- ID:
- ivo://CDS.VizieR/J/A+A/628/A64
- Title:
- EPIC 212036875b griz light curves
- Short Name:
- J/A+A/628/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although more than 2000 brown dwarfs have been detected to date, mainly from direct imaging, their characterisation is difficult due to their faintness and model dependent results. In the case of transiting brown dwarfs it is, however, possible to make direct high precision observations. Our aim is to investigate the nature and formation of brown dwarfs by adding a new well-characterised object, in term of its mass, radius and bulk density, to the currently small sample of less than 20 transiting brown dwarfs. One brown dwarf candidate was found by the KESPRINT consortium when searching for exoplanets in the K2 space mission Campaign 16 field. We combined the K2 photometric data with a series of multi-colour photometric observations, imaging and radial velocity measurements to rule out false positive scenarios and to determine the fundamental properties of the system. We report the discovery and characterisation of a transiting brown dwarf in a 5.17 day eccentric orbit around the slightly evolved F7V star EPIC 212036875. EPIC 212036875b is a rare object that resides in the brown dwarf desert. In the mass-density diagram for planets, brown dwarfs and stars, we find that all giant planets and brown dwarfs follow the same trend from 0.3M_J_ to the turn-over to hydrogen burning stars at 73M_J_. EPIC 212036875b falls on the theoretical line for H/He dominated planets in this diagram as determined by interior structure models, as well as on the empirical fit. We argue that EPIC 212036875b formed via gravitational disc instabilities in the outer part of the disc, followed by a quick migration. Orbital tidal circularisation may have started early in its history for a brief period when the brown dwarf's radius was larger. The lack of spin-orbit synchronisation points to a weak stellar dissipation parameter which implies a circularisation timescale of 23Gyr, or suggests an interaction between the magnetic and tidal forces of the star and the brown dwarf.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/629/A80
- Title:
- ESPRESSO blind RV exoplanet survey catalog
- Short Name:
- J/A+A/629/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the main scientific drivers for ESPRESSO, Echelle SPectrograph, is the detection and characterization of Earth-class exoplanets. With this goal in mind, the ESPRESSO guaranteed time observations (GTO) Catalog identifies the best target stars for a blind search for the radial velocity (RV) signals caused by Earth-class exoplanets. Using the most complete stellar catalogs available, we screened for the most suitable G, K, and M dwarf stars for the detection of Earth-class exoplanets with ESPRESSO. For most of the stars, we then gathered high-resolution spectra from new observations or from archival data. We used these spectra to spectroscopically investigate the existence of any stellar binaries, both bound or background stars. We derived the activity level using chromospheric activity indexes using log (R'_HK_), as well as the projected rotational velocity vsini. For the cases where planet companions are already known, we also looked at the possibility that additional planets may exist in the host's habitable zone using dynamical arguments. We estimated the spectroscopic contamination level, vsini, activity, stellar parameters and chemical abundances for 249 of the most promising targets. Using these data, we selected 45 stars that match our criteria for detectability of a planet like Earth. The stars presented and discussed in this paper constitute the ESPRESSO GTO catalog for the RV blind search for Earth-class planets. They can also be used for any other work requiring a detailed spectroscopic characterization of stars in the solar neighborhood.
- ID:
- ivo://CDS.VizieR/J/AJ/156/276
- Title:
- Exoplanetary atmospheric properties with MIRI
- Short Name:
- J/AJ/156/276
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Mid-Infrared instrument (MIRI) on board the James Webb Space Telescope will perform the first ever characterization of young giant exoplanets observed by direct imaging in the 5-28 {mu}m spectral range. This wavelength range is key for both determining the bolometric luminosity of the cool known exoplanets and for accessing the strongest ammonia bands. In conjunction with shorter wavelength observations, MIRI will enable a more accurate characterization of the exoplanetary atmospheric properties. Here we consider a subsample of the currently known exoplanets detected by direct imaging, and we discuss their detectability with MIRI, either using the coronagraphic or the spectroscopic modes. By using the Exo-REM atmosphere model, we calculate the mid-infrared emission spectra of 14 exoplanets, and we simulate MIRI coronagraphic or spectroscopic observations. Specifically, we analyze four coronagraphic observational setups, which depend on (i) the target-star and reference-star offset (0, 3, 14 mas), (ii) the wavefront-error (130, 204 nm root mean square), and (iii) the telescope jitter amplitude (1.6, 7 mas). We then determine the signal-to-noise and integration time values for the coronagraphic targets whose planet-to-star contrasts range from 3.9 to 10.1 mag. We conclude that all the MIRI targets should be observable with different degrees of difficulty, which depends on the final in-flight instrument performances. Furthermore, we test for detection of ammonia in the atmosphere of the coolest targets. Finally, we present the case of HR 8799 b to discuss what MIRI observations can bring to the knowledge of a planetary atmosphere, either alone or in combination with shorter wavelength observations.
- ID:
- ivo://CDS.VizieR/J/ApJS/254/39
- Title:
- Exoplanet candidates from TESS first 2yr obs
- Short Name:
- J/ApJS/254/39
- Date:
- 03 Dec 2021 00:47:43
- Publisher:
- CDS
- Description:
- We present 2241 exoplanet candidates identified with data from the Transiting Exoplanet Survey Satellite (TESS) during its 2yr Prime Mission. We list these candidates in the TESS Objects of Interest (TOI) Catalog, which includes both new planet candidates found by TESS and previously known planets recovered by TESS observations. We describe the process used to identify TOIs, investigate the characteristics of the new planet candidates, and discuss some notable TESS planet discoveries. The TOI catalog includes an unprecedented number of small planet candidates around nearby bright stars, which are well suited for detailed follow-up observations. The TESS data products for the Prime Mission (sectors 1-26), including the TOI catalog, light curves, full-frame images, and target pixel files, are publicly available at the Mikulski Archive for Space Telescopes.
- ID:
- ivo://CDS.VizieR/J/AJ/159/154
- Title:
- Exoplanet candidates in Campaign 5 of the K2 mission
- Short Name:
- J/AJ/159/154
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- We present a uniform transiting exoplanet candidate list for Campaign 5 of the K2 mission. This catalog contains 75 planets with seven multi-planet systems (five double, one triple, and one quadruple planet system). Within the range of our search, we find eight previously undetected candidates, with the remaining 67 candidates overlapping 51% of the study of Kruse+, (2019, J/ApJS/244/11) that manually vets candidates from Campaign 5. In order to vet our potential transit signals, we introduce the Exoplanet Detection Identification Vetter (EDI-Vetter), which is a fully automated program able to determine whether a transit signal should be labeled as a false positive or a planet candidate. This automation allows us to create a statistically uniform catalog, ideal for measurements of planet occurrence rate. When tested, the vetting software is able to ensure that our sample is 94.2% reliable against systematic false positives. Additionally, we inject artificial transits at the light-curve level of the raw K2 data and find that the maximum completeness of our pipeline is 70% before vetting and 60% after vetting. For convenience of future studies of occurrence rate, we include measurements of stellar noise (CDPP; combined differential photometric precision --Christiansen+ 2012, J/PASP/124/1279) and the three-transit window function for each target.
- ID:
- ivo://CDS.VizieR/J/MNRAS/463/1780
- Title:
- Exoplanet candidates in Praesepe (M 44)
- Short Name:
- J/MNRAS/463/1780
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we keep pushing K2 data to a high photometric precision, close to that of the Kepler main mission, using a PSF-based, neighbour-subtraction technique, which also overcome the dilution effects in crowded environments. We analyse the open cluster M 44 (NGC 2632), observed during the K2 Campaign 5, and extract light curves of stars imaged on module 14, where most of the cluster lies. We present two candidate exoplanets hosted by cluster members and five by field stars. As a by-product of our investigation, we find 1680 eclipsing binaries and variable stars, 1071 of which are new discoveries. Among them, we report the presence of a heartbeat binary star. Together with this work, we release to the community a catalogue with the variable stars and the candidate exoplanets found, as well as all our raw and detrended light curves.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A156
- Title:
- Exoplanet host stars SPHERE multiplicity survey
- Short Name:
- J/A+A/649/A156
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We are studying the influence of stellar multiplicity on exoplanet systems and, in particular, systems that have been detected via radial-velocity searches. We are specifically interested in the closest companions as they would have a strong influence on the evolution of the original planet-forming disks. In this study, we present new companions that have been detected during our ongoing survey of exoplanet hosts with VLT/SPHERE (Spectro-Polarimetric High-Contrast Exoplanet Research). We are using the extreme adaptive optics imager SPHERE at the ESO/VLT to search for faint (sub)stellar companions. We utilized the classical coronagraphic imaging mode to perform a snapshot survey (3-6min integration time) of exoplanet host stars in the K_S_-band. We detected new stellar companions to the exoplanet host stars HD 1666, HIP 68468, HIP 107773, and HD 109271. With an angular separation of only 0.38arcsec (40au of projected separation), HIP 107773 is among the closest companions found for exoplanet host stars. The presence of the stellar companion explains the linear radial-velocity trend seen in the system. At such a small separation, the companion likely had a significant influence on the evolution of the planet-forming disk around the primary star. We find that the companion in the HD 1666 system may well be responsible for the high orbit eccentricity (0.63) of the detected Jupiter class planet, making this system one of only a few where such a connection can be established. A cross-match with the Gaia DR2 catalog shows, furthermore, that the near infrared faint companion around HD 109271 was detected in the optical and it is significantly brighter than in the near infrared, making it a white dwarf companion.
- ID:
- ivo://CDS.VizieR/J/A+A/613/A41
- Title:
- 5 exoplanet light and RV curves
- Short Name:
- J/A+A/613/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The measurement of the orbital obliquity of hot Jupiters, with different physical characteristics, can provide clues to the mechanisms of migration and orbital evolution of this particular class of giant exoplanets. We aim to derive the degree of alignment between planetary orbit and stellar spin angular momentum vectors and look for possible links with other orbital and fundamental physical parameters of the star-planet system. Here we focus on the characterisation of five transiting planetary systems (HAT-P-3, HAT-P-12, HAT-P-22, WASP-39 and WASP-60) and the determination of their sky-projected planet orbital obliquity through the measurement of the Rossiter-McLaughlin effect. We used HARPS-N high-precision radial velocity measurements, gathered during transit events, to measure the Rossiter-McLaughlin effect in the target systems and determine the sky-projected angle between the planetary orbital plane and the stellar equator. The characterisation of stellar atmospheric parameters was performed exploiting the HARPS-N spectra, using line equivalent width ratios, and spectral synthesis methods. Photometric parameters of the five transiting exoplanets were re-analysed through 17 new light curves, obtained with an array of medium-class telescopes, and other light curves from the literature. Survey-time-series photometric data were analysed for determining the rotation periods of the five stars and their spin inclination. From the analysis of the Rossiter-McLaughlin effect we derived a sky-projected obliquity of {lambda}=21.2+/-8.7{deg}, {lambda=-54^+41^_-13_{deg}, {lambda=-2.1+/-3.0{deg}, lambda=0+/-11{deg} and lambda=-129+/-17{deg} for HAT-P-3 b, HAT-P-12 b, HAT-P-22 b, WASP-39 b and WASP-60 b, respectively. The latter value indicates that WASP-60 b is moving on a retrograde orbit. These values represent the first measurements of {lambda} for the five exoplanetary systems under study. The stellar activity of HAT-P-22 indicates a rotation period of 28.7+/-0.4-days, which allowed us to estimate the true misalignment angle of HAT-P-22 b, {psi}=24+/-18{deg}. The revision of the physical parameters of the five exoplanetary systems returned values fully compatible with those existing in the literature, with the exception of the WASP-60 system, for which, based on higher quality spectroscopic and photometric data, we found a more massive and younger star, and a larger and hotter planet.
- ID:
- ivo://CDS.VizieR/J/AJ/159/211
- Title:
- Exoplanet parameters from Kepler and K2
- Short Name:
- J/AJ/159/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present calculations of the occurrence rate of small close-in planets around low-mass dwarf stars using the known planet populations from the Kepler and K2 missions. Applying completeness corrections clearly reveals the radius valley in the maximum a posteriori occurrence rates as a function of orbital separation and planet radius. We measure the slope of the valley to be r_p,valley_{prop}F^-0.060{+/-}0.025^, which bears the opposite sign from that measured around Sun-like stars, thus suggesting that thermally driven atmospheric mass loss may not dominate the evolution of planets in the low stellar mass regime or that we are witnessing the emergence of a separate channel of planet formation. The latter notion is supported by the relative occurrence of rocky to non-rocky planets increasing from 0.5{+/-}0.1 around mid-K dwarfs to 8.5{+/-}4.6 around mid-M dwarfs. Furthermore, the center of the radius valley at 1.54{+/-}0.16R{earth} is shown to shift to smaller sizes with decreasing stellar mass, in agreement with physical models of photoevaporation, core-powered mass loss, and gas-poor formation. Although current measurements are insufficient to robustly identify the dominant formation pathway of the radius valley, such inferences may be obtained by the Transiting Exoplanet Survey Satellite with O(85000) mid-to-late M dwarfs observed with 2minutes cadence. The measurements presented herein also precisely designate the subset of planetary orbital periods and radii that should be targeted in radial velocity surveys to resolve the rocky to non-rocky transition around low-mass stars.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A39
- Title:
- Exoplanets interior structures & Love numbers
- Short Name:
- J/A+A/615/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Space missions such as CoRoT and Kepler have made the transit method the most successful technique in observing extrasolar planets. However, although the mean density of a planet can be derived from its measured mass and radius, no details about its interior structure, such as the density profile, can be inferred so far. If determined precisely enough, the shape of the transiting light curve might, in principle, reveal the shape of the planet, and in particular, its deviation from spherical symmetry. These deformations are caused, for instance, by the tidal interactions of the planet with the host star and by other planets that might orbit in the planetary system. The deformations depend on the interior structure of the planet and its composition and can be parameterized as Love numbers k_n_. This means that the diversity of possible interior models for extrasolar planets might be confined by measuring this quantity. We present results of a wide-ranging parameter study in planet mass, surface temperature, and layer mass fractions on such models for super-Earths and their corresponding Love numbers. Based on these data, we find that k_2_ is most useful in assessing the ratio of rocky material to iron and in ruling out certain compositional configurations for measured mass and radius values, such as a prominent core consisting of rocky material. Furthermore, we apply the procedure to exoplanets K2-3b and c and predict that K2-3c probably has a thick outer water layer.
