beta Pictoris b with VLT/SPHERE 2019 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 621 Tidskriftsartikel (refereegranskat)abstract Context. With an orbital distance comparable to that of Saturn in the solar system, beta Pictoris b is the closest (semi-major axis similar or equal to 9 au) exoplanet that has been imaged to orbit a star. Thus it offers unique opportunities for detailed studies of its orbital, physical, and atmospheric properties, and of disk-planet interactions. With the exception of the discovery observations in 2003 with NaCo at the Very Large Telescope (VLT), all following astrometric measurements relative to beta Pictoris have been obtained in the southwestern part of the orbit, which severely limits the determination of the planet's orbital parameters.Aims. We aimed at further constraining beta Pictoris b orbital properties using more data, and, in particular, data taken in the northeastern part of the orbit.Methods. We used SPHERE at the VLT to precisely monitor the orbital motion of beta beta Pictoris b since first light of the instrument in 2014.Results. We were able to monitor the planet until November 2016, when its angular separation became too small (125 mas, i.e., 1.6 au) and prevented further detection. We redetected beta Pictoris b on the northeast side of the disk at a separation of 139 mas and a PA of 30 degrees in September 2018. The planetary orbit is now well constrained. With a semi-major axis (sma) of a = 9.0 +/- 0.5 au (1 sigma), it definitely excludes previously reported possible long orbital periods, and excludes beta Pictoris b as the origin of photometric variations that took place in 1981. We also refine the eccentricity and inclination of the planet. From an instrumental point of view, these data demonstrate that it is possible to detect, if they exist, young massive Jupiters that orbit at less than 2 au from a star that is 20 pc away.
7.	Cheetham, A., et al. (författare) Discovery of a brown dwarf companion to the star HIP 64892 2018 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 615 Tidskriftsartikel (refereegranskat)abstract We report the discovery of a bright, brown dwarf companion to the star HIP 64892, imaged with VLT/SPHERE during the SHINE exoplanet survey. The host is a B9.5V member of the Lower-Centaurus-Crux subgroup of the Scorpius Centaurus OB association. The measured angular separation of the companion (1.2705 +/- 0.0023) corresponds to a projected distance of 159 +/- 12AU. We observed the target with the dual-band imaging and long-slit spectroscopy modes of the IRDIS imager to obtain its spectral energy distribution (SED) and astrometry. In addition, we reprocessed archival NACO L-band data, from which we also recover the companion. Its SED is consistent with a young (<30 Myr), low surface gravity object with a spectral type of M9 gamma +/- 1. From comparison with the BT-Settl atmospheric models we estimate an effective temperature of T-eff = 2600 +/- 100 K, and comparison of the companion photometry to the COND evolutionary models yields a mass of similar to 29-37 M-J at the estimated age of 16(-7)(+15) Myr for the system. The star HIP 64892 is a rare example of an extreme-mass ratio system (q similar to 0.01) and will be useful for testing models relating to the formation and evolution of such low-mass objects.
8.	Lacour, S., et al. (författare) The mass of β Pictoris c from β Pictoris b orbital motion 2021 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 654 Tidskriftsartikel (refereegranskat)abstract Aims. We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet.Methods. We combined previous astrometry of β Pictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion of β Pictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet, β Pictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations.Results. From the astrometry of planet b only, we can (i) detect the presence of β Pictoris c and (ii) constrain its mass to 10.04(-3.10)(+4.53) M-Jup. If one adds the astrometry of β Pictoris c, the mass is narrowed down to 9.15(-1.06)(+1.08) M-Jup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89(-0.75)(+0.75) M-Jup. With a semimajor axis of 2.68 +/- 0.02 au, a period of 1221 +/- 15 days, and an eccentricity of 0.32 +/- 0.02, the orbital parameters of β Pictoris c are now constrained as precisely as those of β Pictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets' dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.
9.	Bonavita, M., et al. (författare) New binaries from the SHINE survey 2022 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 663 Tidskriftsartikel (refereegranskat)abstract We present the multiple stellar systems observed within the SpHere INfrared survey for Exoplanet (SHINE). SHINE searched for sub-stellar companions to young stars using high contrast imaging. Although stars with known stellar companions within the SPHERE field of view (< 5.5 arcsec) were removed from the original target list, we detected additional stellar companions to 78 of the 463 SHINE targets observed so far. Twenty-seven per cent of the systems have three or more components. Given the heterogeneity of the sample in terms of observing conditions and strategy, tailored routines were used for data reduction and analysis, some of which were specifically designed for these datasets. We then combined SPHERE data with literature and archival data, TESS light curves, and Gaia parallaxes and proper motions for an accurate characterisation of the systems. Combining all data, we were able to constrain the orbits of 25 systems. We carefully assessed the completeness of our sample for separations between 50–500 mas (corresponding to periods of a few years to a few decades), taking into account the initial selection biases and recovering part of the systems excluded from the original list due to their multiplicity. This allowed us to compare the binary frequency for our sample with previous studies and highlight interesting trends in the mass ratio and period distribution. We also found that, when such an estimate was possible, the values of the masses derived from dynamical arguments were in good agreement with the model predictions. Stellar and orbital spins appear fairly well aligned for the 12 stars that have enough data, which favours a disk fragmentation origin. Our results highlight the importance of combining different techniques when tackling complex problems such as the formation of binaries and show how large samples can be useful for more than one purpose.
10.	Bonnefoy, M., et al. (författare) The GJ 504 system revisited Combining interferometric, radial velocity, and high contrast imaging data 2018 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 618 Tidskriftsartikel (refereegranskat)abstract Context. The G-type star GJ504A is known to host a 3-35 M-Jup companion whose temperature, mass, and projected separation all contribute to making it a test case for planet formation theories and atmospheric models of giant planets and light brown dwarfs. Aims. We aim at revisiting the system age, architecture, and companion physical and chemical properties using new complementary interferometric, radial-velocity, and high-contrast imaging data. Methods. We used the CHARA interferometer to measure GJ504A's angular diameter and obtained an estimation of its radius in combination with the HIPPARCOS parallax. The radius was compared to evolutionary tracks to infer a new independent age range for the system. We collected dual imaging data with IRDIS on VLT/SPHERE to sample the near-infrared (1.02-2.25 mu m) spectral energy distribution (SED) of the companion. The SED was compared to five independent grids of atmospheric models (petitCODE, Exo-REM, BT-SETTL, Morley et al., and ATMO) to infer the atmospheric parameters of GJ 504b and evaluate model-to-model systematic errors. In addition, we used a specific model grid exploring the effect of different C/O ratios. Contrast limits from 2011 to 2017 were combined with radial velocity data of the host star through the MESS2 tool to define upper limits on the mass of additional companions in the system from 0.01 to 100 au. We used an MCMC fitting tool to constrain the companion's orbital parameters based on the measured astrometry, and dedicated formation models to investigate its origin. Results. We report a radius of 1.35 +/- 0.04 R-circle dot for GJ504A. The radius yields isochronal ages of 21 +/- 2 Myr or 4.0 +/- 1.8 Gyr for the system and line-of-sight stellar rotation axis inclination of 162.4(-4.3)(+3.8) degrees or 18.6(-3.8)(+4.3) degrees. We re-detect the companion in the Y2, Y3, J3, H2, and K1 dual-band images. The complete 1-4 mu m SED shape of GJ504b is best reproduced by T8-T9.5 objects with intermediate ages (<= 1.5Gyr), and/or unusual dusty atmospheres and/or super-solar metallicities. All atmospheric models yield T-eff = 550 +/- 50 K for GJ504b and point toward a low surface gravity (3.5-4.0 dex). The accuracy on the metallicity value is limited by model-to-model systematics; it is not degenerate with the C/O ratio. We derive log L/L-circle dot = 6.15 +/- 0.15 dex for the companion from the empirical analysis and spectral synthesis. The luminosity and T-eff yield masses of M = 1.3(-0.3)(+0.6) M-Jup and M = 23(-9)(+10) M-Jup for the young and old age ranges, respectively. The semi-major axis (sma) is above 27.8 au and the eccentricity is lower than 0.55. The posterior on GJ 504b's orbital inclination suggests a misalignment with the rotation axis of GJ 504A. We exclude additional objects (90% prob.) more massive than 2.5 and 30 M-Jup with semi-major axes in the range 0.01-80 au for the young and old isochronal ages, respectively. Conclusions. The mass and semi-major axis of GJ 504b are marginally compatible with a formation by disk-instability if the system is 4 Gyr old. The companion is in the envelope of the population of planets synthesized with our core-accretion model. Additional deep imaging and spectroscopic data with SPHERE and JWST should help to confirm the possible spin-orbit misalignment and refine the estimates on the companion temperature, luminosity, and atmospheric composition.
11.	Lagrange, A. M., et al. (författare) Unveiling the beta Pictoris system, coupling high contrast imaging, interferometric, and radial velocity data 2020 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 642 Tidskriftsartikel (refereegranskat)abstract Context. The nearby and young beta Pictoris system hosts a well resolved disk, a directly imaged massive giant planet orbiting at similar or equal to 9 au, as well as an inner planet orbiting at similar or equal to 2.7 au, which was recently detected through radial velocity (RV). As such, it offers several unique opportunities for detailed studies of planetary system formation and early evolution.Aims. We aim to further constrain the orbital and physical properties of beta Pictoris b and c using a combination of high contrast imaging, long base-line interferometry, and RV data. We also predict the closest approaches or the transit times of both planets, and we constrain the presence of additional planets in the system.Methods. We obtained six additional epochs of SPHERE data, six additional epochs of GRAVITY data, and five additional epochs of RV data. We combined these various types of data in a single Markov-chain Monte Carlo analysis to constrain the orbital parameters and masses of the two planets simultaneously. The analysis takes into account the gravitational influence of both planets on the star and hence their relative astrometry. Secondly, we used the RV and high contrast imaging data to derive the probabilities of presence of additional planets throughout the disk, and we tested the impact of absolute astrometry.Results. The orbital properties of both planets are constrained with a semi-major axis of 9.8 0.4 au and 2.7 +/- 0.02 au for b and c, respectively, and eccentricities of 0.09 +/- 0.1 and 0.27 +/- 0.07, assuming the HIPPARCOS distance. We note that despite these low fitting error bars, the eccentricity of beta Pictoris c might still be over-estimated. If no prior is provided on the mass of beta Pictoris b, we obtain a very low value that is inconsistent with what is derived from brightness-mass models. When we set an evolutionary model motivated prior to the mass of beta Pictoris b, we find a solution in the 10-11 M-Jup range. Conversely, beta Pictoris c's mass is well constrained, at 7.8 +/- 0.4 M-Jup, assuming both planets are on coplanar orbits. These values depend on the assumptions on the distance of the beta Pictoris system. The absolute astrometry HIPPARCOS-Gaia data are consistent with the solutions presented here at the 2 sigma level, but these solutions are fully driven by the relative astrometry plus RV data. Finally, we derive unprecedented limits on the presence of additional planets in the disk. We can now exclude the presence of planets that are more massive than about 2.5 M-Jup closer than 3 au, and more massive than 3.5 M-Jup between 3 and 7.5 au. Beyond 7.5 au, we exclude the presence of planets that are more massive than 1-2 M-Jup.Conclusions. Combining relative astrometry and RVs allows one to precisely constrain the orbital parameters of both planets and to give lower limits to potential additional planets throughout the disk. The mass of beta Pictoris c is also well constrained, while additional RV data with appropriate observing strategies are required to properly constrain the mass of beta Pictoris b.
12.	Sissa, E., et al. (författare) High-contrast study of the candidate planets and protoplanetary disk around HD 100546 2018 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 619 Tidskriftsartikel (refereegranskat)abstract The nearby Herbig Be star HD 100546 is known to be a laboratory for the study of protoplanets and their relation with the circum stellar disk, which is carved by at least two gaps. We observed the HD 100546 environment with high-contrast imaging exploiting several different observing modes of SPHERE, including data sets with and without coronagraphs, dual band imaging, integral field spectroscopy and polarimetry. The picture emerging from these different data sets is complex. Flux-conservative algorithm images clearly show the disk up to 200 au. More aggressive algorithms reveal several rings and warped arms that are seen overlapping the main disk. Some of these structures are found to lie at considerable height over the disk mid-plane at about 30 au. Our images demon-strate that the brightest wings close to the star in the near side of the disk are a unique structure, corresponding to the outer edge of the intermediate disk at similar to 40 au. Modeling of the scattered light from the disk with a geometrical algorithm reveals that a moderately thin structure (H/r = 0.18 at 40 au) can well reproduce the light distribution in the flux-conservative images. We suggest that the gap between 44 and 113 au spans between the 1:2 and 3:2 resonance orbits of a massive body located at similar to 70 au, which might coincide with the candidate planet HD 100546b detected with previous thermal infrared (IR) observations. In this picture, the two wings can be the near side of a ring formed by disk material brought out of the disk at the 1:2 resonance with the same massive object. While we find no clear evidence confirming detection of the planet candidate HD 100546c in our data, we find a diffuse emission close to the expected position of HD 100546b. This source can be described as an extremely reddened substellar object surrounded by a dust cloud or its circumplanetary disk. Its astrometry is broadly consistent with a circular orbital motion on the disk plane, a result that could be confirmed with new observations. Further observations at various wavelengths are required to fully understand the complex phenomenology of HD 100546.
13.	Chauvin, G., et al. (författare) Investigating the young solar system analog HD 95086 A combined HARPS and SPHERE exploration 2018 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 617 Tidskriftsartikel (refereegranskat)abstract Context. HD 95086 (A8V, 17 Myr) hosts a rare planetary system for which a multi-belt debris disk and a giant planet of 4-5 Mjup have been directly imaged.Aims. Our study aims to characterize the global architecture of this young system using the combination of radial velocity and direct imaging observations. We want to characterize the physical and orbital properties of HD 95086 b, search for additional planets at short and wide orbits and image the cold outer debris belt in scattered light.Methods. We used HARPS at the ESO 3.6 m telescope to monitor the radial velocity of HD 95086 over two years and investigate the existence of giant planets at less than 3 au orbital distance. With the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE at VLT, we imaged the faint circumstellar environment beyond 10 au at six epochs between 2015 and 2017.Results. We do not detect additional giant planets around HD 95086. We identify the nature (bound companion or background contaminant) of all point-like sources detected in the IRDIS field of view. None of them correspond to the ones recently discovered near the edge of the cold outer belt by ALMA. HD 95086 b is resolved for the first time in J-band with IFS. Its near-infrared spectral energy distribution is well fitted by a few dusty and/or young L7-L9 dwarf spectral templates. The extremely red 1-4 mu m spectral distribution is typical of low-gravity objects at the L/T spectral type transition. The planet's orbital motion is resolved between January 2015 and May 2017. Together with past NaCo measurements properly re-calibrated, our orbital fitting solutions favor a retrograde low to moderate-eccentricity orbit e = 0.2(-0.2)(+0.3), with a semi-major axis similar to 52 au corresponding to orbital periods of similar to 288 yr and an inclination that peaks at i = 141 degrees, which is compatible with a planet-disk coplanar configuration. Finally, we report the detection in polarimetric differential imaging of the cold outer debris belt between 100 and 300 au, consistent in radial extent with recent ALMA 1.3 mm resolved observations.
14.	Cheetham, A. C., et al. (författare) Spectral and orbital characterisation of the directly imaged giant planet HIP 65426 b 2019 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 622 Tidskriftsartikel (refereegranskat)abstract HIP 65426 b is a recently discovered exoplanet imaged during the course of the SPHERE-SHINE survey. Here we present new L' and M' observations of the planet from the NACO instrument at the VLT from the NACO-ISPY survey, as well as a new Y-H spectrum and K-band photometry from SPHERE-SHINE. Using these data, we confirm the nature of the companion as a warm, dusty planet with a mid-L spectral type. From comparison of its SED with the BT-Settl atmospheric models, we derive a best-fit effective temperature of T-eff = 1618 +/- 7 K, surface gravity log g = 3 : 78(-0.03)(+0.04) and radius R = 1.17 +/- 0.04 R-J (statistical uncertainties only). Using the DUSTY and COND isochrones we estimate a mass of 8 +/- 1 MJ. Combining the astrometric measurements from our new datasets and from the literature, we show the first indications of orbital motion of the companion (2.6 sigma significance) and derive preliminary orbital constraints. We find a highly inclined orbit (i = 107(+13)(-10) deg) with an orbital period of 800(+1200)(-400) yr. We also report SPHERE sparse aperture masking observations that investigate the possibility that HIP 65426 b was scattered onto its current orbit by an additional companion at a smaller orbital separation. From this data we rule out the presence of brown dwarf companions with masses greater than 16 M-J at separations larger than 3AU, significantly narrowing the parameter space for such a companion.
15.	Claudi, R., et al. (författare) SPHERE dynamical and spectroscopic characterization of HD142527B 2019 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 622 Tidskriftsartikel (refereegranskat)abstract Aims. HD142527 is one of the most frequently studied Herbig Ae/Be stars with a transitional disk that hosts a large cavity that is up to about 100 au in radius. For this reason, it has been included in the guaranteed time observation (GTO) SpHere INfrared survey for Exoplanets (SHINE) as part of the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) at the Very Large Telescope (VLT) in order to search for low-mass companions that might explain the presence of the gap. SHINE is a large survey within about 600 young nearby stars are observed with SPHERE with the aim to constrain the occurrence and orbital properties of the giant planet population at large (>5 au) orbital separation around young stars. Methods. We used the IRDIFS observing mode of SPHERE (IRDIS short for infrared dual imaging and spectrograph plus IFS or integral field spectrograph) without any coronagraph in order to search for and characterize companions as close as 30 mas of the star. Furthermore, we present the first observations that ever used the sparse aperture mask (SAM) for SPHERE both in IRDIFS and IRDIFS_EXT modes. All the data were reduced using the dedicated SPHERE pipeline and dedicated algorithms that make use of the principal component analysis (PCA) and reference differential imaging (RDI) techniques. Results. We detect the accreting low-mass companion HD142527B at a separation of 73 mas (11.4 au) from the star. No other companions with mass greater than 10 M-J are visible in the field of view of IFS (similar to 100 au centered on the star) or in the IRDIS field of view (similar to 400 au centered on the star). Measurements from IFS, SAM IFS, and IRDIS suggest an M6 spectral type for HD142527B, with an uncertainty of one spectral subtype, compatible with an object of M = 0.11 +/- 0.06 M-circle dot and R = 0.15 +/- 0.07 R-circle dot. The determination of the mass remains a challenge using contemporary evolutionary models, as they do not account for the energy input due to accretion from infalling material. We consider that the spectral type of the secondary may also be earlier than the type we derived from IFS spectra. From dynamical considerations, we further constrain the mass to 0.26(-0.14)(+0.16) , which is consistent with both our spectroscopic analysis and the values reported in the literature. Following previous methods, the lower and upper dynamical mass values correspond to a spectral type between M2.5 and M5.5 for the companion. By fitting the astrometric points, we find the following orbital parameters: a period of P = 35 137 yr; an inclination of i = 121 130 degrees, a value of Omega = 124 135 degrees for the longitude of node, and an 68% confidence interval of similar to 18-57 au for the separation at periapsis. Eccentricity and time at periapsis passage exhibit two groups of values: similar to 0.2-0.45 and similar to 0.45-0.7 for e, and similar to 2015-2020 and similar to 2020-2022 for T-0. While these orbital parameters might at first suggest that HD142527B is not the companion responsible for the outer disk truncation, a previous hydrodynamical analysis of this system showed that they are compatible with a companion that is able to produce the large cavity and other observed features.
16.	Gratton, R., et al. (författare) Investigating three Sirius-like systems with SPHERE 2021 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 646 Tidskriftsartikel (refereegranskat)abstract Context. Sirius-like systems are relatively wide binaries with a separation from a few to hundreds of au; they are composed of a white dwarf (WD) and a companion of a spectral type earlier than M0. Here we consider main sequence (MS) companions, where the WD progenitor evolves in isolation, but its wind during the former asymptotic giant branch (AGB) phase pollutes the companion surface and transfers some angular momentum. They are rich laboratories to constrain stellar models and binary evolution.Aims. Within the SpHere INfrared survey for Exoplanet survey that uses the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument at the Very Large Telescope, our goal is to acquire high contrast multi-epoch observations of three Sirius-like systems, HD 2133, HD 114174, and CD-56 7708 and to combine this data with archive high resolution spectra of the primaries, TESS archive, and literature data.Methods. These WDs are easy targets for SPHERE and were used as spectrophotometric standards. We performed very accurate abundance analyses for the MS stars using methods considered for solar analogs. Whenever possible, WD parameters and orbits were obtained using Monte Carlo Markov chain methods.Results. We found brighter J and K magnitudes for HD 114174B than obtained previously and extended the photometry down to 0.95 μm. Our new data indicate a higher temperature and then shorter cooling age (5.57 ± 0.02 Gyr) and larger mass (0.75 ± 0.03 M⊙) for this WD than previously assumed. Together with the oldest age for the MS star connected to the use of the Gaia DR2 distance, this solved the discrepancy previously found with the age of the MS star. The two other WDs are less massive, indicating progenitors of ∼1.3 M⊙ and 1.5 − 1.8 M⊙ for HD 2133B and CD-56 7708B, respectively. In spite of the rather long periods, we were able to derive useful constraints on the orbit for HD 114174 and CD-56 7708. They are both seen close to edge-on, which is in agreement with the inclination of the MS stars that are obtained coupling the rotational periods, stellar radii, and the projected rotational velocity from spectroscopy. The composition of the MS stars agrees fairly well with expectations from pollution by the AGB progenitors of the WDs: HD 2133A has a small enrichment of n-capture elements, which is as expected for pollution by an AGB star with an initial mass < 1.5 M⊙; CD-56 7708A is a previously unrecognized mild Ba-star, which is also expected due to pollution by an AGB star with an initial mass in the range of 1.5 − 3.0 M⊙; and HD 114174 has a very moderate excess of n-capture elements, which is in agreement with the expectation for a massive AGB star to have an initial mass > 3.0 M⊙.Conclusions. On the other hand, none of these stars show the excesses of C that are expected to go along with those of n-capture elements. This might be related to the fact that these stars are at the edges of the mass range where we expect nucleosynthesis related to thermal pulses. More work, both theoretical and observational, is required to better understand this issue.
17.	Lazzoni, C., et al. (författare) The search for disks or planetary objects around directly imaged companions : a candidate around DH Tauri B 2020 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 641 Tidskriftsartikel (refereegranskat)abstract Context. In recent decades, thousands of substellar companions have been discovered with both indirect and direct methods of detection. While the majority of the sample is populated by objects discovered using radial velocity and transit techniques, an increasing number have been directly imaged. These planets and brown dwarfs are extraordinary sources of information that help in rounding out our understanding of planetary systems.Aims. In this paper, we focus our attention on substellar companions detected with the latter technique, with the primary goal of investigating their close surroundings and looking for additional companions and satellites, as well as disks and rings. Any such discovery would shed light on many unresolved questions, particularly with regard to their possible formation mechanisms.Methods. To reveal bound features of directly imaged companions, whether for point-like or extended sources, we need to suppress the contribution from the source itself. Therefore, we developed a method based on the negative fake companion technique that first estimates the position in the field of view (FoV) and the flux of the imaged companion with high precision, then subtracts a rescaled model point spread function (PSF) from the imaged companion, using either an image of the central star or another PSF in the FoV. Next it performs techniques, such as angular differential imaging, to further remove quasi-static patterns of the star (i.e., speckle contaminants) that affect the residuals of close-in companions.Results. After testing our tools on simulated companions and disks and on systems that were chosen ad hoc, we applied the method to the sample of substellar objects observed with SPHERE during the SHINE GTO survey. Among the 27 planets and brown dwarfs we analyzed, most objects did not show remarkable features, which was as expected, with the possible exception of a point source close to DH Tau B. This candidate companion was detected in four different SPHERE observations, with an estimated mass of ~1MJup, and a mass ratio with respect to the brown dwarf of 1∕10. This binary system, if confirmed, would be the first of its kind, opening up interesting questions for the formation mechanism, evolution, and frequency of such pairs. In order to address the latter, the residuals and contrasts reached for 25 companions in the sample of substellar objects observed with SPHERE were derived. If the DH Tau Bb companion is real, the binary fraction obtained is ~7%, which is in good agreement with the results obtained for field brown dwarfs.Conclusions. While there may currently be many limitations affecting the exploration of bound features to directly imaged exoplanets and brown dwarfs, next-generation instruments from the ground and space (i.e., JWST, ELT, and LUVOIR) will be able to image fainter objects and, thus, drive the application of this technique in upcoming searches for exo-moons and circumplanetary disks.
18.	Maire, A. -L., et al. (författare) VLT/SPHERE astrometric confirmation and orbital analysis of the brown dwarf companion HR 2562 B 2018 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 615 Tidskriftsartikel (refereegranskat)abstract Context. A low-mass brown dwarf has recently been imaged around HR 2562 (HD 50571), a star hosting a debris disk resolved in the far infrared. Interestingly, the companion location is compatible with an orbit coplanar with the disk and interior to the debris belt. This feature makes the system a valuable laboratory to analyze the formation of substellar companions in a circumstellar disk and potential disk-companion dynamical interactions. Aims. We aim to further characterize the orbital motion of HR 2562 B and its interactions with the host star debris disk. Methods. We performed a monitoring of the system over similar to 10 months in 2016 and 2017 with the VLT/SPHERE exoplanet imager. Results. We confirm that the companion is comoving with the star and detect for the first time an orbital motion at high significance, with a current orbital motion projected in the plane of the sky of 25 mas (similar to 0.85 au) per year. No orbital curvature is seen in the measurements. An orbital fit of the SPHERE and literature astrometry of the companion without priors on the orbital plane clearly indicates that its orbit is (quasi-)coplanar with the disk. To further constrain the other orbital parameters, we used empirical laws for a companion chaotic zone validated by N-body simulations to test the orbital solutions that are compatible with the estimated disk cavity size. Non-zero eccentricities (>0.15) are allowed for orbital periods shorter than 100 yr, while only moderate eccentricities up to similar to 0.3 for orbital periods longer than 200 yr are compatible with the disk observations. A comparison of synthetic Herschel images to the real data does not allow us to constrain the upper eccentricity of the companion.
19.	Mueller, A., et al. (författare) Orbital and atmospheric characterization of the planet within the gap of the PDS70 transition disk 2018 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 617 Tidskriftsartikel (refereegranskat)abstract Context. The observation of planets in their formation stage is a crucial but very challenging step in understanding when, how, and where planets form. PDS 70 is a young pre-main sequence star surrounded by a transition disk, in the gap of which a planetary-mass companion has recently been discovered. This discovery represents the first robust direct detection of such a young planet, possibly still at the stage of formation.Aims. We aim to characterize the orbital and atmospheric properties of PDS 70 b, which was first identified on May 2015 in the course of the SHINE survey with SPHERE, the extreme adaptive-optics instrument at the VLT.Methods. We obtained new deep SPHERE/IRDIS imaging and SPHERE/IFS spectroscopic observations of PDS 70 b. The astrometric baseline now covers 6 yr, which allowed us to perform an orbital analysis. For the first time, we present spectrophotometry of the young planet which covers almost the entire near-infrared range (0.96-3.8 mu m). We use different atmospheric models covering a large parameter space in temperature, log g, chemical composition, and cloud properties to characterize the properties of the atmosphere of PDS 70 b.Results. PDS 70 b is most likely orbiting the star on a circular and disk coplanar orbit at similar to 22 au inside the gap of the disk. We find a range of models that can describe the spectrophotometric data reasonably well in the temperature range 1000-1600 K and log g no larger than 3.5 dex. The planet radius covers a relatively large range between 1.4 and 3.7 R-J with the larger radii being higher than expected from planet evolution models for the age of the planet of 5.4 Myr. Conclusions. This study provides a comprehensive data set on the orbital motion of PDS 70 b, indicating a circular orbit and a motion coplanar with the disk. The first detailed spectral energy distribution of PDS 70 b indicates a temperature typical of young giant planets. The detailed atmospheric analysis indicates that a circumplanetary disk may contribute to the total planetflux.
20.	Ginski, C., et al. (författare) An extended scattered light disk around AT Pyx. Possible planet formation in a cometary globule 2022 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 662 Tidskriftsartikel (refereegranskat)abstract Aims. To understand how the multitude of planetary systems that have been discovered come to be, we need to study systems at different evolutionary stages, with different central stars but also in different environments. The most challenging environment for planet formation may be the harsh UV radiation field of nearby massive stars which quickly erodes disks by external photo-evaporation. We observed the AT Pyx system, located in the head of a cometary globule in the Gum Nebula, to search for signs of ongoing planet formation.Methods. We used the extreme adaptive optics imager VLT/SPHERE in Dual Beam Polarization Imaging Mode in H-band as well as in IRDIFS Extended mode (K12-band imaging and Y-H integral field spectroscopy) to observe AT Pyx in polarized light and total intensity. Additionally, we employed VLT/NACO to observe the system in the L-band.Results. We resolve the disk around AT Pyx for the first time in scattered light across multiple wavelengths in polarized light and total intensity. We find an extended (≥126 au) disk, with an intermediate inclination of between 35° and 42°. The disk shows a complex substructure and we identify two or possibly three spiral-like features. Depending on the precise geometry of the disk (which we cannot unambiguously infer from our data), the disk may be eccentric with an eccentricity of ~0.16 or partially self-shadowed. The spiral features and possible eccentricity are both consistent with signatures of an embedded gas giant planet with a mass of ~1 MJup. Our own observations can rule out brown dwarf companions embedded in the resolved disk, but are nevertheless not sensitive enough to confirm or rule out the presence of a gas giant.Conclusions. AT Pyx is the first disk to be spatially resolved in a cometary globule in the Gum Nebula. By comparison with disks in the Orion Nebula Cluster we note that the extension of the disk may be exceptional for this environment if the external UV radiation field is indeed comparable to other cometary globules in the region. The signposts of ongoing planet formation are intriguing and need to be followed up with either higher sensitivity or at different wavelengths.
21.	Mesa, D., et al. (författare) VLT/SPHERE exploration of the young multiplanetary system PDS70 2019 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 632 Tidskriftsartikel (refereegranskat)abstract Context. PDS 70 is a young (5.4 Myr), nearby (similar to 113 pc) star hosting a known transition disk with a large gap. Recent observations with SPHERE and NACO in the near-infrared (NIR) allowed us to detect a planetary mass companion, PDS 70 b, within the disk cavity. Moreover, observations in H-alpha with MagAO and MUSE revealed emission associated to PDS 70 b and to another new companion candidate, PDS 70 c, at a larger separation from the star. PDS 70 is the only multiple planetary system at its formation stage detected so far through direct imaging.Aims. Our aim is to confirm the discovery of the second planet PDS 70 c using SPHERE at VLT, to further characterize its physical properties, and search for additional point sources in this young planetary system.Methods. We re-analyzed archival SPHERE NIR observations and obtained new data in Y, J, H and K spectral bands for a total of four different epochs. The data were reduced using the data reduction and handling pipeline and the SPHERE data center. We then applied custom routines (e.g., ANDROMEDA and PACO) to subtract the starlight.Results. We re-detect both PDS 70 b and c and confirm that PDS 70 c is gravitationally bound to the star. We estimate this second planet to be less massive than 5 M-Jup and with a T-eff around 900 K. Also, it has a low gravity with log g between 3.0 and 3.5 dex. In addition, a third object has been identified at short separation (similar to 0.12 '') from the star and gravitationally bound to the star. Its spectrum is however very blue, meaning that we are probably seeing stellar light reflected by dust and our analysis seems to demonstrate that it is a feature of the inner disk. We cannot however completely exclude the possibility that it is a planetary mass object enshrouded by a dust envelope. In this latter case, its mass should be of the order of a few tens of M-circle plus. Moreover, we propose a possible structure for the planetary system based on our data, and find that this structure cannot be stable on a long timescale.
22.	Mesa, D., et al. (författare) Limits on the presence of planets in systems with debris discs : HD92945 and HD107146 2021 Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 503:1, s. 1276-1289 Tidskriftsartikel (refereegranskat)abstract Recent observations of resolved cold debris discs at tens of au have revealed that gaps could be a common feature in these Kuiper-belt analogues. Such gaps could be evidence for the presence of planets within the gaps or closer in near the edges of the disc. We present SPHERE observations of HD 92945 and HD 107146, two systems with detected gaps. We constrained the mass of possible companions responsible for the gap to 1–2 MJup for planets located inside the gap and to less than 5 MJup for separations down to 20 au from the host star. These limits allow us to exclude some of the possible configurations of the planetary systems proposed to explain the shape of the discs around these two stars. In order to put tighter limits on the mass at very short separations from the star, where direct-imaging data are less effective, we also combined our data with astrometric measurements from Hipparcos and Gaia and radial-velocity measurements. We were able to limit the separation and the mass of the companion potentially responsible for the proper-motion anomaly of HD 107146 to values of 2–7 au and 2–5 MJup, respectively.
23.	Muro-Arena, G. A., et al. (författare) Shadowing and multiple rings in the protoplanetary disk of HD 139614 2020 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 635 Tidskriftsartikel (refereegranskat)abstract Context. Shadows in scattered light images of protoplanetary disks are a common feature and support the presence of warps or misalignments between disk regions. These warps are possibly caused by an inclined (sub-)stellar companion embedded in the disk. Aims. We aim to study the morphology of the protoplanetary disk around the Herbig Ae star HD 139614 based on the first scattered light observations of this disk, which we model with the radiative transfer code MCMax3D. Methods. We obtained J- and H-band observations that show strong azimuthal asymmetries in polarized scattered light with VLT/SPHERE. In the outer disk, beyond similar to 30 au, a broad shadow spans a range of similar to 240 deg in position angle, in the east. A bright ring at similar to 16 au also shows an azimuthally asymmetric brightness, with the faintest side roughly coincidental with the brightest region of the outer disk. Additionally, two arcs are detected at similar to 34 and similar to 50 au. We created a simple four-zone approximation to a warped disk model of HD 139614 in order to qualitatively reproduce these features. The location and misalignment of the disk components were constrained from the shape and location of the shadows they cast. Results. We find that the shadow on the outer disk covers a range of position angles too wide to be explained by a single inner misaligned component. Our model requires a minimum of two separate misaligned zones - or a continuously warped region - to cast this broad shadow on the outer disk. A small misalignment of similar to 4 degrees between adjacent components can reproduce most of the observed shadow features. Conclusions. Multiple misaligned disk zones, potentially mimicking a warp, can explain the observed broad shadows in the HD 139614 disk. A planetary mass companion in the disk, located on an inclined orbit, could be responsible for such a feature and for the dust-depleted gap responsible for a dip in the SED.
24.	Singh, G., et al. (författare) Revealing asymmetrical dust distribution in the inner regions of HD 141569 2021 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 653 Tidskriftsartikel (refereegranskat)abstract Context. The combination of high-contrast imaging with spectroscopy and polarimetry offers a pathway to studying the grain distribution and properties of debris disks in exquisite detail. Here, we focus on the case of a gas-rich debris disk around HD 141569A, which features a multiple-ring morphology first identified with SPHERE in the near-infrared.Aims. We obtained polarimetric differential imaging with SPHERE in the H-band to compare the scattering properties of the innermost ring at 44 au with former observations in total intensity with the same instrument. In polarimetric imaging, we observed that the intensity of the ring peaks in the south-east, mostly in the forward direction, whereas in total intensity imaging, the ring is detected only at the south. This noticeable characteristic suggests a non-uniform dust density in the ring. With these two sets of images, we aim to study the distribution of the dust to solve for the actual dust distribution.Methods. We implemented a density function varying azimuthally along the ring and generated synthetic images both in polarimetry and in total intensity, which are then compared to the actual data. The search for the best-fit model was performed both with a grid-based and an MCMC approach. Using the outcome of this modelization, we further measured the polarized scattering phase function for the observed scattering angle between 33 degrees and 147 degrees as well as the spectral reflectance of the southern part of the ring between 0.98 and 2.1 mu m. We tentatively derived the grain properties by comparing these quantities with MCFOST models and assuming Mie scattering.Results. We find that the dust density peaks in the south-west at an azimuthal angle of 220 degrees similar to 238 degrees with a rather broad width of 61 degrees similar to 127 degrees. The difference in the intensity distributions observed in polarimetry and total intensity is the result of this particular morphology. Although there are still uncertainties that remain in the determination of the anisotropic scattering factor, the implementation of an azimuthal density variation to fit the data proved to be robust. Upon elaborating on the origin of this dust density distribution, we conclude that it could be the result of a massive collision when we account for the effect of the high gas mass that is present in the system on the dynamics of grains. In terms of grain composition, our preliminary interpretation indicates a mixture of porous sub-micron sized astro-silicate and carbonaceous grains.Conclusions. The SPHERE observations have allowed, for the first time, for meaningful constraints to be placed on the dust distribution beyond the standard picture of a uniform ring-like debris disk. However, future studies with a multiwavelength approach and additional detailed modeling would be required to better characterize the grain properties in the HD 141569 system.
25.	Keppler, M., et al. (författare) Gap, shadows, spirals, and streamers : SPHERE observations of binary-disk interactions in GG Tauri A 2020 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 639 Tidskriftsartikel (refereegranskat)abstract Context. A large portion of stars is found to be part of binary or higher-order multiple systems. The ubiquity of planets found around single stars raises the question of whether and how planets in binary systems form. Protoplanetary disks are the birthplaces of planets, and characterizing them is crucial in order to understand the planet formation process.Aims. Our goal is to characterize the morphology of the GG Tau A disk, one of the largest and most massive circumbinary disks. We also aim to trace evidence for binary-disk interactions.Methods. We obtained observations in polarized scattered light of GG Tau A using the SPHERE/IRDIS instrument in the H-band filter. We analyzed the observed disk morphology and substructures. We ran 2D hydrodynamical models to simulate the evolution of the circumbinary ring over the lifetime of the disk.Results. The disk and also the cavity and the inner region are highly structured, with several shadowed regions, spiral structures, and streamer-like filaments. Some of these are detected here for the first time. The streamer-like filaments appear to connect the outer ring with the northern arc. Their azimuthal spacing suggests that they may be generated through periodic perturbations by the binary, which tear off material from the inner edge of the outer disk once during each orbit. By comparing observations to hydrodynamical simulations, we find that the main features, in particular, the gap size, but also the spiral and streamer filaments, can be qualitatively explained by the gravitational interactions of a binary with a semimajor axis of similar to 35 au on an orbit coplanar with the circumbinary ring.
26.	Pohl, A., et al. (författare) The Circumstellar Disk HD 169142 : Gas, Dust, and Planets Acting in Concert? 2017 Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 850:1 Tidskriftsartikel (refereegranskat)abstract HD 169142 is an excellent target for investigating signs of planet-disk interaction due to previous evidence of gap structures. We perform J-band (similar to 1.2 mu m) polarized intensity imaging of HD 169142 with VLT/SPHERE. We observe polarized scattered light down to 0 ''.16 (similar to 19 au) and find an inner gap with a significantly reduced scattered-light flux. We confirm the previously detected double-ring structure peaking at 0 ''.18 (similar to 21 au) and 0 ''.56 (similar to 66 au) and marginally detect a faint third gap at 0 ''.70-0 ''.73 (similar to 82-85 au). We explore dust evolution models in a disk perturbed by two giant planets, as well as models with a parameterized dust size distribution. The dust evolution model is able to reproduce the ring locations and gap widths in polarized intensity but fails to reproduce their depths. However, it gives a good match with the ALMA dust continuum image at 1.3 mm. Models with a parameterized dust size distribution better reproduce the gap depth in scattered light, suggesting that dust filtration at the outer edges of the gaps is less effective. The pileup of millimeter grains in a dust trap and the continuous distribution of small grains throughout the gap likely require more efficient dust fragmentation and dust diffusion in the dust trap. Alternatively, turbulence or charging effects might lead to a reservoir of small grains at the surface layer that is not affected by the dust growth and fragmentation cycle dominating the dense disk midplane. The exploration of models shows that extracting planet properties such as mass from observed gap profiles is highly degenerate.
27.	Wright, Graham D., et al. (författare) Recognising the importance and impact of Imaging Scientists: Global guidelines for establishing career paths within core facilities 2024 Ingår i: JOURNAL OF MICROSCOPY. - 0022-2720 .- 1365-2818. ; 294:3, s. 397-410 Tidskriftsartikel (refereegranskat)abstract In the dynamic landscape of scientific research, imaging core facilities are vital hubs propelling collaboration and innovation at the technology development and dissemination frontier. Here, we present a collaborative effort led by Global BioImaging (GBI), introducing international recommendations geared towards elevating the careers of Imaging Scientists in core facilities. Despite the critical role of Imaging Scientists in modern research ecosystems, challenges persist in recognising their value, aligning performance metrics and providing avenues for career progression and job security. The challenges encompass a mismatch between classic academic career paths and service-oriented roles, resulting in a lack of understanding regarding the value and impact of Imaging Scientists and core facilities and how to evaluate them properly. They further include challenges around sustainability, dedicated training opportunities and the recruitment and retention of talent. Structured across these interrelated sections, the recommendations within this publication aim to propose globally applicable solutions to navigate these challenges. These recommendations apply equally to colleagues working in other core facilities and research institutions through which access to technologies is facilitated and supported. This publication emphasises the pivotal role of Imaging Scientists in advancing research programs and presents a blueprint for fostering their career progression within institutions all around the world. In the exciting world of scientific research, imaging core facilities are essential hubs where scientists use advanced technologies to conduct experiments and uncover fascinating discoveries. What makes these facilities remarkable is that multiple scientists can access and utilise a variety of instruments for a wide range of multidisciplinary research projects, fostering collaboration and innovation. At the forefront of this scientific adventure are Imaging Scientists, experts who play a crucial role in planning experiments, preparing materials, adapting and acquiring technologies, collecting data, training and supporting researchers, analysing images and forming conclusions. Despite their pivotal contributions, there are challenges in recognising the importance of Imaging Scientists and ensuring they have ample opportunities to advance in their careers. These challenges include a mismatch between the typical academic career path and the unique roles and responsibilities of Imaging Scientists, a lack of widespread understanding of their value plus financial constraints, insufficient training opportunities, and difficulties in attracting and retaining talented individuals. To address these issues, Global BioImaging (GBI; www.globalbioimaging.org) has brought together Imaging Scientists from around the world to develop a generally applicable set of recommendations in three key areas: highlighting the significance and value of Imaging Scientists, making it easier to recruit and retain them, and supporting their ongoing learning and professional growth. A notable concept is to reimagine the traditional separation between academic roles and technical support roles. GBI envisions that these recommendations will not only benefit imaging facilities but also prove valuable for research institutions housing diverse technologies organised into core facilities. Recognising the diverse nature of research performing institutions globally, the GBI community sees this guide as a starting point that will initiate dialogue and instigate change, which should be periodically updated as the needs of Imaging Scientists change. This initial version lays a solid foundation for future enhancements, contributing to the acknowledgement and support of the invaluable work done by Imaging Scientists on a global scale.
28.	Muro-Arena, G. A., et al. (författare) Spirals inside the millimeter cavity of transition disk SR 21 2020 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 636 Tidskriftsartikel (refereegranskat)abstract Context. Hydrodynamical simulations of planet-disk interactions suggest that planets may be responsible for a number of the substructures frequently observed in disks in both scattered light and dust thermal emission. Despite the ubiquity of these features, direct evidence of planets embedded in disks and of the specific interaction features like spiral arms within planetary gaps are still rare.Aims. In this study we discuss recent observational results in the context of hydrodynamical simulations in order to infer the properties of a putative embedded planet in the cavity of a transition disk.Methods. We imaged the transition disk SR 21 in H-band in scattered light with SPHERE/IRDIS and in thermal dust emission with ALMA band 3 (3 mm) observations at a spatial resolution of 0.1 ''. We combine these datasets with existing Band 9 (430 mu m) and Band 7 (870 mu m) ALMA continuum data.Results. The Band 3 continuum data reveals a large cavity and a bright ring peaking at 53 au strongly suggestive of dust trapping. The ring shows a pronounced azimuthal asymmetry, with a bright region in the northwest that we interpret as a dust overdensity. A similarly asymmetric ring is revealed at the same location in polarized scattered light, in addition to a set of bright spirals inside the millimeter cavity and a fainter spiral bridging the gap to the outer ring. These features are consistent with a number of previous hydrodynamical models of planet-disk interactions, and suggest the presence of a similar to 1 M-Jup planet at 44 au and PA = 11 deg. This makes SR21 the first disk showing spiral arms inside the millimeter cavity, and the first disk for which the location of a putative planet can be precisely inferred.Conclusions. The main features of SR 21 in both scattered light and thermal emission are consistent with hydrodynamical predictions of planet-disk interactions. With the location of a possible planet being well constrained by observations, it is an ideal candidate for follow-up observations to search for direct evidence of a planetary companion still embedded in its disk.
29.	Asensio-Torres, R., et al. (författare) Perturbers : SPHERE detection limits to planetary-mass companions in protoplanetary disks 2021 Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 652 Tidskriftsartikel (refereegranskat)abstract The detection of a wide range of substructures such as rings, cavities, and spirals has become a common outcome of high spatial resolution imaging of protoplanetary disks, both in the near-infrared scattered light and in the thermal millimetre continuum emission. The most frequent interpretation of their origin is the presence of planetary-mass companions perturbing the gas and dust distribution in the disk (perturbers), but so far the only bona fide detection has been the two giant planets carving the disk around PDS 70. Here, we present a sample of 15 protoplanetary disks showing substructures in SPHERE scattered-light images and a homogeneous derivation of planet detection limits in these systems. To obtain mass limits we rely on different post-formation luminosity models based on distinct formation conditions, which are critical in the first million years of evolution. We also estimate the mass of these perturbers through a Hill radius prescription and a comparison to ALMA data. Assuming that one single planet carves each substructure in scattered light, we find that more massive perturbers are needed to create gaps within cavities than rings, and that we might be close to a detection in the cavities of RX J1604.3-2130A, RX J1615.3-3255, Sz Cha, HD 135344B, and HD 34282. We reach typical mass limits in these cavities of 3–10 MJup. For planets in the gaps between rings, we find that the detection limits of SPHERE high-contrast imaging are about an order of magnitude away in mass, and that the gaps of PDS 66 and HD 97048 seem to be the most promising structures for planet searches. The proposed presence of massive planets causing spiral features in HD 135344B and HD 36112 are also within SPHERE’s reach assuming hot-start models. These results suggest that the current detection limits are able to detect hot-start planets in cavities, under the assumption that they are formed by a single perturber located at the centre of the cavity. More realistic planet mass constraints would help to clarify whether this is actually the case, which might indicate that perturbers are not the only way of creating substructures.
30.	Quinten, E, et al. (författare) Autonomous B-cell receptor signaling and genetic aberrations in chronic lymphocytic leukemia-phenotype monoclonal B lymphocytosis in siblings of patients with chronic lymphocytic leukemia 2024 Ingår i: Haematologica. - 1592-8721. ; 109:3, s. 824-834 Tidskriftsartikel (refereegranskat)
31.	Bjarnadottir, M, et al. (författare) Intracellular accumulation of the amyloidogenic L68Q variant of cystatin C in NIH/3T3 cells 1998 Ingår i: Molecular Pathology. - 1366-8714. ; 51:6, s. 317-326 Tidskriftsartikel (refereegranskat)abstract AIM: To study the cellular transport of L68Q cystatin C, the cystatin variant causing amyloidosis and brain haemorrhage in patients suffering from hereditary cystatin C amyloid angiopathy (HCCAA). METHODS: Expression vectors for wild-type and L68Q cystatin C were constructed and used to transfect mouse NIH/3T3 cells. Stable cell clones were isolated after cotransfection with pSV2neo. Clones expressing human wild-type and L68Q cystatin C were compared with respect to secreted cystatin C by enzyme linked immunosorbent assay (ELISA), and for intracellular cystatin C by western blotting and immunofluorescence cytochemistry. Colocalisation studies in cells were performed by double staining with antibodies against human cystatin C and marker proteins for lysosomes, the Golgi apparatus, or the endoplasmic reticulum, and evaluated by confocal microscopy. RESULTS: Concentrations of human cystatin C secreted from transfected NIH/3T3 cells were similar to those secreted from human cells in culture. In general, clones expressing the gene encoding L68Q cystatin C secreted slightly lower amounts of the protein than clones expressing wild-type human cystatin C. Both immunofluorescence cytochemistry and western blotting experiments showed an increased accumulation of cystatin C in cells expressing the gene encoding L68Q cystatin C compared with cells expressing the gene for the wild-type protein. The intracellularly accumulating L68Q cystatin C was insoluble and located mainly in the endoplasmic reticulum. CONCLUSIONS: The cellular transport of human cystatin C is impeded by the pathogenic amino acid substitution Leu68-- >Gln. The resulting intracellular accumulation and increased localised concentration of L68Q cystatin C might be an important event in the molecular pathophysiology of amyloid formation and brain haemorrhage in patients with HCCAA.
32.	Bjarnadottir, M, et al. (författare) Intracellular accumulation of the amyloidogenic L68Q variant of human cystatin C in NIH/3T3 cells 1998 Ingår i: Molecular Pathology. - : BMJ. - 1366-8714. ; 51, s. 317-326 Tidskriftsartikel (refereegranskat)abstract AIM: To study the cellular transport of L68Q cystatin C, the cystatin variant causing amyloidosis and brain haemorrhage in patients suffering from hereditary cystatin C amyloid angiopathy (HCCAA).METHODS: Expression vectors for wild-type and L68Q cystatin C were constructed and used to transfect mouse NIH/3T3 cells. Stable cell clones were isolated after cotransfection with pSV2neo. Clones expressing human wild-type and L68Q cystatin C were compared with respect to secreted cystatin C by enzyme linked immunosorbent assay (ELISA), and for intracellular cystatin C by western blotting and immunofluorescence cytochemistry. Colocalisation studies in cells were performed by double staining with antibodies against human cystatin C and marker proteins for lysosomes, the Golgi apparatus, or the endoplasmic reticulum, and evaluated by confocal microscopy.RESULTS: Concentrations of human cystatin C secreted from transfected NIH/3T3 cells were similar to those secreted from human cells in culture. In general, clones expressing the gene encoding L68Q cystatin C secreted slightly lower amounts of the protein than clones expressing wild-type human cystatin C. Both immunofluorescence cytochemistry and western blotting experiments showed an increased accumulation of cystatin C in cells expressing the gene encoding L68Q cystatin C compared with cells expressing the gene for the wild-type protein. The intracellularly accumulating L68Q cystatin C was insoluble and located mainly in the endoplasmic reticulum.CONCLUSIONS: The cellular transport of human cystatin C is impeded by the pathogenic amino acid substitution Leu68-->Gln. The resulting intracellular accumulation and increased localised concentration of L68Q cystatin C might be an important event in the molecular pathophysiology of amyloid formation and brain haemorrhage in patients with HCCAA.
33.	Ducani, C, et al. (författare) Interplay of Three G-Quadruplex Units in the KIT Promoter 2019 Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 141:26, s. 10205-10213 Tidskriftsartikel (refereegranskat)
34.	Gibbons, R, et al. (författare) Mutations in transcriptional regulator ATRX establish the functional significance of a PHD-like domain. 1997 Ingår i: Nature Genet. ; 17, s. 146- Tidskriftsartikel (refereegranskat)
35.	Heffeter, P., et al. (författare) Ribonucleotide Reductase as One Important Target of [Tris(1,10- phenanthroline)lanthanum(III)] Trithiocyanate (KP772) 2009 Ingår i: Current Cancer Drug Targets. - : Bentham Science Publishers Ltd.. - 1568-0096 .- 1873-5576. ; 9:5, s. 595-607 Tidskriftsartikel (refereegranskat)abstract KP772 is a new lanthanum complex containing three 1,10-phenathroline molecules. Recently, we have demonstrated that the promising in vitro and in vivo anticancer properties of KP772 are based on p53-independent G(0)G(1) arrest and apoptosis induction. A National Cancer Institute (NCI) screen revealed significant correlation of KP772 activity with that of the ribonucleotide reductase (RR) inhibitor hydroxyurea (HU). Consequently, this study aimed to investigate whether KP772 targets DNA synthesis in tumor cells by RR inhibition. Indeed, KP772 treatment led to significant reduction of cytidine incorporation paralleled by a decrease of deoxynucleoside triphosphate (dNTP) pools. This strongly indicates disruption of RR activity. Moreover, KP772 protected against oxidative stress, suggesting that this drug might interfere with RR by interaction with the tyrosyl radical in subunit R2. Additionally, several observations (e.g. increase of transferrin receptor expression and protective effect of iron preloading) indicate that KP772 interferes with cellular iron homeostasis. Accordingly, co-incubation of Fe(II) with KP772 led to generation of a coloured iron complex (Fe-KP772) in cell free systems. In electron paramagnetic resonance (EPR) measurements of mouse R2 subunits, KP772 disrupted the tyrosyl radical while Fe-KP772 had no significant effects. Moreover, coincubation of KP772 with iron-loaded R2 led to formation of Fe-KP772 suggesting chelation of RR-bound Fe(II). Summarizing, our data prove that KP772 inhibits RR by targeting the iron centre of the R2 subunit. As also Fe-KP772 as well as free lanthanum exert significant -though less pronounced- cytotoxic/static activities, additional mechanisms are likely to synergise with RR inhibition in the promising anticancer activity of KP772.
36.	Stollenwerk, Maria M, 1959-, et al. (författare) Albumin-based nanoparticles as magnetic resonance contrast agents : I. Concept, first syntheses and characterisation 2010 Ingår i: Histochemistry and Cell Biology. - : Springer. - 0948-6143 .- 1432-119X. ; 133:4, s. 375-404 Tidskriftsartikel (refereegranskat)abstract Abstract To develop a platform for molecular magnetic resonance imaging, we prepared gadolinium-bearing albumin-polylactic acid nanoparticles in the size range 20–40 nm diameter. Iterative cycles of design and testing upscaled the synthesis procedures to gram amounts for physicochemical characterisation and for pharmacokinetic testing. Morphological analyses showed that the nanoparticles were spheroidal with rough surfaces. Particle sizes were measured by direct transmission electron microscopical measurements from negatively contrasted preparations, and by use of photon correlation spectroscopy; the two methods each documented nanoparticle sizes less than 100 nm and generally 10–40 nm diameter, though with significant intrabatch and interbatch variability. The particles’ charge sufficed to hold them in suspension. HSA retained its tertiary structure in the particles. The nanoparticles were stable against turbulent flow conditions and against heat, though not against detergents. MRI imaging of liquid columns was possible at nanoparticle concentrations below 10 mg/ml. The particles were non-cytotoxic, non-thrombogenic and non-immunogenic in a range of assay systems developed for toxicity testing of nanoparticles. They were micellar prior to lyophilisation, but loosely structured aggregated masses after lyophilisation and subsequent resuspension. These nanoparticles provide a platform for further development, based on non-toxic materials of low immunogenicity already in clinical use,not expensive, and synthesized using methods which can be upscaled for industrial production.

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