Testing different methods for atmospheric parameters determination. The case study of the Am star HD 71297

Abstract

In this paper, we present a detailed spectroscopic analysis of the suspected marginal Am star HD 71297. Our goal is to test the accuracy of two different approaches to determine the atmospheric parameters: effective temperature, gravity, projected rotational velocity and chemical abundances. The methods used in this paper are: classical spectral synthesis and the Versatile Wavelength Analysis (VWA) software. Since our star is bright and very close to the Sun, we were able to determine its effective temperature and gravity directly through photometric, interferometric and parallax measurements. The values found were taken as reference to which we compare the values derived by spectroscopic methods. Our analysis leads us to conclude that the spectroscopic methods considered in this study to derive fundamental parameters give consistent results, if we consider all the sources of experimental errors, that have been discussed in the text. In addition, our study shows that the spectroscopic results are quite as accurate as those derived from direct measurements. As for the specific object analysed here, according to our analysis, HD 71297 has chemical abundances not compatible with the previous spectral classification. We found moderate underabundances of carbon, sodium, magnesium and iron-peak elements, while oxygen, aluminium, silicon, sulphur and heavy elements (Z ≥ 39) are solar in content. This chemical pattern has been confirmed by the calculations performed with both methods.© 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.