| 1. |
- Serrano, L. M., et al.
(författare)
-
The HD 93963 A transiting system: A 1.04d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 667
-
Tidskriftsartikel (refereegranskat)abstract
- We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (M-* = 1.109 +/- 0.043M(circle dot), R-* = 1.043 +/- 0.009 R-circle dot) in a visual binary system. We combined TESS and CHEOPS space-borne photometry with MuSCAT 2 ground-based photometry, 'Alopeke and PHARO high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and SOPHIE radial velocity measurements. We validated and spectroscopically confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with an orbital period of P-c approximate to 3.65 d that was reported to be a TESS object of interest (TOI) shortly after the release of Sector 22 data. HD 93963 A c has amass of M-c = 19.2 +/- 4.1 M-circle plus and a radius of R-c = 3.228 +/- 0.059 R-circle plus, implying a mean density of rho(c) = 3.1 +/- 0.7 g cm(-3). The inner object, HD 93963 A b, is a validated 1.04 d ultra-short period (USP) transiting super-Earth that we discovered in the TESS light curve and that was not listed as a TOI, owing to the low significance of its signal (TESS signal-to-noise ratio approximate to 6.7, TESS + CHEOPS combined transit depth D-b = 141.5(-8.3)(+8.5) ppm). We intensively monitored the star with CHEOPS by performing nine transit observations to confirm the presence of the inner planet and validate the system. HD 93963 A b is the first small (R-b = 1.35 +/- 0.042 R-circle plus) USP planet discovered and validated by TESS and CHEOPS. Unlike planet c, HD 93963 Ab is not significantly detected in our radial velocities (M-b = 7.8 +/- 3.2 M-circle plus). The two planets are on either side of the radius valley, implying that they could have undergone completely different evolution processes. We also discovered a linear trend in our Doppler measurements, suggesting the possible presence of a long-period outer planet. With a V-band magnitude of 9.2, HD 93963 A is among the brightest stars known to host a USP planet, making it one of the most favourable targets for precise mass measurement via Doppler spectroscopy and an important laboratory to test formation, evolution, and migration models of planetary systems hosting ultra-short period planets.
|
|
| 2. |
- Rezeli, Melinda, et al.
(författare)
-
Development of an MRM assay panel with application to biobank samples from patients with Myocardial Infarction.
- 2013
-
Ingår i: Journal of Proteomics. - : Elsevier BV. - 1874-3919. ; 87:1, s. 16-25
-
Tidskriftsartikel (refereegranskat)abstract
- As part of a Swedish national cardiological research initiative, the development of a quantitative MRM assay is reported for the quantification of eleven putative cardiovascular disease markers. Within the study, patient samples from the LUNDHEARTGENE biobank were processed and nanoLC-MS/MS analysis were performed together with stable isotope dilution strategy for absolute quantification of the target proteins. Excellent linear regressions were achieved for 9 of the 11 peptides with LOQ ranged in the attomolar range. We have utilized the assay for the screening of plasma samples from patients with chest pain, and performed a comparative analysis of patients with ST Segment Elevation Myocardial Infarction and chest pain due to other causes. The assay demonstrates high reproducibility and correlate with clinical findings. Strong correlations were found for several of the apolipoproteins and their respective lipid subfractions (LDL, HDL or triglycerides). ApoC1, apoC2 and apoE were elevated in patients with STEMI. BIOLOGICAL SIGNIFICANCE: MRM assay were developed for putative cardiovascular disease markers as target proteins, and applied to biobanking sample material. The comparative analysis of patients with ST Segment Elevation Myocardial Infarction and chest pain due to other causes shows elevated levels of apoC1, apoC2 and apoE in patients with STEMI. These observations raise interesting novel hypotheses about the role of apolipoproteins C1, C2 and E in the pathophysiology of acute myocardial infarction, which merits further studies.
|
|
| 3. |
- Bonfanti, A., et al.
(författare)
-
TOI-1055 b: Neptunian planet characterised with HARPS, TESS, and CHEOPS
- 2023
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 671
-
Tidskriftsartikel (refereegranskat)abstract
- Context. TOI-1055 is a Sun-like star known to host a transiting Neptune-sized planet on a 17.5-day orbit (TOI-1055 b). Radial velocity (RV) analyses carried out by two independent groups using nearly the same set of HARPS spectra have provided measurements of planetary masses that differ by ∼2σ. Aims. Our aim in this work is to solve the inconsistency in the published planetary masses by significantly extending the set of HARPS RV measurements and employing a new analysis tool that is able to account and correct for stellar activity. Our further aim was to improve the precision on measurements of the planetary radius by observing two transits of the planet with the CHEOPS space telescope. Methods. We fit a skew normal function to each cross correlation function extracted from the HARPS spectra to obtain RV measurements and hyperparameters to be used for the detrending. We evaluated the correlation changes of the hyperparameters along the RV time series using the breakpoint technique. We performed a joint photometric and RV analysis using a Markov chain Monte Carlo scheme to simultaneously detrend the light curves and the RV time series. Results. We firmly detected the Keplerian signal of TOI-1055 b, deriving a planetary mass of Mb = 20.4-2.5+2.6 MO (∼12%). This value is in agreement with one of the two estimates in the literature, but it is significantly more precise. Thanks to the TESS transit light curves combined with exquisite CHEOPS photometry, we also derived a planetary radius of Rb = 3.490-0.064+0.070 RO (∼1.9%). Our mass and radius measurements imply a mean density of ρb = 2.65-0.35+0.37 g cm-3 (∼14%). We further inferred the planetary structure and found that TOI-1055 b is very likely to host a substantial gas envelope with a mass of 0.41-0.20+0.34 MO and a thickness of 1.05-0.29+0.30 RO. Conclusions. Our RV extraction combined with the breakpoint technique has played a key role in the optimal removal of stellar activity from the HARPS time series, enabling us to solve the tension in the planetary mass values published so far for TOI-1055 b.
|
|
| 4. |
- Bourrier, V., et al.
(författare)
-
A CHEOPS-enhanced view of the HD 3167 system
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 668
-
Tidskriftsartikel (refereegranskat)abstract
- Much remains to be understood about the nature of exoplanets smaller than Neptune, most of which have been discovered in compact multi-planet systems. With its inner ultra-short period planet b aligned with the star and two larger outer planets d-c on polar orbits, the multi-planet system HD 3167 features a peculiar architecture and offers the possibility to investigate both dynamical and atmospheric evolution processes. To this purpose we combined multiple datasets of transit photometry and radial velocimetry (RV) to revise the properties of the system and inform models of its planets. This effort was spearheaded by CHEOPS observations of HD 3167b, which appear inconsistent with a purely rocky composition despite its extreme irradiation. Overall the precision on the planetary orbital periods are improved by an order of magnitude, and the uncertainties on the densities of the transiting planets b and c are decreased by a factor of 3. Internal structure and atmospheric simulations draw a contrasting picture between HD 3167d, likely a rocky super-Earth that lost its atmosphere through photo-evaporation, and HD 3167c, a mini-Neptune that kept a substantial primordial gaseous envelope. We detect a fourth, more massive planet on a larger orbit, likely coplanar with HD 3167d-c. Dynamical simulations indeed show that the outer planetary system d-c-e was tilted, as a whole, early in the system history, when HD 3167b was still dominated by the star influence and maintained its aligned orbit. RV data and direct imaging rule out that the companion that could be responsible for the present-day architecture is still bound to the HD 3167 system. Similar global studies of multi-planet systems will tell how many share the peculiar properties of the HD 3167 system, which remains a target of choice for follow-up observations and simulations.
|
|
| 5. |
- Harre, J. V., et al.
(författare)
-
Examining the orbital decay targets KELT-9 b, KELT-16 b, and WASP-4 b, and the transit-timing variations of HD 97658 b
- 2023
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 669
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Tidal orbital decay is suspected to occur for hot Jupiters in particular, with the only observationally confirmed case of this being WASP-12 b. By examining this effect, information on the properties of the host star can be obtained using the so-called stellar modified tidal quality factor Q′∗, which describes the efficiency with which the kinetic energy of the planet is dissipated within the star. This can provide information about the interior of the star. Aims. In this study, we aim to improve constraints on the tidal decay of the KELT-9, KELT-16, and WASP-4 systems in order to find evidence for or against the presence of tidal orbital decay. With this, we want to constrain the Q′∗ value for each star. In addition, we aim to test the existence of the transit timing variations (TTVs) in the HD 97658 system, which previously favoured a quadratic trend with increasing orbital period. Methods. Making use of newly acquired photometric observations from CHEOPS (CHaracterising ExOplanet Satellite) and TESS (Transiting Exoplanet Survey Satellite), combined with archival transit and occultation data, we use Markov chain Monte Carlo (MCMC) algorithms to fit three models to the data, namely a constant-period model, an orbital-decay model, and an apsidal-precession model. Results. We find that the KELT-9 system is best described by an apsidal-precession model for now, with an orbital decay trend at over 2 σ being a possible solution as well. A Keplerian orbit model with a constant orbital period provides the best fit to the transit timings of KELT-16 b because of the scatter and scale of their error bars. The WASP-4 system is best represented by an orbital decay model at a 5 σ significance, although apsidal precession cannot be ruled out with the present data. For HD 97658 b, using recently acquired transit observations, we find no conclusive evidence for a previously suspected strong quadratic trend in the data.
|
|
| 6. |
- Maxted, P. F. L., et al.
(författare)
-
Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops
- 2022
-
Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 514:1, s. 77-104
-
Tidskriftsartikel (refereegranskat)abstract
- CHEOPS (CHaracterising ExOPlanet Satellite) is an ESA S-class mission that observes bright stars at high cadence from low-Earth orbit. The main aim of the mission is to characterize exoplanets that transit nearby stars using ultrahigh precision photometry. Here, we report the analysis of transits observed by CHEOPS during its Early Science observing programme for four well-known exoplanets: GJ 436 b, HD 106315 b, HD 97658 b, and GJ 1132 b. The analysis is done using pycheops, an open-source software package we have developed to easily and efficiently analyse CHEOPS light-curve data using state-of-the-art techniques that are fully described herein. We show that the precision of the transit parameters measured using CHEOPS is comparable to that from larger space telescopes such as Spitzer Space Telescope and Kepler. We use the updated planet parameters from our analysis to derive new constraints on the internal structure of these four exoplanets.
|
|
| 7. |
- Strandberg, Gustav, 1977-, et al.
(författare)
-
High-resolution regional simulation of last glacial maximum climate in Europe
- 2011
-
Ingår i: Tellus. Series A, Dynamic meteorology and oceanography. - : Stockholm University Press. - 0280-6495 .- 1600-0870. ; 63:1, s. 107-125
-
Tidskriftsartikel (refereegranskat)abstract
- A fully coupled atmosphere-ocean general circulation model is used to simulate climate conditions during the last glacial maximum (LGM). Forcing conditions include astronomical parameters, greenhouse gases, ice sheets and vegetation. A 50-yr period of the global simulation is dynamically downscaled to 50 km horizontal resolution over Europe with a regional climate model (RCM). A dynamic vegetation model is used to produce vegetation that is consistent with the climate simulated by the RCM. This vegetation is used in a final simulation with the RCM. The resulting climate is 5-10 degrees C colder than the recent past climate (representative of year 1990) over ice-free parts of Europe as an annual average; over the ice-sheet up to 40 degrees C colder in winter." The average model-proxy error is about the same for summer and winter, for pollen-based proxies. The RCM results are within (outside) the uncertainty limits for winter (summer). Sensitivity studies performed with the RCM indicate that the simulated climate is sensitive to changes in vegetation, whereas the location of the ice sheet only affects the climate around the ice sheet. The RCM-simulated interannual variability in near surface temperature is significantly larger at LGM than in the recent past climate.
|
|
