| 1. |
- Lacour, S., et al.
(författare)
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The mass of β Pictoris c from β Pictoris b orbital motion
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 654
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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.
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| 2. |
- Lagrange, A. M., et al.
(författare)
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Unveiling the beta Pictoris system, coupling high contrast imaging, interferometric, and radial velocity data
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 642
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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.
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| 3. |
- Marconi, Alessandro, et al.
(författare)
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ELT-HIRES, the high resolution spectrograph for the ELT : Phase A study and path to construction
- 2020
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy VIII. - : SPIE - International Society for Optical Engineering. - 9781510636828 - 9781510636811
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Konferensbidrag (refereegranskat)abstract
- HIRES is the high-resolution spectrograph of the European Extremely Large Telescope at optical and near-infrared wavelengths. It consists of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 µm (goal 0.35-2.4 µm) at a spectral resolution of 100,000. The fibre-feeding allows HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU in the NIR. Therefore, it will be able to operate both in seeing- and diffraction-limited modes. Its modularity will ensure that HIRES can be placed entirely on the Nasmyth platform, if enough mass and volume is available, or part on the Nasmyth and part in the Coud`e room. ELT-HIRES has a wide range of science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars (PopIII), tests on the stability of Nature’s fundamental couplings, and the direct detection of the cosmic acceleration. The HIRES consortium is composed of more than 30 institutes from 14 countries, forming a team of more than 200 scientists and engineers.
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| 4. |
- Kluska, J., et al.
(författare)
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VLTI images of circumbinary disks around evolved stars
- 2020
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 11446
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Konferensbidrag (refereegranskat)abstract
- The new generation of VLTI instruments (GRAVITY, MATISSE) aims to produce routinely interferometric images to uncover the morphological complexity of different objects at high angular resolution. Image reconstruction is, however, not a fully automated process. Here we focus on a specific science case, namely the complex circumbinary environments of a subset of evolved binaries, for which interferometric imaging provides the spatial resolution required to resolve the immediate circumbinary environment. Indeed, many binaries where the main star is in the post-asymptotic giant branch (post-AGB) phase are surrounded by circumbinary disks. Those disks were first inferred from the infrared excess produced by dust. Snapshot interferometric observations in the infrared confirmed disk-like morphology and revealed high spatial complexity of the emission that the use of geometrical models could not recover without being strongly biased. Arguably, the most convincing proof of the disk-like shape of the circumbinary environment came from the first interferometric image of such a system (IRAS08544-4431) using the PIONIER instrument at the VLTI. This image was obtained using the SPARCO image reconstruction approach that enables to subtract a model of a component of the image and reconstruct an image of its environment only. In the case of IRAS08544-4431, the model involved a binary and the image of the remaining signal revealed several unexpected features. Then, a second image revealed a different but also complex circumstellar morphology around HD101584 that was well studied by ALMA. To exploit the VLTI imaging capability to understand these targets, we started a large programme at the VLTI to image post-AGB binary systems using both PIONIER and GRAVITY instruments.
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| 5. |
- Chiavassa, A., et al.
(författare)
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Optical interferometry and Gaia measurement uncertainties reveal the physics of asymptotic giant branch stars
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 640
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Tidskriftsartikel (refereegranskat)abstract
- Context. Asymptotic giant branch (AGB) stars are cool luminous evolved stars that are well observable across the Galaxy and populating Gaia data. They have complex stellar surface dynamics, which amplifies the uncertainties on stellar parameters and distances.Aims. On the AGB star CL Lac, it has been shown that the convection-related variability accounts for a substantial part of the Gaia DR2 parallax error. We observed this star with the MIRC-X beam combiner installed at the CHARA interferometer to detect the presence of stellar surface inhomogeneities.Methods. We performed the reconstruction of aperture synthesis images from the interferometric observations at different wavelengths. Then, we used 3D radiative hydrodynamics (RHD) simulations of stellar convection with CO5BOLD and the post-processing radiative transfer code OPTIM3D to compute intensity maps in the spectral channels of MIRC-X observations. Then, we determined the stellar radius using the average 3D intensity profile and, finally, compared the 3D synthetic maps to the reconstructed ones focusing on matching the intensity contrast, the morphology of stellar surface structures, and the photocentre position at two different spectral channels, 1.52 and 1.70 mu m, simultaneously.Results. We measured the apparent diameter of CL Lac at two wavelengths (3.299 0.005 mas and 3.053 +/- 0.006 mas at 1.52 and 1.70 mu m, respectively) and recovered the radius (R = 307 +/- 41 and R = 284 +/- 38 R-circle dot) using a Gaia parallax. In addition to this, the reconstructed images are characterised by the presence of a brighter area that largely affects the position of the photocentre. The comparison with 3D simulation shows good agreement with the observations both in terms of contrast and surface structure morphology, meaning that our model is adequate for explaining the observed inhomogenities.Conclusions. This work confirms the presence of convection-related surface structures on an AGB star of Gaia DR2. Our result will help us to take a step forward in exploiting Gaia measurement uncertainties to extract the fundamental properties of AGB stars using appropriate RHD simulations.
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| 6. |
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| 7. |
- Hartman, E. A. R., et al.
(författare)
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Decisions on antibiotic prescribing for suspected urinary tract infections in frail older adults: a qualitative study in four European countries
- 2022
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Ingår i: Age and ageing. - : Oxford University Press (OUP). - 0002-0729 .- 1468-2834. ; 51:6
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Tidskriftsartikel (refereegranskat)abstract
- Background a suspected urinary tract infection (UTI) is the most common reason to prescribe antibiotics in a frail older patient. Frequently, antibiotics are prescribed unnecessarily. To increase appropriate antibiotic use for UTIs through antibiotic stewardship interventions, we need to thoroughly understand the factors that contribute to these prescribing decisions. Objectives (1) to obtain insight into factors contributing to antibiotic prescribing for suspected UTIs in frail older adults. (2) To develop an overarching model integrating these factors to guide the development of antibiotic stewardship interventions for UTIs in frail older adults. Methods we conducted an exploratory qualitative study with 61 semi-structured interviews in older adult care settings in Poland, the Netherlands, Norway and Sweden. We interviewed physicians, nursing staff, patients and informal caregivers. Results participants described a chain of decisions by patients, caregivers and/or nursing staff preceding the ultimate decision to prescribe antibiotics by the physician. We identified five themes of influence: (1) the clinical situation and its complexity within the frail older patient, (2) diagnostic factors, such as asymptomatic bacteriuria, (3) knowledge (gaps) and attitude, (4) communication: interprofessional, and with patients and relatives and (5) context and organisation of care, including factors such as availability of antibiotics (over the counter), antibiotic stewardship efforts and factors concerning out-of-hours care. Conclusions decision-making on suspected UTIs in frail older adults is a complex, multifactorial process. Due to the diverse international setting and stakeholder variety, we were able to provide a comprehensive overview of factors to guide the development of antibiotic stewardship interventions.
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| 8. |
- Hartman, Esther A R, et al.
(författare)
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Effect of a multifaceted antibiotic stewardship intervention to improve antibiotic prescribing for suspected urinary tract infections in frail older adults (ImpresU): pragmatic cluster randomised controlled trial in four European countries.
- 2023
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Ingår i: BMJ (Clinical research ed.). - : BMJ. - 0959-535X .- 1756-1833. ; 380
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate whether antibiotic prescribing for suspected urinary tract infections in frail older adults can be reduced through a multifaceted antibiotic stewardship intervention.Pragmatic, parallel, cluster randomised controlled trial, with a five month baseline period and a seven month follow-up period.38 clusters consisting of one or more general practices (n=43) and older adult care organisations (n=43) in Poland, the Netherlands, Norway, and Sweden, from September 2019 to June 2021.1041 frail older adults aged 70 or older (Poland 325, the Netherlands 233, Norway 276, Sweden 207), contributing 411 person years to the follow-up period.Healthcare professionals received a multifaceted antibiotic stewardship intervention consisting of a decision tool for appropriate antibiotic use, supported by a toolbox with educational materials. A participatory-action-research approach was used for implementation, with sessions for education, evaluation, and local tailoring of the intervention. The control group provided care as usual.The primary outcome was the number of antibiotic prescriptions for suspected urinary tract infections per person year. Secondary outcomes included the incidence of complications, all cause hospital referrals, all cause hospital admissions, all cause mortality within 21 days after suspected urinary tract infections, and all cause mortality.The numbers of antibiotic prescriptions for suspected urinary tract infections in the follow-up period were 54 prescriptions in 202 person years (0.27 per person year) in the intervention group and 121 prescriptions in 209 person years (0.58 per person year) in the usual care group. Participants in the intervention group had a lower rate of receiving an antibiotic prescription for a suspected urinary tract infection compared with participants in the usual care group, with a rate ratio of 0.42 (95% confidence interval 0.26 to 0.68). No differences between intervention and control group were observed in the incidence of complications (<0.01 v 0.05 per person year), hospital referrals (<0.01 v 0.05), admissions to hospital (0.01 v 0.05), and mortality (0 v 0.01) within 21 days after suspected urinary tract infections, nor in all cause mortality (0.26 v 0.26).Implementation of a multifaceted antibiotic stewardship intervention safely reduced antibiotic prescribing for suspected urinary tract infections in frail older adults.ClinicalTrials.gov NCT03970356.
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| 9. |
- Hartman, E. A. R., et al.
(författare)
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Multifaceted antibiotic stewardship intervention using a participatory-action-research approach to improve antibiotic prescribing for urinary tract infections in frail elderly (ImpresU): study protocol for a European qualitative study followed by a pragmatic cluster randomised controlled trial
- 2021
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Ingår i: Bmj Open. - : BMJ. - 2044-6055. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Almost 60% of antibiotics in frail elderly are prescribed for alleged urinary tract infections (UTIs). A substantial part of this comprises prescriptions in case of non-specific symptoms or asymptomatic bacteriuria, for which the latest guidelines promote restrictiveness with antibiotics. We aim to reduce inappropriate antibiotic use for UTIs through an antibiotic stewardship intervention (ASI) that encourages to prescribe according to these guidelines. To develop an effective ASI, we first need a better understanding of the complex decision-making process concerning suspected UTIs in frail elderly. Moreover, the implementation approach requires tailoring to the heterogeneous elderly care setting. Methods and analysis First, we conduct a qualitative study to explore factors contributing to antibiotic prescribing for UTIs in frail elderly, using semi-structured interviews with general practitioners, nursing staff, patients and informal caregivers. Next, we perform a pragmatic cluster randomised controlled trial in elderly care organisations. A multifaceted ASI is implemented in the intervention group; the control group receives care as usual. The ASI is centred around a decision tool that promotes restrictive antibiotic use, supported by a toolbox with educational materials. For the implementation, we use a modified participatory-action-research approach, guided by the results of the qualitative study. The primary outcome is the number of antibiotic prescriptions for suspected UTIs. We aim to recruit 34 clusters with in total 680 frail elderly residents >= 70 years. Data collection takes place during a 5-month baseline period and a 7-month follow-up period. Finally, we perform a process evaluation. The study has been delayed for 6 months due to COVID-19 and is expected to end in July 2021. Ethics and dissemination Ethical approvals and/or waivers were obtained from the ethical committees in Poland, the Netherlands, Norway and Sweden. The results will be disseminated through publication in peer-reviewed journals and conference presentations.
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| 10. |
- Villanova, Valeria, et al.
(författare)
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Boosting Biomass Quantity and Quality by Improved Mixotrophic Culture of the Diatom Phaeodactylum tricornutum
- 2021
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Diatoms are photoautotrophic unicellular algae and are among the most abundant, adaptable, and diverse marine phytoplankton. They are extremely interesting not only for their ecological role but also as potential feedstocks for sustainable biofuels and high-value commodities such as omega fatty acids, because of their capacity to accumulate lipids. However, the cultivation of microalgae on an industrial scale requires higher cell densities and lipid accumulation than those found in nature to make the process economically viable. One of the known ways to induce lipid accumulation in Phaeodactylum tricornutum is nitrogen deprivation, which comes at the expense of growth inhibition and lower cell density. Thus, alternative ways need to be explored to enhance the lipid production as well as biomass density to make them sustainable at industrial scale. In this study, we have used experimental and metabolic modeling approaches to optimize the media composition, in terms of elemental composition, organic and inorganic carbon sources, and light intensity, that boost both biomass quality and quantity of P. tricornutum. Eventually, the optimized conditions were scaled-up to 2 L photobioreactors, where a better system control (temperature, pH, light, aeration/mixing) allowed a further improvement of the biomass capacity of P. tricornutum to 12 g/L.
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