- ID:
- ivo://CDS.VizieR/J/AN/328/938
- Title:
- Teff/line-depth ratio for ELODIE spectra
- Short Name:
- J/AN/328/938
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The dependence on the temperature of photospheric line-depth ratios (LDRs) in the spectral range 619.0-628.0nm is investigated by using a sample of 174 ELODIE Archive stellar spectra of luminosity class from V to III. The rotational broadening effect on LDRs is also studied. We provide useful calibrations of effective temperature versus LDRs for giant and main sequence stars with 3800<~T_eff_<~6000K and vsini in the range 0-30km/s. We found that, with the exception of very few line pairs, LDRs, measured at a spectral resolution as high as 42000, depend on vsini and that, by neglecting the rotational broadening effect, the T_eff_ determination can be wrong by ~100K in the worst cases.
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- ID:
- ivo://CDS.VizieR/J/ApJ/851/26
- Title:
- Teff, metallicity and Ti abundance of M dwarfs
- Short Name:
- J/ApJ/851/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ability to perform detailed chemical analysis of Sun-like F-, G-, and K-type stars is a powerful tool with many applications, including studying the chemical evolution of the Galaxy and constraining planet formation theories. Unfortunately, complications in modeling cooler stellar atmospheres hinders similar analyses of M dwarf stars. Empirically calibrated methods to measure M dwarf metallicity from moderate-resolution spectra are currently limited to measuring overall metallicity and rely on astrophysical abundance correlations in stellar populations. We present a new, empirical calibration of synthetic M dwarf spectra that can be used to infer effective temperature, Fe abundance, and Ti abundance. We obtained high-resolution (R~25000), Y-band (~1{mu}m) spectra of 29 M dwarfs with NIRSPEC on Keck II. Using the PHOENIX stellar atmosphere modeling code (version 15.5), we generated a grid of synthetic spectra covering a range of temperatures, metallicities, and alpha-enhancements. From our observed and synthetic spectra, we measured the equivalent widths of multiple Fe I and Ti I lines and a temperature-sensitive index based on the FeH band head. We used abundances measured from widely separated solar-type companions to empirically calibrate transformations to the observed indices and equivalent widths that force agreement with the models. Our calibration achieves precisions in Teff, [Fe/H], and [Ti/Fe] of 60K, 0.1dex, and 0.05dex, respectively, and is calibrated for 3200K<Teff<4100K, -0.7<[Fe/H]<+0.3, and -0.05<[Ti/Fe]<+0.3. This work is a step toward detailed chemical analysis of M dwarfs at a precision similar to what has been achieved for FGK stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/800/85
- Title:
- Teff, radii and luminosities of cool dwarfs
- Short Name:
- J/ApJ/800/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interferometric radius measurements provide a direct probe of the fundamental parameters of M dwarfs. However, interferometry is within reach for only a limited sample of nearby, bright stars. We use interferometrically measured radii, bolometric luminosities, and effective temperatures to develop new empirical calibrations based on low-resolution, near-infrared spectra. We find that H-band Mg and Al spectral features are good tracers of stellar properties, and derive functions that relate effective temperature, radius, and log luminosity to these features. The standard deviations in the residuals of our best fits are, respectively, 73K, 0.027R_{sun}_, and 0.049dex (an 11% error on luminosity). Our calibrations are valid from mid K to mid M dwarf stars, roughly corresponding to temperatures between 3100 and 4800K. We apply our H-band relationships to M dwarfs targeted by the MEarth transiting planet survey and to the cool Kepler Objects of Interest (KOIs). We present spectral measurements and estimated stellar parameters for these stars. Parallaxes are also available for many of the MEarth targets, allowing us to independently validate our calibrations by demonstrating a clear relationship between our inferred parameters and the stars' absolute K magnitudes. We identify objects with magnitudes that are too bright for their inferred luminosities as candidate multiple systems. We also use our estimated luminosities to address the applicability of near-infrared metallicity calibrations to mid and late M dwarfs. The temperatures we infer for the KOIs agree remarkably well with those from the literature; however, our stellar radii are systematically larger than those presented in previous works that derive radii from model isochrones. This results in a mean planet radius that is 15% larger than one would infer using the stellar properties from recent catalogs. Our results confirm the derived parameters from previous in-depth studies of KOIs 961 (Kepler-42), 254 (Kepler-45), and 571 (Kepler-186), the latter of which hosts a rocky planet orbiting in its star's habitable zone.
- ID:
- ivo://CDS.VizieR/J/A+A/458/293
- Title:
- Temperature calibration for A & mid F-type stars
- Short Name:
- J/A+A/458/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the {Delta}a photometric system, it is possible to study very distant galactic and even extragalactic clusters with a high level of accuracy. The new calibration presented is a powerful extension. Because no a-priori reddening-free photometric parameters are available for the investigated spectral range, we have applied the dereddening calibrations of the Stromgren uvby{beta} system and compared them with extinction models for the Milky Way. We derived an empirical temperature calibration for the {Delta}a photometric system for A-type to mid F-type with a mean of the error for the whole sample of {Delta}T(eff) is 134K which is lower than the value in Paper I (Paunzen et al., 2005, Cat. <J/A+A/444/941>) for hotter stars. No statistically significant effect of the rotational velocity on the precision of the calibration was found.
- ID:
- ivo://CDS.VizieR/J/A+A/398/721
- Title:
- Temperature catalog of class IV-V stars
- Short Name:
- J/A+A/398/721
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains values of theta [= 5040/T_eff_] for 951 F-K stars which are on or near the main sequence. Values of Cousins R-I are also given for most stars.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A33
- Title:
- Temperature evolution in massive clumps
- Short Name:
- J/A+A/603/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observational identification of a solid evolutionary sequence for high-mass star-forming regions is still missing. Spectroscopic observations give the opportunity to test possible schemes and connect the phases identified to physical processes. We aim to use the progressive heating of the gas caused by the feedback of high-mass young stellar objects to prove the statistical validity of the most common schemes used to observationally define an evolutionary sequence for high-mass clumps, and characterise the sensitivity of different tracers to this process. From the spectroscopic follow-ups carried out towards submillimeter continuum (dust) emission-selected massive clumps (the ATLASGAL TOP100 sample) with the IRAM 30m, Mopra, and APEX telescopes between 84GHz and 365GHz, we selected several multiplets of CH_3_N, CH_3_CH, and CH_3_H emission lines to derive and compare the physical properties of the gas in the clumps along the evolutionary sequence, fitting simultaneously the large number of lines that these molecules have in the observed band. Our findings are compared with results obtained from optically thin CO isotopologues, dust, and ammonia from previous studies on the same sample. The chemical properties of each species have a major role on the measured physical properties. Low temperatures are traced by ammonia, methanol, and CO (in the early phases), the warm and dense envelope can be probed with CH_3_N, CH_3_CH, and, in evolved sources where CO is abundant in the gas phase, via its optically thin isotopologues. CH_3_H and CH_3_N are also abundant in the hot cores, and we suggest that their high-excitation transitions are good tools to study the kinematics in the hot gas associated with the inner envelope surrounding the young stellar objects that these clumps are hosting. All tracers show, to different degrees according to their properties, progressive warming with evolution. The relation between gas temperature and the luminosity-to-mass (L/M) ratio is reproduced by a simple toy model of a spherical, internally heated clump.
- ID:
- ivo://CDS.VizieR/J/ApJS/159/100
- Title:
- Temperatures and Rc photometry in the Hyades
- Short Name:
- J/ApJS/159/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Hyades photometry published by Mendoza (1967BOTT....4..149M) and other authors, Pinsonneault et al. (2004ApJ...600..946P) have recently concluded that Cousins V-I photometry published by Taylor & Joner (1985AJ.....90..479T, 1988AJ.....96..211T, 1996AJ....111.1338T) is not on the Cousins system. Extensive tests of the Taylor-Joner photometry and other pertinent results are therefore performed in this paper. It is found that in part, the Pinsonneault et al. conclusion rests on (1) a systematic error in Mendoza's (R-I)J photometry and (2) a small error in an approximate Johnson-to-Cousins transformation published by Bessell. For the Taylor-Joner values of (V-R)C, it is found that there are possible (though not definite) differences of several mmag with other results. However, the Taylor-Joner values of (R-I)C data are supported at the 1mmag level. Using the (R-I)C data and other published results, an (R-I)C catalog is assembled for 146 Hyades stars with spectral types earlier than about K5. For single stars with multiple contributing data, the rms errors of the catalog entries are less than 4.4 mmag. Temperatures on the Di Benedetto angular-diameter scale are also given in the catalog and are used to help update published analyses of high-dispersion values of [Fe/H] for the Hyades. The best current mean Hyades value of [Fe/H] is found to be +0.103+/-0.008dex and is essentially unchanged from its previous value. In addition to these numerical results, recommendations are made about improving attitudes and practices that are pertinent to issues like those raised by Pinsonneault et al.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/3473
- Title:
- Temperatures of Kepler eclipsing binaries
- Short Name:
- J/MNRAS/437/3473
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have combined the Kepler Eclipsing Binary Catalogue with information from the HES (Everett et al., 2012PASP..124..316E), KIS (Greiss et al, 2012AJ....144...24G, Cat. J/AJ/144/24) and 2MASS (Cat. II/246) photometric surveys to produce spectral energy distribution fits to over 2600 eclipsing binaries in the catalogue over a wavelength range of 0.36-2.16{AA}. We present primary (T1) and secondary (T2) stellar temperatures, plus information on the stellar radii and system distance ratios. The derived temperatures are on average accurate to 370K in T1 and 620K in T2. Our results improve on the similarly derived physical parameters of the Kepler Input Catalogue through consideration of both stars of the binary system rather than a single star model, and inclusion of additional U-band photometry. We expect these results to aid future uses of the Kepler eclipsing binary data, both in target selection and to inform users of the extremely high-precision light curves available. We do not include surface gravities or system metallicities, as these were found to have an insignificant effect on the observed photometric bands.
- ID:
- ivo://CDS.VizieR/J/ApJ/791/101
- Title:
- Terzan 5 chemical and kinematical properties
- Short Name:
- J/ApJ/791/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a study aimed at determining the kinematical and chemical properties of Terzan 5, we present the first characterization of the bulge stars surrounding this puzzling stellar system. We observed 615 targets located well beyond the tidal radius of Terzan 5 and found that their radial velocity distribution is well described by a Gaussian function peaked at <v_rad_> = +21.0+/-4.6 km/s with dispersion {sigma}_v_= 113.0+/-2.7 km/s. This is one of the few high-precision spectroscopic surveys of radial velocities for a large sample of bulge stars in such a low and positive latitude environment (b = +1.7{deg}). We found no evidence of the peak at <v_rad_> ~ +200 km/s found in Nidever et al. (2012ApJ...755L..25N). Strong contamination of many observed spectra by TiO bands prevented us from deriving the iron abundance for the entire spectroscopic sample, introducing a selection bias. The metallicity distribution was finally derived for a subsample of 112 stars in a magnitude range where the effect of the selection bias is negligible. The distribution is quite broad and roughly peaked at solar metallicity ([Fe/H] =~ +0.05 dex) with a similar number of stars in the super-solar and in the sub-solar ranges. The population number ratios in different metallicity ranges agree well with those observed in other low-latitude bulge fields, suggesting (1) the possible presence of a plateau for|b| < 4{deg} in the ratio between stars in the super-solar (0 < [Fe/H] <0.5 dex) and sub-solar (-0.5 < [Fe/H] <0 dex) metallicity ranges; (2) a severe drop in the metal-poor component ([Fe/H] <-0.5) as a function of Galactic latitude.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/2004
- Title:
- TESS-HERMES Survey Data Release 1 catalog
- Short Name:
- J/MNRAS/473/2004
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) will provide high-precision time series photometry for millions of stars with at least a half-hour cadence. Of particular interest are the circular regions of 12{deg} radius centred around the ecliptic poles that will be observed continuously for a full year. Spectroscopic stellar parameters are desirable to characterize and select suitable targets for TESS, whether they are focused on exploring exoplanets, stellar astrophysics or Galactic archaeology. Here, we present spectroscopic stellar parameters (Teff, logg, [Fe/H], vsini, vmicro) for about 16000 dwarf and subgiant stars in TESS' southern continuous viewing zone. For almost all the stars, we also present Bayesian estimates of stellar properties including distance, extinction, mass, radius and age using theoretical isochrones. Stellar surface gravity and radius are made available for an additional set of roughly 8500 red giants. All our target stars are in the range 10<V<13.1. Among them, we identify and list 227 stars belonging to the Large Magellanic Cloud. The data were taken using the High Efficiency and Resolution Multi-Element Spectrograph (HERMES; R~28000) at the Anglo-Australian Telescope as part of the TESS-HERMES survey. Comparing our results with the TESS Input Catalogue (TIC) shows that the TIC is generally efficient in separating dwarfs and giants, but it has flagged more than 100 cool dwarfs (Teff<4800K) as giants, which ought to be high-priority targets for the exoplanet search. The catalogue can be accessed via http://www.physics.usyd.edu.au/tess-hermes/, or at Mikulski Archive for Space Telescopes (MAST).
