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- ID:
- ivo://CDS.VizieR/J/A+A/501/297
- Title:
- Effective temperatures of B Supergiants
- Short Name:
- J/A+A/501/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Effective temperatures of early-type supergiants are important to test stellar atmosphere- and internal structure-models of massive and intermediate mass objects at different evolutionary phases. However, these Teff values are more or less discrepant depending on the method used to determine them. We aim to obtain a new calibration of the Teff parameter for early-type supergiants as a function of observational quantities that are: a) highly sensitive to the ionization balance in the photosphere and its gas pressure; b) independent of the interstellar extinction; c) as much as possible model-independent.
- ID:
- ivo://CDS.VizieR/J/AJ/156/83
- Title:
- Effect of stellar companions on planetary systems
- Short Name:
- J/AJ/156/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler light curves used to detect thousands of planetary candidates are susceptible to dilution due to blending with previously unknown nearby stars. With the automated laser adaptive optics instrument, Robo-AO, we have observed 620 nearby stars around 3857 planetary candidates host stars. Many of the nearby stars, however, are not bound to the KOI. We use galactic stellar models and the observed stellar density to estimate the number and properties of unbound stars. We estimate the spectral type and distance to 145 KOIs with nearby stars using multi-band observations from Robo-AO and Keck-AO. Most stars within 1" of a Kepler planetary candidate are likely bound, in agreement with past studies. We use likely bound stars and the precise stellar parameters from the California Kepler Survey to search for correlations between stellar binarity and planetary properties. No significant difference between the binarity fraction of single and multiple-planet systems is found, and planet hosting stars follow similar binarity trends as field stars, many of which likely host their own non-aligned planets. We find that hot Jupiters are ~4x more likely than other planets to reside in a binary star system. We correct the radius estimates of the planet candidates in characterized systems and find that for likely bound systems, the estimated planetary radii will increase on average by a factor of 1.77, if either star is equally likely to host the planet. Lastly, we find the planetary radius gap is robust to the impact of dilution.
- ID:
- ivo://CDS.VizieR/J/A+A/434/1201
- Title:
- ESO VLTI Calibrators Program
- Short Name:
- J/A+A/434/1201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ESO Very Large Telescope Interferometer (VLTI) is one of the leading interferometric facilities. It is equiped with several 8.2 and 1.8m telescopes, a large number of baselines up to 200m, and with several subsystems designed to enable high quality measurements and to improve significantly the limits of sensitivities currently available to long-baseline interferometry. For this, a large number of observations of potential calibrators have been obtained during the commissioning phase of the VLTI. These data are publicly available.
- ID:
- ivo://CDS.VizieR/J/ApJ/895/140
- Title:
- EvryFlare. II. Parameters of 122 cool flare stars
- Short Name:
- J/ApJ/895/140
- Date:
- 15 Mar 2022 07:38:49
- Publisher:
- CDS
- Description:
- We measure rotation periods and sinusoidal amplitudes in Evryscope light curves for 122 two-minute K5-M4 TESS targets selected for strong flaring. The Evryscope array of telescopes has observed all bright nearby stars in the south, producing 2-minute cadence light curves since 2016. Long-term, high-cadence observations of rotating flare stars probe the complex relationship between stellar rotation, starspots, and superflares. We detect periods from 0.3487 to 104days and observe amplitudes from 0.008 to 0.216 g'mag. We find that the Evryscope amplitudes are larger than those in TESS with the effect correlated to stellar mass (p-value=0.01). We compute the Rossby number (Ro) and find that our sample selected for flaring has twice as many intermediate rotators (0.04<Ro<0.4) as fast (Ro<0.04) or slow (Ro>0.44) rotators; this may be astrophysical or a result of period detection sensitivity. We discover 30 fast, 59 intermediate, and 33 slow rotators. We measure a median starspot coverage of 13% of the stellar hemisphere and constrain the minimum magnetic field strength consistent with our flare energies and spot coverage to be 500G, with later-type stars exhibiting lower values than earlier-type stars. We observe a possible change in superflare rates at intermediate periods. However, we do not conclusively confirm the increased activity of intermediate rotators seen in previous studies. We split all rotators at Ro~0.2 into bins of PRot<10days and PRot>10 days to confirm that short-period rotators exhibit higher superflare rates, larger flare energies, and higher starspot coverage than do long-period rotators, at p-values of 3.2x10^-5^, 1.0x10^-5^, and 0.01, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A94
- Title:
- Exoplanetary parameters for 18 bright stars
- Short Name:
- J/A+A/586/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the interferometric angular diameters of 18 bright stars: HD3651 , HD9826, HD19994, HD75732, HD167042, HD170693, HD173416, HD185395, HD190360, HD217014, HD221345, HD1367, HD1671, HD154633, HD161178, HD161151, HD209369, HD218560. The first 11 host exoplanets (except HD185395). We combined these angular diameters {theta}_LD_ with the stellar distances to estimate the stellar radii. We perform SED fitting of the photometry to derive the stars bolometric flux Fbol with and without stellar extinction Av. We then give the effective temperature Teff_SED_ and angular diameter {theta}_SED_ from this SED fit, considering fixed Av, metallicity [Fe/H] and gravity log(g). Then, taking into account the stellar extinction, we derived from the bolometric flux and the measured angular diameters the effective temperature and luminosity to place the stars on the H-R diagram. We then used the PARSEC models to derive the best fit ages and masses of the stars, with error bars derived from Monte Carlo calculations. Typically, for main sequence stars, two distinct sets of solutions appear (an old and a young age). For stars that host known exoplanets, we also derive the exoplanets parameters considering the two different solutions (old and young): semi-major axis, planetary minimum mass and habitable zone of the host stars. Finally, we give the true mass, radius and density of the transiting exoplanet 55 Cnc e using the inteferometric radius and photometry.
- 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/ApJS/240/17
- Title:
- Exoplanets in the Antarctic sky. II. 116 candidates
- Short Name:
- J/ApJS/240/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report first results from the CHinese Exoplanet Searching Program from Antarctica (CHESPA)--a wide-field high-resolution photometric survey for transiting exoplanets carried out using telescopes of the AST3 (Antarctic Survey Telescopes times 3) project. There are now three telescopes (AST3-I, AST3-II, and CSTAR-II) operating at Dome A --the highest point on the Antarctic Plateau-- in a fully automatic and remote mode to exploit the superb observing conditions of the site, and its long and uninterrupted polar nights. The search for transiting exoplanets is one of the key projects for AST3. During the austral winters of 2016 and 2017 we used the AST3-II telescope to survey a set of target fields near the southern ecliptic pole, falling within the continuous viewing zone of the TESS mission. The first data release of the 2016 data, including images, catalogs, and light curves of 26578 bright stars (7.5<=m_i_<=15), was presented in Zhang+ (2018, J/ApJS/240/16). The best precision, as measured by the rms of the light curves at the optimum magnitude of the survey (m_i_=10), is around 2mmag. We detect 222 objects with plausible transit signals from these data, 116 of which are plausible transiting exoplanet candidates according to their stellar properties as given by the TESS Input Catalog, Gaia DR2, and TESS-HERMES spectroscopy. With the first data release from TESS expected in late 2018, this candidate list will be timely for improving the rejection of potential false-positives.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/38
- Title:
- Extended abundance analysis of KOIs
- Short Name:
- J/ApJS/237/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate stellar parameters and precise elemental abundances are vital pieces to correctly characterize discovered planetary systems, better understand planet formation, and trace galactic chemical evolution. We have performed a uniform spectroscopic analysis for 1127 stars, yielding accurate gravity, temperature, and projected rotational velocity in addition to precise abundances for 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y). Most of the stars in this sample are Kepler Objects of Interest, observed by the California-Kepler Survey, and include 1003 stars hosting 1562 confirmed planets. This catalog extends the uniform analysis of our previous catalog, bringing the total number of homogeneously analyzed stars to almost 2700 F, G, and K dwarfs. To ensure consistency between the catalogs, we performed an analysis of our ability to recover parameters as a function of signal-to-noise ratio (S/N) and present individual uncertainties as well as functions to calculate uncertainties for parameters derived from lower S/N spectra. With the updated parameters, we used isochrone fitting to derive new radii, masses, and ages for the stars. We use our abundance analysis to support the finding that the radius gap is likely a result of evolution rather than the result of primordial compositional differences between the two populations.
- ID:
- ivo://CDS.VizieR/J/ApJ/822/86
- Title:
- False positive probabilities for Q1-Q17 DR24 KOIs
- Short Name:
- J/ApJ/822/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present astrophysical false positive probability calculations for every Kepler Object of Interest (KOI) --the first large-scale demonstration of a fully automated transiting planet validation procedure. Out of 7056 KOIs, we determine that 1935 have probabilities vespa (Morton T.D. 2015ascl.soft03011M), a publicly available Python package that is able to be easily applied to any transiting exoplanet candidate.
