Using non-solar-scaled opacities to derive stellar parameters.

C. SAFFE; M. FLORES; P. MIQUELARENA; F. M. LÓPEZ; M. JAQUE ARANCIBIA; A. COLLADO; E. JOFRÉ; R. PETRUCCI

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2018

0004-6361

We implemented non-solar-scaled opacities in a simultaneous derivationof fundamental parameters and abundances. We carried out ahigh-precision stellar parameters and abundance determination byapplying non-solar-scaled opacities and model atmospheres. Our sample iscomposed by 20 stars including main-sequence and evolved objects.Opacities for an arbitrary composition and vmicro were calculatedthrough the Opacity Sampling method. We obtained a small difference instellar parameters derived with non-solar-scaled opacities compared toclassical solar-scaled models. The differences in Teff, log g and [Fe/H]amount up to 26 K, 0.05 dex and 0.020 dex for the stars in our sample.These differences could be considered as the first estimation of theerror due to the use of classical solar-scaled opacities to derivestellar parameters with solar-type and evolved stars. Some chemicalspecies could also show an individual variation higher than those of the[Fe/H] (up to 0.03 dex) and varying from one specie to another,obtaining a chemical pattern difference between both methods. This meansthat condensation temperature Tc trends could also present a variation.We include an example showing that using non-solar-scaled opacities, theclassical solution cannot always verify the excitation and ionizationbalance conditions required for a model atmosphere. We consider that theuse of the non-solar-scaled opacities is not mandatory in everystatistical study with large samples of stars. However, for thosehigh-precision works whose results depend on the mutual comparison ofdifferent chemical species (such as Tc trends), we consider that it isworthwhile its application. To date, this is probably one of the moreprecise spectroscopic methods of stellar parameters derivation[abridged].