- ID:
- ivo://CDS.VizieR/J/ApJ/831/L6
- Title:
- Eclipsing binary parallaxes with Gaia data
- Short Name:
- J/ApJ/831/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We test the parallaxes reported in the Gaia first data release using the sample of eclipsing binaries with accurate, empirical distances from Stassun & Torres (2016, arXiv:1609.02579). We find an average offset of -0.25+/-0.05mas in the sense of the Gaia parallaxes being too small (i.e., the distances too long). The offset does not depend strongly on obvious parameters such as color or brightness. However, we find with high confidence that the offset may depend on ecliptic latitude: the mean offset is -0.38+/-0.06mas in the ecliptic north and -0.05+/-0.09mas in the ecliptic south. The ecliptic latitude dependence may also be represented by the linear relation, {Delta}{pi}~-0.22(+/-0.05)-0.003(+/-0.001)x{beta}mas ({beta} in degrees). Finally, there is a possible dependence of the parallax offset on distance, with the offset becoming negligible for {pi}<~1mas; we discuss whether this could be caused by a systematic error in the eclipsing binary distance scale, and reject this interpretation as unlikely.
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- ID:
- ivo://CDS.VizieR/J/A+A/411/559
- Title:
- Effective temperature for 181 F-K dwarfs
- Short Name:
- J/A+A/411/559
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Line depth ratios measured on high resolution (R=42000), high S/N echelle spectra are used for the determination of precise effective temperatures of 181 F, G, K main Sequence stars with about solar metallicity (-0.5<[Fe/H]<+0.5). A set of 105 relations is obtained which rely Teff on ratios of the strengths of lines with high and low excitation potentials, calibrated against previously published precise (1%) temperature estimates. The application range of the calibrations is 4000-6150K (F8V-K7V). The internal error of a single calibration is less than 100K, while the combination of all calibrations for a spectrum of S/N=100 reduces uncertainty to only 5-10K, and for S/N=200 or higher to better than 5K. The zero point of the temperature scale is directly defined from reflection spectra of the Sun with an uncertainty about 1K. The application of this method to investigation of the planet host stars properties is discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/444/941
- Title:
- Effective temperature of B stars
- Short Name:
- J/A+A/444/941
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We establish an empirical effective temperature calibration of main sequence, luminosity class V to III B-type stars for the Delta a photometric system which was originally developed to detect magnetic chemically peculiar objects of the upper main sequence (early B-type to early F-type) at 5200A. However, this system provides the index g1-y which shows an excellent correlation with B-V as well as b-y and can be used as an indicator of the effective temperature. This is supplemented by a very accurate color-magnitude diagram, y or V versus g1-y, which can be used, for example, to determine the reddening, distance and age of an open cluster. This makes the Delta a photometric system an excellent tool to investigate the HR diagram in more detail. Using the reddening-free parameters and already established calibrations within the Stromgren uvbybeta, Geneva 7-color and Johnson UBV systems, a polynomial fit of third degree for the averaged effective temperatures to the individual (g1-y)0 values was derived. For this purpose, data from the literature as well as new observations were taken resulting in 225 suitable bright normal B-type objects. The statistical mean of the error for this sample is 238K which is sufficient to investigate the HRD of distant galactic open clusters as well as extragalactic aggregates in the future.
- ID:
- ivo://CDS.VizieR/J/A+A/443/851
- Title:
- Effective temperature of 30 Dor population
- Short Name:
- J/A+A/443/851
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The star-formation history and IMF of the field population of the 30 Doradus super-association is determined using Wide Field Imager photometry. The cluster NGC 2070 and the OB association LH104 are also studied and used for comparison. The star-formation history of the 30~Doradus super-association appears to be characterized by a large increase in star-formation activity 10Myr to 20Myr ago. This seems to be the case across the whole eastern half of the LMC as demonstrated by the ages of stellar populations as far away as 30 Doradus and Shapley's Constellation III. Star-formation appears to be occurring at a constant rate in the field and in loose associations, and in bursts in the clusters. The field IMF is found to have almost the exact Salpeter slope in the range 7M_{sun}_<=M<=40M_{sun}_, at odds with previous claims. We find that, for objects with more complex star-formation histories, Be stars and selective incompleteness strongly affect the determination of the IMF for M>40M_{sun}_, naturally explaining the observed deviation of the high mass IMF slope from the Salpeter value.The present work supports the idea of a universal IMF.
- 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+AS/129/505
- Title:
- Effective temperatures by Infrared Flux Method
- Short Name:
- J/A+AS/129/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Effective temperatures for 420 stars with spectral types between A0 and K3, and luminosity classes between II and V, selected for a flux calibration of the Infrared Space Observatory, ISO, have been determined using the Infrared Flux Method (IRFM). The determinations are based on narrow and wide band photometric data obtained for this purpose, and take into account previously published narrow-band measures of temperature.
- ID:
- ivo://CDS.VizieR/J/ApJS/199/30
- Title:
- Effective temperature scale for KIC stars
- Short Name:
- J/ApJS/199/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of revised effective temperatures for stars observed in long-cadence mode in the Kepler Input Catalog (KIC). We use Sloan Digital Sky Survey (SDSS) griz filters tied to the fundamental temperature scale. Polynomials for griz color-temperature relations are presented, along with correction terms for surface gravity effects, metallicity, and statistical corrections for binary companions or blending. We compare our temperature scale to the published infrared flux method (IRFM) scale for V_T_JKs in both open clusters and the Kepler fields. We find good agreement overall, with some deviations between (J-Ks)-based temperatures from the IRFM and both SDSS filter and other diagnostic IRFM color-temperature relationships above 6000K. For field dwarfs, we find a mean shift toward hotter temperatures relative to the KIC, of order 215K, in the regime where the IRFM scale is well defined (4000K to 6500K). This change is of comparable magnitude in both color systems and in spectroscopy for stars with T_eff_ below 6000K. Systematic differences between temperature estimators appear for hotter stars, and we define corrections to put the SDSS temperatures on the IRFM scale for them. When the theoretical dependence on gravity is accounted for, we find a similar temperature scale offset between the fundamental and KIC scales for giants. We demonstrate that statistical corrections to color-based temperatures from binaries are significant. Typical errors, mostly from uncertainties in extinction, are of order 100K.
- ID:
- ivo://CDS.VizieR/J/ApJ/626/446
- Title:
- Effective temperature scale of FGK stars
- Short Name:
- J/ApJ/626/446
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The infrared flux method (IRFM) has been applied to a sample of 135 dwarf and 36 giant stars covering the following regions of the atmospheric parameter space: (1) the metal-rich ([Fe/H]>~0) end (consisting mostly of planet-hosting stars), (2) the cool (Teff<~5000K) metal-poor (-1<~[Fe/H]<~-3) dwarf region, and (3) the very metal-poor ([Fe/H]<~-2.5) end.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A15
- Title:
- Effective temperature scale of M dwarfs
- Short Name:
- J/A+A/556/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Despite their large number in the Galaxy, M dwarfs remain elusive objects and the modeling of their photosphere has long remained a challenge (molecular opacities, dust cloud formation). Our objectives are to validate the BT-Settl model atmospheres, update the M dwarf T_eff_-spectral type relation, and find the atmospheric parameters of the stars in our sample. We compare two samples of optical spectra covering the whole M dwarf sequence with the most recent BT-Settl synthetic spectra and use a {chi}^2^ minimization technique to determine Teff. The first sample consists of 97 low-resolution spectra obtained with New Technology Telescope (NTT) at La Silla Observatory. The second sample contains 55 medium-resolution spectra obtained at the Siding Spring Observatory (SSO). The spectral typing is realized by comparison with already classified M dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+AS/130/215
- Title:
- Effective temperatures of Ap stars
- Short Name:
- J/A+AS/130/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new method of determination of the effective temperatures of Ap stars is proposed. The method is based on the fact that the slopes of the energy distribution in the Balmer continuum near the Balmer jump for "normal" main sequence stars and Ap stars with the same effective temperature are identical. The effective temperature calibration is based on a sample of main sequence stars with well known temperatures (Sokolov, 1995, Cat. <J/A+AS/110/553>).
