- ID:
- ivo://CDS.VizieR/J/A+A/506/1469
- Title:
- theta Cyg radial velocity variations
- Short Name:
- J/A+A/506/1469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the frame of the search for extrasolar planets and brown dwarfs around early-type main-sequence stars, we present the results obtained on the early F-type star theta Cygni. ELODIE and SOPHIE at Observatoire de Haute-Provence (OHP) were used to obtain 91 and 162 spectra, respectively. Our dedicated radial-velocity measurement method was used to monitor the star's radial velocities over five years. We also use complementary, high angular resolution and high-contrast images taken with PUEO at CFHT. We show that theta Cygni radial velocities are quasi-periodically variable, with a ~150-day period. These variations are not due to the ~0.35M_{sun}_ stellar companion that we detected in imaging at more than 46AU from the star. The absence of correlation between the bisector velocity span variations and the radial velocity variations for this 7km/s vsini star, as well as other criteria indicate that the observed radial velocity variations are not due to stellar spots. The observed amplitude of the bisector velocity span variations also seems to rule out stellar pulsations. However, we observe a peak in the bisector velocity span periodogram at the same period as the one found in the radial velocity periodogram, which indicates a probable link between these radial velocity variations and the low amplitude lineshape variations which are of stellar origin. Long-period variations are not expected from this type of star to our knowledge. If a stellar origin (hence of new type) was to be confirmed for these long-period radial velocity variations, this would have several consequences on the search for planets around main-sequence stars, both in terms of observational strategy and data analysis. An alternative explanation for these variable radial velocities is the presence of at least one planet of a few Jupiter masses orbiting at less than 1AU; however this planet alone does not explain all observed features, and the theta Cygni system is obviously more complex than a planetary system with 1 or 2 planets. The available data do not allow to distinguish between these two possible origins. A vigourous follow-up in spectroscopy and photometry is needed to get a comprehensive view of the star intrinsic variability and/or its surrounding planetary system.
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- ID:
- ivo://CDS.VizieR/J/ApJ/838/150
- Title:
- The Taurus-Auriga ecosystem. I.
- Short Name:
- J/ApJ/838/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The census of Taurus-Auriga has been assembled over seven decades and inherited the biases and incompleteness of the input studies. The unusual shape of its inferred initial mass function (IMF) and the existence of isolated disk-bearing stars suggest that additional (likely disk-free) members remain to be discovered. We therefore have begun a global reassessment of the census of Taurus-Auriga that exploits new data and better definitions of youth and kinematic membership. As a first step, we reconsider the membership of all disk-free candidate members from the literature with spectral type >=F0, 3h50min<{alpha}5h40min, and 14{deg}<{delta}<34{deg}. We combine data from the literature with Keck/HIRES and UH88/SNIFS spectra to test the membership of these candidates using the positions in the Hertzsprung-Russel diagram, proper motions, radial velocities, H{alpha}, lithium, and surface gravity. We find 218 confirmed or likely Taurus members, 160 confirmed or likely interlopers, and only 18 that lack sufficient evidence to draw firm conclusions. A significant fraction of these stars (81/218=37%) are not included in the most recent canonical member lists. There are few additional members to the immediate vicinity of the molecular clouds, preserving the IMFs that have been deemed anomalous in past work. Many of the likely Taurus members are instead distributed broadly across the search area. When combined with the known disk hosts, our updated census reveals two regimes: a high-density population with a high disk fraction (indicative of youth) that broadly traces the molecular clouds, and a low-density population with low disk fraction (hence likely older) that most likely represents previous generations of star formation.
- ID:
- ivo://CDS.VizieR/J/A+AS/125/497
- Title:
- Theta Vir and 109 Vir uvby photometry
- Short Name:
- J/A+AS/125/497
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are used to examine the possible variability of the spectrophotometric standards {theta} Vir and 109 Vir. No evidence is found for variability within a season of observation. Small year to year differences are most likely due to unaccounted for extinction changes.
- ID:
- ivo://CDS.VizieR/J/ApJ/874/L8
- Title:
- The TESS Habitable Zone Star Catalog
- Short Name:
- J/ApJ/874/L8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Transiting Exoplanet Survey Satellite (TESS) Habitable Zone Stars Catalog, a list of 1822 nearby stars with a TESS magnitude brighter than T=12 and reliable distances from Gaia DR2, around which the NASA's TESS mission can detect transiting planets, which receive Earth-like irradiation. For all those stars TESS is sensitive down to 2 Earth radii transiting planets during one transit. For 408 stars TESS can detect such planets down to 1 Earth-size during one transit. For 1690 stars, TESS has the sensitivity to detect planets down to 1.6 times Earth-size, a commonly used limit for rocky planets in the literature, receiving Earth-analog irradiation. We select stars from the TESS Candidate Target List, based on TESS Input Catalog Version 7. We update their distances using Gaia Data Release 2, and determine whether the stars will be observed for long enough during the 2yr prime mission to probe their Earth-equivalent orbital distance for transiting planets. We discuss the subset of 227 stars for which TESS can probe the full extent of the Habitable Zone, the full region around a star out to about a Mars-equivalent orbit. Observing the TESS Habitable Zone Catalog Stars will also give us deeper insight into the occurrence rate of planets, out to Earth-analog irradiation as well as in the Habitable Zone, especially around cool stars. We present the stars by decreasing angular separation of the 1 au equivalent distance to provide insights into which stars to prioritize for ground-based follow-up observations with upcoming extremely large telescopes.
- ID:
- ivo://CDS.VizieR/J/AJ/156/102
- Title:
- The TESS Input Catalog and Candidate Target List
- Short Name:
- J/AJ/156/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) will be conducting a nearly all-sky photometric survey over two years, with a core mission goal to discover small transiting exoplanets orbiting nearby bright stars. It will obtain 30 minute cadence observations of all objects in the TESS fields of view, along with two-minute cadence observations of 200000-400000 selected stars. The choice of which stars to observe at the two-minute cadence is driven by the need to detect small transiting planets, which leads to the selection of primarily bright, cool dwarfs. We describe the catalogs assembled and the algorithms used to populate the TESS Input Catalog (TIC), including plans to update the TIC with the incorporation of the Gaia second data release (Cat. I/345) in the near future. We also describe a ranking system for prioritizing stars according to the smallest transiting planet detectable, and assemble a Candidate Target List (CTL) using that ranking. We discuss additional factors that affect the ability to photometrically detect and dynamically confirm small planets, and we note additional stellar populations of interest that may be added to the final target list. The TIC is available on the STScI MAST server, and an enhanced CTL is available through the Filtergraph data visualization portal system at the URL http://filtergraph.vanderbilt.edu/tess_ctl.
- ID:
- ivo://CDS.VizieR/J/AJ/159/241
- Title:
- The TESS-Keck Survey. I. HD332231 Radial Velocities
- Short Name:
- J/AJ/159/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of a Saturn-size exoplanet orbiting HD332231 (TOI1456) in light curves from the Transiting Exoplanet Survey Satellite (TESS). HD332231 an F8 dwarf star with a V-band magnitude of 8.56 was observed by TESS in Sectors 14 and 15. We detect a single-transit event in the Sector 15 presearch data conditioning (PDC) light curve. We obtain spectroscopic follow up observations of HD332231 with the Automated Planet Finder (APF), Keck I, and Spatial Observations Network Group (SONG) telescopes. The orbital period we infer from radial velocity (RV) observations leads to the discovery of another transit in Sector 14 that was masked by PDC due to scattered light contamination. A joint analysis of the transit and RV data confirms the planetary nature of HD332231b, a Saturn-size (0.867_-0.025_^+0.027^R_J_), sub-Saturn-mass (0.244{+/-}0.021M_J_) exoplanet on a 18.71day circular orbit. The low surface gravity of HD332231b and the relatively low stellar flux it receives make it a compelling target for transmission spectroscopy. Also, the stellar obliquity is likely measurable via the Rossiter-McLaughlin effect, an exciting prospect given the 0.14au orbital separation of HD332231b. The spectroscopic observations do not provide substantial evidence for any additional planets in the HD332231 system, but continued RV monitoring is needed to further characterize this system. We also predict that the frequency and duration of masked data in the PDC light curves for TESS Sectors 14-16 could hide transits of some exoplanets with orbital periods between 10.5 and 17.5days.
- ID:
- ivo://CDS.VizieR/J/AJ/161/56
- Title:
- The TESS-Keck Survey. II. RVs of TOI-561
- Short Name:
- J/AJ/161/56
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- We report the discovery of TOI-561, a multiplanet system in the galactic thick disk that contains a rocky, ultra-short-period planet. This bright (V=10.2) star hosts three small transiting planets identified in photometry from the NASA TESS mission: TOI-561b (TOI-561.02, P=0.44days, Rp=1.45{+/-}0.11R{Earth}), c (TOI-561.01, P=10.8days, Rp=2.90{+/-}0.13R{Earth}), and d (TOI-561.03, P=16.3days, Rp=2.32{+/-}0.16R{Earth}). The star is chemically ([Fe/H]=-0.41{+/-}0.05, [{alpha}/Fe]=+0.23{+/-}0.05) and kinematically consistent with the galactic thick-disk population, making TOI-561 one of the oldest (10{+/-}3Gyr) and most metal-poor planetary systems discovered yet. We dynamically confirm planets b and c with radial velocities from the W.M.Keck Observatory High Resolution Echelle Spectrometer. Planet b has a mass and density of 3.2{+/-}0.8M{Earth} and 5.5_-1.6_^+2.0^g/cm^3^, consistent with a rocky composition. Its lower- than-average density is consistent with an iron-poor composition, although an Earth-like iron-to-silicates ratio is not ruled out. Planet c is 7.0{+/-}2.3M{Earth} and 1.6{+/-}0.6g/cm^3^, consistent with an interior rocky core overlaid with a low-mass volatile envelope. Several attributes of the photometry for planet d (which we did not detect dynamically) complicate the analysis, but we vet the planet with high-contrast imaging, ground-based photometric follow-up, and radial velocities. TOI-561b is the first rocky world around a galactic thick-disk star confirmed with radial velocities and one of the best rocky planets for thermal emission studies.
- ID:
- ivo://CDS.VizieR/J/AJ/161/119
- Title:
- The TESS-Keck survey. IV. Rvel for WASP-107
- Short Name:
- J/AJ/161/119
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- We measured the Rossiter-McLaughlin effect of WASP-107b during a single transit with Keck/HIRES. We found the sky-projected inclination of WASP-107b's orbit, relative to its host star's rotation axis, to be |{lambda}|=118_-19_^+38^degrees. This confirms the misaligned/polar orbit that was previously suggested from spot-crossing events and adds WASP-107b to the growing population of hot Neptunes in polar orbits around cool stars. WASP-107b is also the fourth such planet to have a known distant planetary companion. We examined several dynamical pathways by which this companion could have induced such an obliquity in WASP-107b. We find that nodal precession and disk dispersal-driven tilting can both explain the current orbital geometry while Kozai-Lidov cycles are suppressed by general relativity. While each hypothesis requires a mutual inclination between the two planets, nodal precession requires a much larger angle, which for WASP-107 is on the threshold of detectability with future Gaia astrometric data. As nodal precession has no stellar type dependence, but disk dispersal-driven tilting does, distinguishing between these two models is best done on the population level. Finding and characterizing more extrasolar systems like WASP-107 will additionally help distinguish whether the distribution of hot-Neptune obliquities is a dichotomy of aligned and polar orbits or if we are uniformly sampling obliquities during nodal precession cycles.
- ID:
- ivo://CDS.VizieR/J/ApJS/186/1
- Title:
- The 4th IBIS/ISGRI soft gamma-ray survey catalog
- Short Name:
- J/ApJS/186/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we report on the fourth soft gamma-ray source catalog obtained with the IBIS gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 70Ms of high-quality observations performed during the first five and a half years of the Core Program and public observations. Compared to previous IBIS surveys, this catalog includes a substantially increased coverage of extragalactic fields, and comprises more than 700 high-energy sources detected in the energy range 17-100keV, including both transients and faint persistent objects that can only be revealed with longer exposure times. A comparison is provided with the latest Swift/BAT survey results.
- ID:
- ivo://CDS.VizieR/VIII/37
- Title:
- The Third Bologna Survey (B3)
- Short Name:
- VIII/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains the first section of a sky survey performed at 408MHz with the 'Northern Cross' Radiotelescope. It contains about 13.000 radiosources. Although sources down to about 70mJy were measured, only sources brighter than 0.10Jy are retained in the catalogue. According to our estimate of confusion errors, this corresponds to a detection threshold of about 5{sigma}. The list is meant to include all the sources with a measured flux S>0.10Jy, in the sky area included between the declinations +37{deg}15' and +47{deg}37', epoch 1978.0. A number of zones however are affected by interferences, malfunctions, etc. The principal one is centered about the radiosource Cyg A, which is itself in the map, but not in the catalogue. The zone between RA 19h30m to 20h30m is entirely lacking, due to strong confusion. In the zone from 19h00m to 19h30m and from 20h30m to 21h00m, only sources brighter than 0.75Jy are listed, and to this level the catalogue is espected to be complete. For detailed discussion of the completeness of the catalogue see the original publication cited above.