- ID:
- ivo://CDS.VizieR/J/AJ/136/2070
- Title:
- SEGUE stellar parameter pipeline. III.
- Short Name:
- J/AJ/136/2070
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report high-resolution spectroscopy of 125 field stars previously observed as part of the Sloan Digital Sky Survey and its program for Galactic studies, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These spectra are used to measure radial velocities and to derive atmospheric parameters, which we compare with those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS ugriz photometry and low-resolution (R~2000) spectroscopy.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/141/90
- Title:
- SEGUE stellar parameter pipeline. V.
- Short Name:
- J/AJ/141/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method for the determination of [{alpha}/Fe] ratios from low-resolution (R=2000) SDSS/SEGUE stellar spectra. By means of a star-by-star comparison with degraded spectra from the ELODIE spectral library and with a set of moderately high-resolution (R=15000) and medium-resolution (R=6000) spectra of SDSS/SEGUE stars, we demonstrate that we are able to measure [{alpha}/Fe] from SDSS/SEGUE spectra (with S/N>20/1) to a precision of better than 0.1dex, for stars with atmospheric parameters in the range Teff=[4500,7000]K, logg=[1.5,5.0], and [Fe/H]=[-1.4,+0.3], over the range [{alpha}/Fe]=[-0.1,+0.6]. For stars with [Fe/H]<-1.4, our method requires spectra with slightly higher signal-to-noise to achieve this precision (S/N>25/1).
- ID:
- ivo://CDS.VizieR/J/MNRAS/491/5489
- Title:
- Semi-detached double-lined eclipsing binaries
- Short Name:
- J/MNRAS/491/5489
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Semidetached eclipsing systems provide a unique opportunity to derive the basic properties of interacting binaries. The goal of this work is to collect and to make use of data on semidetached systems with available light and radial velocity curve solutions. I have compiled the most comprehensive list to date, of 119 semidetached double-lined eclipsing binaries, containing the orbital parameters and physical parameters of the components. I consider the classification of semidetached binaries and discuss gaps between various classes in the Hertzspung-Russell diagram. I list systems with component parameters that are inverted and briefly discuss their evolutionary state.
- ID:
- ivo://CDS.VizieR/J/ApJ/552/289
- Title:
- Semiregular variable stars in Baade's windows
- Short Name:
- J/ApJ/552/289
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By cross-correlating the results of two recent large-scale surveys, the general properties of a well-defined sample of semiregular variable stars have been determined. ISOGAL mid-infrared photometry (7 and 15{mu}m and MACHO V and R light curves are assembled for approximately 300 stars in the Baade's windows of low extinction toward the Galactic bulge. These stars are mainly giants of late M spectral type, evolving along the asymptotic giant branch (AGB). They are found to possess a wide and continuous distribution of pulsation periods and to obey an approximate logP-M_bol_ relation or set of such relations.
- ID:
- ivo://CDS.VizieR/J/A+A/651/A70
- Title:
- SHINE sample definition
- Short Name:
- J/A+A/651/A70
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Large surveys with new-generation high-contrast imaging instruments are needed to derive the frequency and properties of exoplanet populations with separations from 5 to 300au. A careful assessment of the stellar properties is crucial for a proper understanding of when, where, and how frequently planets form, and how they evolve. The sensitivity of detection limits to stellar age makes this a key parameter for direct imaging surveys. We describe the SpHere INfrared survey for Exoplanets (SHINE), the largest direct imaging planet-search campaign initiated at the VLT in 2015 in the context of the SPHERE Guaranteed Time Observations of the SPHERE consortium. In this rst paper we present the selection and the properties of the complete sample of stars surveyed with SHINE, focusing on the targets observed during the rst phase of the survey (from February 2015 to February 2017). This early sample composed of 150 stars is used to perform a preliminary statistical analysis of the SHINE data, deferred to two companion papers presenting the survey performance, main discoveries, and the preliminary statistical constraints set by SHINE. We describe the SpHere INfrared survey for Exoplanets (SHINE), the largest direct imaging planet-search campaign initiated at the VLT in 2015 in the context of the SPHERE Guaranteed Time Observations of the SPHERE consortium. In this rst paper we present the selection and the properties of the complete sample of stars surveyed with SHINE, focusing on the targets observed during the first phase of the survey (from February 2015 to February 2017). This early sample composed of 150 stars is used to perform a preliminary statistical analysis of the SHINE data, deferred to two companion papers presenting the survey performance, main discoveries, and the preliminary statistical constraints set by SHINE. Based on a large database collecting the stellar properties of all young nearby stars in the solar vicinity (including kinematics, membership to moving groups, isochrones, lithium abundance, rotation, and activity), we selected the original sample of 800 stars that were ranked in order of priority according to their sensitivity for planet detection in direct imaging with SPHERE. The properties of the stars that are part of the early statistical sample were revisited, including for instance measurements from the GAIA Data Release 2. Rotation periods were derived for the vast majority of the late-type objects exploiting TESS light curves and dedicated photometric observations. The properties of individual targets and of the sample as a whole are presented.
- ID:
- ivo://CDS.VizieR/J/AJ/158/68
- Title:
- Short-period variables in young open cluster Stock 8
- Short Name:
- J/AJ/158/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-series photometry in the field of Stock 8 and identified 130 short-period variable stars. Twenty-eight main-sequence and 23 pre-main-sequence variables are found to be part of cluster Stock 8. The main-sequence variables are classified as slow pulsators of the B-type, {beta} Cep, and {delta} Scuti stars. Fourteen main-sequence stars could be new class variables as discussed by Mowlavi et al. (2013, J/A+A/554/A108) and Lata et al. (2011MNRAS.418.1346L; 2012MNRAS.427.1449L; 2014, J/MNRAS/442/273; 2016MNRAS.456.2505L). The age and mass of pre-main-sequence variables are found to be ~<5 Myr and in the mass range of 0.5-2.8 M_{sun}_, respectively. These pre-main-sequence stars could be T-Tauri variables. We have found 5 and 2 of 23 pre-main-sequence variables as classical T-Tauri stars and Herbig Ae/Be stars, respectively, whereas 16 pre-main-sequence stars are classified as weak-line T-Tauri stars.
- ID:
- ivo://CDS.VizieR/J/AJ/156/277
- Title:
- Sixty validated planets from K2 campaigns 5-8
- Short Name:
- J/AJ/156/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a uniform analysis of 155 candidates from the second year of NASA's K2 mission (Campaigns 5-8), yielding 60 statistically validated planets spanning a range of properties with median values of R_p_=2.5 R_{Earth}_, P=7.1 days, T_eq_=811 K, and J=11.3 mag. The sample includes 24 planets in 11 multiplanetary systems, as well as 18 false positives and 77 remaining planet candidates. Of particular interest are 18 planets smaller than 2 R_{Earth}_, five orbiting stars brighter than J=10 mag, and a system of four small planets orbiting the solar-type star EPIC 212157262. We compute planetary transit parameters and false-positive probabilities using a robust statistical framework and present a complete analysis incorporating the results of an intensive campaign of high-resolution imaging and spectroscopic observations. This work brings the K2 yield to over 360 planets, and by extrapolation, we expect that K2 will have discovered ~600 planets before the expected depletion of its onboard fuel in late 2018.
- ID:
- ivo://CDS.VizieR/J/AJ/162/192
- Title:
- SOAR TESS survey. II. Impact of stellar companions
- Short Name:
- J/AJ/162/192
- Date:
- 14 Mar 2022 06:53:02
- Publisher:
- CDS
- Description:
- We present the results of the second year of exoplanet candidate host speckle observations from the SOAR TESS survey. We find 89 of the 589 newly observed TESS planet candidate hosts have companions within 3", resulting in light-curve dilution, that, if not accounted for, leads to underestimated planetary radii. We combined these observations with those from PaperI to search for evidence of the impact binary stars have on planetary systems. Removing the one-quarter of the targets observed identified as false-positive planet detections, we find that transiting planets are suppressed by nearly a factor of seven in close solar-type binaries, nearly twice the suppression previously reported. The result on planet occurrence rates that are based on magnitude-limited surveys is an overestimation by a factor of two if binary suppression is not taken into account. We also find tentative evidence for similar close binary suppression of planets in M-dwarf systems. Last, we find that the high rates of widely separated companions to hot Jupiter hosts previously reported was likely a result of false-positive contamination in our sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/790/L23
- Title:
- Solar analogs and twins rotation by Kepler
- Short Name:
- J/ApJ/790/L23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new sample of solar analogs and twin candidates has been constructed and studied, paying particular attention to their light curves from NASA's Kepler mission. This Letter aims to assess their evolutionary status, derive their rotation and ages, and identify those which are solar analogs or solar twin candidates. We separate out the subgiants that compose a large fraction of the asteroseismic sample, and which show an increase in the average rotation period as the stars ascend the subgiant branch. The rotation periods of the dwarfs, ranging from 6 to 30 days and averaging 19 days, allow us to assess their individual evolutionary states on the main sequence and to derive their ages using gyrochronology. These ages are found to be in agreement with a correlation coefficient of r = 0.79 with independent asteroseismic ages, where available. As a result of this investigation, we are able to identify 34 stars as solar analogs and 22 of them as solar twin candidates.
- ID:
- ivo://CDS.VizieR/J/AJ/147/94
- Title:
- Solar neighborhood. XXXII. L and M dwarfs
- Short Name:
- J/AJ/147/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a Hertzsprung-Russell diagram for the stellar/substellar boundary based on a sample of 63 objects ranging in spectral type from M6V to L4. We report newly observed VRI photometry for all 63 objects and new trigonometric parallaxes for 37 objects. The remaining 26 objects have trigonometric parallaxes from the literature. We combine our optical photometry and trigonometric parallaxes with 2MASS and WISE photometry and employ a novel spectral energy distribution fitting algorithm to determine effective temperatures, bolometric luminosities, and radii. Our uncertainties range from ~20K to ~150K in temperature, ~0.01 to ~0.06 in log (L/L_{sun}_) and ~3% to ~10% in radius. We check our methodology by comparing our calculated radii to radii directly measured via long baseline optical interferometry. We find evidence for the local minimum in the radius-temperature and radius-luminosity trends that signals the end of the stellar main sequence and the start of the brown dwarf sequence at T_eff_~2075K, log(L/L_{sun}_)~-3.9, and (R/R_{sun}_)~0.086. The existence of this local minimum is predicted by evolutionary models, but at temperatures ~400K cooler. The minimum radius happens near the locus of 2MASS J0523-1403, an L2.5 dwarf with V-K=9.42. We make qualitative arguments as to why the effects of the recent revision in solar abundances accounts for the discrepancy between our findings and the evolutionary models. We also report new color-absolute magnitude relations for optical and infrared colors which are useful for estimating photometric distances. We study the optical variability of all 63 targets and find an overall variability fraction of 36_-7_^+9^% at a threshold of 15mmag in the I band, which is in agreement with previous studies.
