- ID:
- ivo://CDS.VizieR/J/MNRAS/443/2391
- Title:
- Light curves of Qatar-2 transit events
- Short Name:
- J/MNRAS/443/2391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 17 high-precision light curves of five transits of the planet Qatar-2 b, obtained from four defocused 2m-class telescopes. Three of the transits were observed simultaneously in the Sloan g'r'i'z' passbands using the seven-beam Gamma Ray Burst Optical and Near-Infrared Detector imager on the MPG/ESO 2.2m telescope. A fourth was observed simultaneously in Gunn grz using the Centro Astronomico Hispano Aleman 2.2m telescope with Bonn University Simultaneous Camera, and in r using the Cassini 1.52m telescope. Every light curve shows small anomalies due to the passage of the planetary shadow over a cool spot on the surface of the host star. We fit the light curves with the prism+gemc model to obtain the photometric parameters of the system and the position, size and contrast of each spot. We use these photometric parameters and published spectroscopic measurements to obtain the physical properties of the system to high precision, finding a larger radius and lower density for both star and planet than previously thought. By tracking the change in position of one star-spot between two transit observations, we measure the orbital obliquity of Qatar-2b to be lambda=4.3{deg}+/-4.5{deg}, strongly indicating an alignment of the stellar spin with the orbit of the planet. We calculate the rotation period and velocity of the cool host star to be 11.5+/-0.2d and 3.28+/-0.04km/s at a colatitude of 74{deg}. We assemble the planet's transmission spectrum over the 386-976 nm wavelength range and search for variations of the measured radius of Qatar-2 b as a function of wavelength. Our analysis highlights a possible H_2_/He Rayleigh scattering in the blue.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/465/843
- Title:
- Light curves of WASP-52
- Short Name:
- J/MNRAS/465/843
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 13 high-precision light curves of eight transits of the exoplanet WASP-52 b, obtained by using four medium-class telescopes, through different filters, and adopting the defocussing technique. One transit was recorded simultaneously from two different observatories and another one from the same site but with two different instruments, including a multiband camera. Anomalies were clearly detected in five light curves and modelled as star-spots occulted by the planet during the transit events. We fitted the clean light curves with the JKTEBOP code, and those with the anomalies with the PRISM+gemc codes in order to simultaneously model the photometric parameters of the transits and the position, size and contrast of each star-spot. We used these new light curves and some from the literature to revise the physical properties of the WASP-52 system. Star-spots with similar characteristics were detected in four transits over a period of 43 d. In the hypothesis that we are dealing with the same star-spot, periodically occulted by the transiting planet, we estimated the projected orbital obliquity of WASP-52 b to be {lambda}=3.8+/-8.4{deg}. We also determined the true orbital obliquity, {psi}=20+/-50{deg}, which is, although very uncertain, the first measurement of {psi} purely from star-spot crossings. We finally assembled an optical transmission spectrum of the planet and searched for variations of its radius as a function of wavelength. Our analysis suggests a flat transmission spectrum within the experimental uncertainties.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A30
- Title:
- Light curves of WASP-3b
- Short Name:
- J/A+A/549/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The TASTE project is searching for low-mass planets with the transit timing variation (TTV) technique by gathering high-precision, short-cadence light curves for a selected sample of transiting exoplanets. It has been claimed that the "hot Jupiter" WASP-3b could be perturbed by a second planet. Presenting eleven new light curves (secured at the IAC80 and UDEM telescopes) and re-analyzing thirty-eight archival light curves in a homogeneous way, we show that new data do not confirm the previously claimed TTV signal. However, we bring evidence that measurements are not consistent with a constant orbital period, though no significant periodicity can be detected. Additional dynamical modeling and follow-up observations are planned to constrain the properties of the perturber or to put upper limits to it. We provide a refined ephemeris for WASP-3b and improved orbital/physical parameters. A contact eclipsing binary, serendipitously discovered among field stars, is reported here for the first time.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A127
- Title:
- Light curves of WASP-67 transit events
- Short Name:
- J/A+A/568/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The extrasolar planet WASP-67 b is the first hot Jupiter definitively known to undergo only partial eclipses. The lack of the second and third contact points in this planetary system makes it difficult to obtain accurate measurements of its physical parameters. Aims. By using new high-precision photometric data, we confirm that WASP-67 b shows grazing eclipses and compute accurate estimates of the physical properties of the planet and its parent star. Methods. We present high-quality, multi-colour, broad-band photometric observations comprising five light curves covering two transit events, obtained using two medium-class telescopes and the telescope-defocussing technique. One transit was observed through a Bessel-R filter and the other simultaneously through filters similar to Sloan griz. We modelled these data using jktebop. The physical parameters of the system were obtained from the analysis of these light curves and from published spectroscopic measurements. Results. All five of our light curves satisfy the criterion for being grazing eclipses. We revise the physical parameters of the whole WASP-67 system and, in particular, significantly improve the measurements of the planet's radius and density as compared to the values in the discovery paper. The transit ephemeris was also substantially refined. We investigated the variation of the planet's radius as a function of the wavelength, using the simultaneous multi-band data, finding that our measurements are consistent with a flat spectrum to within the experimental uncertainties.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A126
- Title:
- Light curves of WASP-80 transit events
- Short Name:
- J/A+A/562/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- WASP-80 is one of only two systems known to contain a hot Jupiter which transits its M-dwarf host star. We present eight light curves of one transit event, obtained simultaneously using two defocussed telescopes. These data were taken through the Bessell I, Sloan g'r'i'z' and near-infrared JHK passbands. We use our data to search for opacity-induced changes in the planetary radius, but find that all values agree with each other. Our data are therefore consistent with a flat transmission spectrum to within the observational uncertainties. We also measure an activity index of the host star of logR'_HK=-4.495, meaning that WASP-80A shows strong chromospheric activity. The non-detection of starspots implies that, if they exist, they must be small and symmetrically distributed on the stellar surface. We model all available optical transit light curves and obtain improved physical properties and orbital ephemerides for the system.
- ID:
- ivo://CDS.VizieR/J/A+A/588/A81
- Title:
- Line list and abundances of the binary zet2 Ret
- Short Name:
- J/A+A/588/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore condensation temperature Tc trends in the binary system zet1 Ret - zet2 Ret, to determine whether there is a depletion of refractories, which could be related to the planet formation process. The star zet2 Ret hosts a debris disk which was detected by an IR excess and confirmed by direct imaging and numerical simulations, while zet1 Ret does not present IR excess nor planets. We derived differential abundances of 24 different species with equivalent widths and spectral synthesis. The star zet1 Ret resulted slightly more metal rich than zet2 Ret by 0.02dex, and the relative abundances showed a positive Tc trend. Then, we propose an scenario in which the refractory elements depleted in zet2 Ret are possibly locked-up in the rocky material that orbits this star and produce the debris disk observed around this object.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/46
- Title:
- Lithium abundances in HIP stars
- Short Name:
- J/ApJ/756/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive atmospheric parameters and lithium abundances for 671 stars and include our measurements in a literature compilation of 1381 dwarf and subgiant stars. First, a "lithium desert" in the effective temperature (T_eff_) versus lithium abundance (A_Li_) plane is observed such that no stars with T_eff_=~6075K and A_Li_=~1.8 are found. We speculate that most of the stars on the low A_Li_ side of the desert have experienced a short-lived period of severe surface lithium destruction as main-sequence or subgiant stars. Next, we search for differences in the lithium content of thin-disk and thick-disk stars, but we find that internal processes have erased from the stellar photospheres their possibly different histories of lithium enrichment. Nevertheless, we note that the maximum lithium abundance of thick-disk stars is nearly constant from [Fe/H]=-1.0 to -0.1, at a value that is similar to that measured in very metal-poor halo stars (A_Li_=~2.2). Finally, differences in the lithium abundance distribution of known planet-host stars relative to otherwise ordinary stars appear when restricting the samples to narrow ranges of T_eff_ or mass, but they are fully explained by age and metallicity biases. We confirm the lack of a connection between low lithium abundance and planets. However, we find that no low A_Li_ planet-hosts are found in the desert T_eff_ window. Provided that subtle sample biases are not responsible for this observation, this suggests that the presence of gas giant planets inhibit the mechanism responsible for the lithium desert.
- ID:
- ivo://CDS.VizieR/J/ApJ/724/154
- Title:
- Lithium abundances in stars with planets
- Short Name:
- J/ApJ/724/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work presents a homogeneous determination of lithium abundances in a large sample of giant-planet-hosting stars (N=117) and a control sample of disk stars without detected planets (N=145). The lithium abundances were derived using a detailed profile fitting of the LiI doublet at 6708{AA} in LTE. The planet-hosting and comparison stars were chosen to have significant overlap in their respective physical properties, including effective temperatures, luminosities, masses, metallicities, and ages. The combination of uniform data and homogeneous analysis with well-selected samples makes this study well suited to probe for possible differences in the lithium abundances found in planet-hosting stars. An overall comparison between the two samples reveals no obvious differences between stars with and without planets. A closer examination of the behavior of the Li abundances over a narrow range of effective temperature (5700K<=T_eff_<=5850K) indicates subtle differences between the two stellar samples; this temperature range is particularly sensitive to various physical processes that can deplete lithium.
- ID:
- ivo://CDS.VizieR/J/A+A/548/A90
- Title:
- Looking for the rainbow on exoplanets
- Short Name:
- J/A+A/548/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Looking for the primary rainbow in starlight that is reflected by exoplanets appears to be a promising method to search for liquid water clouds in exoplanetary atmospheres. Ice water clouds, that consist of water crystals instead of water droplets, could potentially mask the rainbow feature in the planetary signal by covering liquid water clouds. Here, we investigate the strength of the rainbow feature for exoplanets that have liquid and icy water clouds in their atmosphere, and calculate the rainbow feature for a realistic cloud coverage of Earth. We calculate flux and polarization signals of starlight that is reflected by horizontally and vertically inhomogeneous Earth-like exoplanets, covered by patchy clouds consisting of liquid water droplets or water ice crystals. The planetary surfaces are black.
- ID:
- ivo://CDS.VizieR/J/A+A/521/A19
- Title:
- 21 Lutetia UBVRI light curves
- Short Name:
- J/A+A/521/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroid 21 Lutetia is the second target of the Rosetta space mission. Extensive pre-encounter, space-, and ground-based observations are being performed to prepare for the flyby in July 2010. The aim of this article is to accurately characterize the photometric properties of this asteroid over a broad spectral range from the ultraviolet to the near-infrared and to search for evidence of surface inhomogeneities.