- ID:
- ivo://CDS.VizieR/J/AJ/155/165
- Title:
- Dissipation in exoplanet hosts from tidal spin-up
- Short Name:
- J/AJ/155/165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stars with hot Jupiters (HJs) tend to rotate faster than other stars of the same age and mass. This trend has been attributed to tidal interactions between the star and planet. A constraint on the dissipation parameter Q_*_' follows from the assumption that tides have managed to spin up the star to the observed rate within the age of the system. This technique was applied previously to HATS-18 and WASP-19. Here, we analyze the sample of all 188 known HJs with an orbital period <3.5 days and a "cool" host star (T_eff_<6100 K). We find evidence that the tidal dissipation parameter (Q_*_') increases sharply with forcing frequency, from 10^5^ at 0.5 day^-1^ to 10^7^ at 2 day^-1^. This helps to resolve a number of apparent discrepancies between studies of tidal dissipation in binary stars, HJs, and warm Jupiters. It may also allow for a HJ to damp the obliquity of its host star prior to being destroyed by tidal decay.
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- ID:
- ivo://CDS.VizieR/J/A+A/640/A2
- Title:
- Dwarfs & giants surface brightness-colour relations
- Short Name:
- J/A+A/640/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Surface brightness-colour relations (SBCRs) are used to derive the stellar angular diameters from photometric observations. They have various astrophysical applications, such as the distance determination of eclipsing binaries or the determination of exoplanet parameters. However, strong discrepancies between the SBCRs still exist in the literature, in particular for early and late-type stars. We aim at calibrating new SBCRs as a function of the spectral type and the luminosity class of the stars. Our purpose is also to apply homogeneous criteria for the selection of the reference stars and on the basis of an exhaustive and up-to-date list of interferometric late-type targets. We implement criteria to select measurements in the JMMC Measured Diameters Catalog (JMDC). We then apply additional criteria on the photometric measurements used to build the SBCRs, together with stellar characteristics diagnostics. We build SBCRs for F5/K7-II/III, F5/K7-IV/V, M-II/III and M-V stars, with respective RMS of {sigma}_FV_=0.0022mag, {sigma}_FV_ =0.0044mag, {sigma}_FV_=0.0046mag, and {sigma}_FV_=0.0038mag. This results in a precision on the angular diameter of 1.0%, 2.0%, 2.1% and 1.7%, respectively. These relations cover a large V-K colour range of magnitude, from 1 to 7.5. Our work demonstrates that SBCRs are significantly dependent on the spectral type and the luminosity class of the star. Through a new set of interferometric measurements, we demonstrate the critical importance of the selection criteria proposed for the calibration of SBCR. Finally, using the Gaia photometry for our samples, we obtain (G-K) SBCRs with a precision on the angular diameter between 1.1% and 2.4%. By adopting a refined and homogeneous methodology we show that the spectral type and the class of the star should be considered when applying a SBCR. This is particularly important in the context of PLATO.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/61
- Title:
- Early-type EBs with intermediate orbital periods
- Short Name:
- J/ApJ/810/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze 221 eclipsing binaries (EBs) in the Large Magellanic Cloud with B-type main-sequence (MS) primaries (M_1_~4-14 M_{sun}_) and orbital periods P=20-50 days that were photometrically monitored by the Optical Gravitational Lensing Experiment. We utilize our three-stage automated pipeline to (1) classify all 221 EBs, (2) fit physical models to the light curves of 130 detached well-defined EBs from which unique parameters can be determined, and (3) recover the intrinsic binary statistics by correcting for selection effects. We uncover two statistically significant trends with age. First, younger EBs tend to reside in dustier environments with larger photometric extinctions, an empirical relation that can be implemented when modeling stellar populations. Second, younger EBs generally have large eccentricities. This demonstrates that massive binaries at moderate orbital periods are born with a Maxwellian "thermal" orbital velocity distribution, which indicates they formed via dynamical interactions. In addition, the age-eccentricity anticorrelation provides a direct constraint for tidal evolution in highly eccentric binaries containing hot MS stars with radiative envelopes. The intrinsic fraction of B-type MS stars with stellar companions q=M_2_/M_1_>0.2 and orbital periods P=20-50 days is (7+/-2)%. We find early-type binaries at P=20-50 days are weighted significantly toward small mass ratios q~0.2-0.3, which is different than the results from previous observations of closer binaries with P<20 days. This indicates that early-type binaries at slightly wider orbital separations have experienced substantially less competitive accretion and coevolution during their formation in the circumbinary disk.
- ID:
- ivo://CDS.VizieR/J/AJ/159/189
- Title:
- Eclipse timings for 9 contact binaries
- Short Name:
- J/AJ/159/189
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the first light curve synthesis and orbital period change analysis of nine contact binaries around the short-period limit. It is found that all these systems are W-subtype contact binaries. One of them is a medium contact system while the others are shallow contact ones. Four of them manifest obvious O'Connell effect explained by a dark spot or hot spot on one of the component stars. Third light was detected in three systems. By investigating orbital period variations, we found that four of the targets display a secular period decrease while the others exhibit a long-term period increase. The secular period decrease is more likely caused by angular-momentum loss while the long-term period increase is due to mass transfer from the less massive component to the more massive one. Based on the statistic of 19 ultrashort-period contact binaries with known orbital period changes, we found that seven of them display long-term decrease (three of them also exhibit cyclic variations), ten of them manifest long-term increase while two of them only show cyclic variation, and that most of them are shallow contact binaries supporting the long timescale angular-momentum loss theory suggested by Stepien. For the three deep contact systems, we found that they are probably triple systems. The tertiary companion plays an essential role during their formation and evolution.
- ID:
- ivo://CDS.VizieR/J/MNRAS/378/179
- Title:
- Eclipsing Binary with Eccentric Orbits Catalog
- Short Name:
- J/MNRAS/378/179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new catalog of eclipsing binary stars with eccentric orbits is presented. The catalog lists the physical parameters (including apsidal motion parameters) of 124 eclipsing binaries with eccentric orbits. In addition, the catalog also contains a list of 150 candidate systems, about which fewer details are known at present.
- ID:
- ivo://CDS.VizieR/J/A+A/450/735
- Title:
- Effective temperatures and radii of stars
- Short Name:
- J/A+A/450/735
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents a method to determine effective temperatures, angular semi-diameters and bolometric corrections for population I and II FGK type stars based on V and 2MASS IR photometry. Accurate calibration is accomplished by using a sample of solar analogues, whose average temperature is assumed to be equal to the solar effective temperature of 5777K.
- 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.
