Asteroseismic surface gravity for evolved stars

Author(s)

S. Hekker, Y. Elsworth, B. Mosser, T. Kallinger, S. Basu, W. J. Chaplin, D. Stello

Abstract

Context. Asteroseismic surface gravity values can be important for

determining spectroscopic stellar parameters. The independent log (g)

value from asteroseismology can be used as a fixed value in the

spectroscopic analysis to reduce uncertainties because log (g) and

effective temperature cannot be determined independently from spectra.

Since 2012, a combined analysis of seismically and spectroscopically

derived stellar properties has been ongoing for a large survey with

SDSS/APOGEE and Kepler. Therefore, knowledge of any potential biases and

uncertainties in asteroseismic log (g) values is now becoming important.

Aims: The seismic parameter needed to derive log (g) is the

frequency of maximum oscillation power (νmax). Here, we

investigate the influence on the derived log (g) values of

νmax derived with different methods. The large frequency

separation between modes of the same degree and consecutive radial

orders (Δν) is often used as an additional constraint for

determining log (g). Additionally, we checked the influence of small

corrections applied to Δν on the derived values of log (g). Methods: We use methods extensively described in the literature to

determine νmax and Δν together with seismic

scaling relations and grid-based modelling to derive log (g).

Results: We find that different approaches to derive oscillation

parameters give results for log (g) with small, but different, biases

for red-clump and red-giant-branch stars. These biases are well within

the quoted uncertainties of ~0.01 dex (cgs). Corrections suggested in

the literature to the Δν scaling relation have no significant

effect on log (g); however, somewhat unexpectedly, method specific solar

reference values induce biases close to the uncertainties, which is not

the case when canonical solar reference values are used.

Organisation(s)

Department of Astrophysics

External organisation(s)

University of Birmingham, The University of Sydney, University of Amsterdam (UvA), Yale University, Université Paris VII - Paris-Diderot

Journal

Astronomy & Astrophysics

Volume

556

No. of pages

8

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/201321630

Publication date

08-2013

Peer reviewed

Yes

Austrian Fields of Science 2012

103004 Astrophysics, 103003 Astronomy

Keywords

Portal url

https://ucrisportal.univie.ac.at/en/publications/ce8e1440-a481-47c8-b491-ac484c54a7b4