Bibcode
Jönsson, H.; Ryde, N.; Nordlander, T.; Pehlivan Rhodin, A.; Hartman, H.; Jönsson, P.; Eriksson, K.
Bibliographical reference
Astronomy and Astrophysics, Volume 598, id.A100, 11 pp.
Advertised on:
2
2017
Journal
Citations
36
Refereed citations
36
Description
Context. The Galactic bulge is an intriguing and significant part of our
Galaxy, but it is hard to observe because it is both distant and covered
by dust in the disk. Therefore, there are not many high-resolution
optical spectra of bulge stars with large wavelength coverage, whose
determined abundances can be compared with nearby, similarly analyzed
stellar samples. Aims: We aim to determine the diagnostically
important alpha elements of a sample of bulge giants using
high-resolution optical spectra with large wavelength coverage. The
abundances found are compared to similarly derived abundances from
similar spectra of similar stars in the local thin and thick disks. In
this first paper we focus on the solar neighborhood reference sample.
Methods: We used spectral synthesis to derive the stellar
parameters as well as the elemental abundances of both the local and
bulge samples of giants. We took special care to benchmark our method of
determining stellar parameters against independent measurements of
effective temperatures from angular diameter measurements and surface
gravities from asteroseismology. Results: In this first paper we
present the method used to determine the stellar parameters and
elemental abundances, evaluate them, and present the results for our
local disk sample of 291 giants. Conclusions: When comparing our
determined spectroscopic temperatures to those derived from angular
diameter measurements, we reproduce these with a systematic difference
of +10 K and a standard deviation of 53 K. The spectroscopic gravities
reproduce those determined from asteroseismology with a systematic
offset of +0.10 dex and a standard deviation of 0.12 dex. When it comes
to the abundance trends, our sample of local disk giants closely follows
trends found in other works analyzing solar neighborhood dwarfs, showing
that the much brighter giant stars are as good abundance probes as the
often used dwarfs.
Based on observations made with the Nordic Optical Telescope (programs
51-018 and 53-002), operated by the Nordic Optical Telescope Scientific
Association at the Observatorio del Roque de los Muchachos, La Palma,
Spain, of the Instituto de Astrofisica de Canarias, and on spectral data
retrieved from PolarBase at Observatoire Midi
Pyrénées.Full Tables A.1 and A.3 are only available at the
CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/598/A100