Basic physical parameters of a selected sample of evolved stars

By L. da Silva, L. Girardi, L. Pasquini, J. Setiawan, O. Lühe, J. D. Medeiros, A. Hatzes, M. Döllinger, A. Weiss. 2006

351 citations recorded by the source corpus.

We present the detailed spectroscopic analysis of 72 evolved stars, which were previously studied for accurate radial velocity variations. Using one Hyades giant and another well studied star as the reference abundance, we determine the [Fe/H] for the whole sample. These metallicities, together with the Teff values and the absolute V-band magnitude derived from Hipparcos parallaxes, are used to estimate basic stellar parameters (ages, masses, radii, (B−V)0 and log g) using theoretical isochrones and a Bayesian estimation method. The (B−V)0 values so estimated turn out to be in excellent agreement (to within ∼0.05 mag) with the observed (B−V), confirming the reliability of the Teff−(B−V)0 relation used in the isochrones. On the other hand, the estimated log g values are typically 0.2 dex lower than those derived from spectroscopy; this effect has a negligible impact on [Fe/H] determinations. The estimated diameters θ have been compared with limb darkening-corrected ones measured with independent methods, finding an agreement better than 0.3 mas within the 1 <θ< 10 mas interval (or, alternatively, finding mean differences of just 6%). We derive the age-metallicity relation for the solar neighborhood; for the first time to our knowledge, such a relation has been derived from observations of field giants rather than from open clusters and field dwarfs and subdwarfs. The age-metallicity relation is characterized by close-to-solar metallicities for stars younger than ∼4 Gyr, and by a large [Fe/H] spread with a trend towards lower metallicities for higher ages. In disagreement with other studies, we find that the [Fe/H] dispersion of young stars (less than 1 Gyr) is comparable to the observational errors, indicating that stars in the solar neighbourhood are formed from interstellar matter of quite homogeneous chemical composition. The three giants of our sample which have been proposed to host planets are not metal rich; this result is at odds with those for main sequence stars. However, two of these stars have masses much larger than a solar mass so we may be sampling a different stellar population from most radial velocity searches for extrasolar planets. We also confirm the previous indication that the radial velocity variability tends to increase along the RGB, and in particular with the stellar radius.

Subfields: Astronomy and Astrophysics, Education, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c67e48af858a371b911129a2b0c0032f6678a505

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Education

In Instrumentation

Citations in the corpus

Gaia FGK benchmark stars: Effective temperatures and surface gravities (2015, methodology): “…publications that apply more recent, 2MASS-based IRFM implementations (González Hernández & Bonifacio 2009; Casagrande et al. 2010) arrived at Teff 17 The third study (da Silva et al. 2006) with Teff closest to the fundamental value used the same method with an unspecified number of Fe I lines.”
FUNDAMENTAL PROPERTIES OF KEPLER PLANET-CANDIDATE HOST STARS USING ASTEROSEISMOLOGY (2013, neutral): “To derive masses and radii we have employed several different methods (da Silva et al. 2006; Stello et al. 2009; Basu et al. 2011; Miglio et al. 2013b; Silva Aguirre et al. 2013).”
Chemical similarities between Galactic bulge and local thick disk red giants: O, Na, Mg, Al, Si, Ca, and Ti (2010, methodology): “In addition, Yonsei-Yale (Y2; Demarque et al. 2004) and Padova isochrones (da Silva et al. 2006) were employed to determine evolutionary gravities, as well as the input massesthat were adopted for the trigonometric gravities.”
Vertical distribution of Galactic disk stars , IV. AMR and AVR from clump giants (2007, methodology): “For the present work, the largest contributions come from Mishenina et al. (2006) for 177 stars and da Silva et al. (2006) for 14 stars.”
Stellar Parameters and Elemental Abundances of Late-G Giants (2008, methodology): “…(1990) adopted the direct g-determination method [from L, Teff , and M (estimated from evolutionary tracks)], while the spectroscopic method based on Fe i and Fe ii lines (similar to that we used) was invoked by da Silva et al. (2006), Luck and Heiter (2007),8, and Hekker and Meléndez (2007).”
StarHorse : a Bayesian tool for determining stellar masses, ages, distances, and extinctions for field stars (2017, methodology): “In the same figure, we show the comparison between StarHorse and PARAM da Silva et al. (2006) ages (which incorporate results from asteroseismology using a method similar to StarHorse; upper right panel), and the comparison between StarHorse masses and those taken from asteroseismology scaling…”
EXTRACTING RADIAL VELOCITIES OF A- AND B-TYPE STARS FROM ECHELLE SPECTROGRAPH CALIBRATION SPECTRA (2015, methodology): “We estimated HR3067’s mass using the online Padova model interpolator9, which uses the technique of da Silva et al. (2006) to calculate masses based on photometry, parallaxes and spectroscopic parameters.”
Coudé-feed stellar spectral library – atmospheric parameters (2010, background): “We do not see the biases found by da Silva et al. (2006).”
FUNDAMENTAL PARAMETERS AND CHEMICAL COMPOSITION OF ARCTURUS (2011, methodology): “We did not take this approach but da Silva et al. (2006) provide an online tool to derive the stellar age, mass, and surface gravity using a Bayesian approach from any input observational data.6 We used this tool and found, for our derived parameters of Arcturus: τ = 8.4 ± 2.3Gyr, M = 1.00 ±…”
Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18 (2019, methodology): “Distances and extinctions were derived with the Bayesian stellar parameter estimation code A94, page 15 of 34 PARAM (da Silva et al. 2006; Rodrigues et al. 2014, 2017), using the global seismic oscillation parameters ∆ν and νmax as well as effective temperatures and metallicities determined from…”
Extrasolar planet population synthesis - IV. Correlations with disk metallicity, mass, and lifetime (2012, background): “While Setiawan et al. (2003) originally quoted a possible stellar mass of about 1 to 3 M , da Silva et al. (2006) more recently determined a mass of 0.94 ± 0.08M∗.”
The Second APOKASC Catalog: The Empirical Approach (2018, methodology): “Extinctions are derived using the direct method of stellar parameter estimation as implemented in the PARAM code (da Silva et al. 2006; Rodrigues et al. 2014).”
THE APOKASC CATALOG: AN ASTEROSEISMIC AND SPECTROSCOPIC JOINT SURVEY OF TARGETS IN THE KEPLER FIELDS (2014, background): “PARAM was run using a grid comprising models of the Padova group (Marigo et al. 2008), again including RC stars; further details may be found in Miglio et al. (2013).”
Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer (2017, methodology): “Stellar Mass and Age To estimate masses and ages for the evolved stars, we used the PARAM stellar model9 from Girardi et al. (2000) with a modified version of the method described in da Silva et al. (2006) and PARSEC isochrones from Bressan et al. (2012).”
The Solar Twin Planet Search. I. Fundamental parameters of the stellar sample (2014, background): “Isochrone age determinations are subject to a number of sampling biases whose impact can be minimized using Bayesian statistics (e.g., Pont & Eyer 2004; Jørgensen & Lindegren 2005; da Silva et al. 2006; Casagrande et al. 2011).”
CHARACTERIZING K2 PLANET DISCOVERIES: A SUPER-EARTH TRANSITING THE BRIGHT K DWARF HIP 116454 (2014, methodology): “We used the online Padova model interpolator32, which uses the technique of da Silva et al. (2006) to interpolate a measured effective temperature, metallicity, V –band magnitude, and 32 http://stev.oapd.inaf.it/cgi-bin/param parallax onto PARSEC isochrones, yielding estimates of stellar mass,…”
Chemical Similarities Between Galactic Bulge And Local Thick Disk Red Giant Stars (2008, methodology): “In addition, Yonsei-Yale (Demarque et al. 2004) and Padova isochrones (da Silva et al. 2006) were employed to determine evolutionary gravities.”
Precise radial velocities of giant stars. III. Spectroscopic stellar parameters (2007, methodology): “…directly, see for instance Valenti & Fischer (2005), or by imposing excitation and ionisation equilibrium for metal lines, using an LTE analysis and a grid of model atmospheres, see for instance Santos et al. (2004, 2005), da Silva et al. (2006), Takeda et al. (2002) and Luck & Heiter (2007).”