Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-11T05:24:35.205Z Has data issue: false hasContentIssue false
  • English
  • Français

Confronting the Gaia and NLTE spectroscopic parallaxes for the FGK stars

Published online by Cambridge University Press:  07 March 2018

Tatyana Sitnova ,
Lyudmila Mashonkina  and
Yury Pakhomov
Tatyana Sitnova
Affiliation:
Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 119017, Moscow, Russia email: sitnova@inasan.ru
Lyudmila Mashonkina
Affiliation:
Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 119017, Moscow, Russia email: sitnova@inasan.ru
Yury Pakhomov
Affiliation:
Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 119017, Moscow, Russia email: sitnova@inasan.ru
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The understanding of the chemical evolution of the Galaxy relies on the stellar chemical composition. Accurate atmospheric parameters is a prerequisite of determination of accurate chemical abundances. For late type stars with known distance, surface gravity (log g) can be calculated from well-known relation between stellar mass, Teff, and absolute bolometric magnitude. This method weakly depends on model atmospheres, and provides reliable log g. However, accurate distances are available for limited number of stars. Another way to determine log g for cool stars is based on ionisation equilibrium, i.e. consistent abundances from lines of neutral and ionised species. In this study we determine atmospheric parameters moving step-by-step from well-studied nearby dwarfs to ultra-metal poor (UMP) giants. In each sample, we select stars with the most reliable Teff based on photometry and the distance-based log g, and compare with spectroscopic gravity calculated taking into account deviations from local thermodinamic equilibrium (LTE). After that, we apply spectroscopic method of log g determination to other stars of the sample with unknown distances.

Keywords

stars: fundamental parametersabundances
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 12 , Symposium S330: Astrometry and Astrophysics in the Gaia sky , April 2017 , pp. 327 - 328
Copyright
Copyright © International Astronomical Union 2018 

References

Alonso, A., Arribas, S., & Martinez-Roger, C., 1996, A&AS, 117, 227 Google Scholar
Casagrande, L., Schönrich, R., Asplund, M., Cassisi, S., Ramírez, I., Meléndez, J., Bensby, T., & Feltzing, S., 2011, A&A, 530, A138 Google Scholar
Gaia Collaboration, Brown, A. G. A., Vallenari, A., Prusti, T., de Bruijne, J. H. J., Mignard, F. et al., 2016, A&A, 595, A2 Google Scholar
Ramírez, I. & Meléndez, J., 2005, ApJ, 626, 465 CrossRefGoogle Scholar
van Leeuwen, F., 2007, A&A, 474, 653 Google Scholar
Yi, S. K., Demarque, P., & Kim, Y.-C., 2004, Ap&SS, 291, 261 Google Scholar