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Testing asteroseismic radii of dwarfs and subgiants with Kepler and Gaia

Sahlholdt, C. L. LU ; Silva Aguirre, V. ; Casagrande, L. ; Mosumgaard, J. R. and Bojsen-Hansen, M. (2018) In Monthly Notices of the Royal Astronomical Society 476(2). p.1931-1941
Abstract

We test asteroseismic radii of Kepler main-sequence and subgiant stars by deriving their parallaxes which are compared with those of the first Gaia data release. We compute radii based on the asteroseismic scaling relations as well as by fitting observed oscillation frequencies to stellar models for a subset of the sample, and test the impact of using effective temperatures from either spectroscopy or the infrared flux method. An offset of 3 per cent, showing no dependency on any stellar parameters, is found between seismic parallaxes derived from frequency modelling and those from Gaia. For parallaxes based on radii from the scaling relations, a smaller offset is found on average; however, the offset becomes temperature dependent which... (More)

We test asteroseismic radii of Kepler main-sequence and subgiant stars by deriving their parallaxes which are compared with those of the first Gaia data release. We compute radii based on the asteroseismic scaling relations as well as by fitting observed oscillation frequencies to stellar models for a subset of the sample, and test the impact of using effective temperatures from either spectroscopy or the infrared flux method. An offset of 3 per cent, showing no dependency on any stellar parameters, is found between seismic parallaxes derived from frequency modelling and those from Gaia. For parallaxes based on radii from the scaling relations, a smaller offset is found on average; however, the offset becomes temperature dependent which we interpret as problems with the scaling relations at high stellar temperatures. Using the hotter infrared flux method temperature scale, there is no indication that radii from the scaling relations are inaccurate by more than about 5 per cent. Taking the radii and masses from the modelling of individual frequencies as reference values, we seek to correct the scaling relations for the observed temperature trend. This analysis indicates that the scaling relations systematically overestimate radii and masses at high temperatures, and that they are accurate to within 5 per cent in radius and 13 per cent in mass formain-sequence stars with temperatures below 6400 K. However, further analysis is required to test the validity of the corrections on a star-by-star basis and for more evolved stars.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Asteroseismology, Parallaxes, Stars: fundamental parameters, Stars: oscillations
in
Monthly Notices of the Royal Astronomical Society
volume
476
issue
2
pages
11 pages
publisher
Oxford University Press
external identifiers
  • scopus:85052516346
ISSN
0035-8711
DOI
10.1093/mnras/sty319
language
English
LU publication?
yes
id
e3b89d22-ba44-440c-b474-07e4cc6cdc40
date added to LUP
2018-09-27 12:33:10
date last changed
2020-04-02 02:05:43
@article{e3b89d22-ba44-440c-b474-07e4cc6cdc40,
  abstract     = {<p>We test asteroseismic radii of Kepler main-sequence and subgiant stars by deriving their parallaxes which are compared with those of the first Gaia data release. We compute radii based on the asteroseismic scaling relations as well as by fitting observed oscillation frequencies to stellar models for a subset of the sample, and test the impact of using effective temperatures from either spectroscopy or the infrared flux method. An offset of 3 per cent, showing no dependency on any stellar parameters, is found between seismic parallaxes derived from frequency modelling and those from Gaia. For parallaxes based on radii from the scaling relations, a smaller offset is found on average; however, the offset becomes temperature dependent which we interpret as problems with the scaling relations at high stellar temperatures. Using the hotter infrared flux method temperature scale, there is no indication that radii from the scaling relations are inaccurate by more than about 5 per cent. Taking the radii and masses from the modelling of individual frequencies as reference values, we seek to correct the scaling relations for the observed temperature trend. This analysis indicates that the scaling relations systematically overestimate radii and masses at high temperatures, and that they are accurate to within 5 per cent in radius and 13 per cent in mass formain-sequence stars with temperatures below 6400 K. However, further analysis is required to test the validity of the corrections on a star-by-star basis and for more evolved stars.</p>},
  author       = {Sahlholdt, C. L. and Silva Aguirre, V. and Casagrande, L. and Mosumgaard, J. R. and Bojsen-Hansen, M.},
  issn         = {0035-8711},
  language     = {eng},
  month        = {05},
  number       = {2},
  pages        = {1931--1941},
  publisher    = {Oxford University Press},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {Testing asteroseismic radii of dwarfs and subgiants with Kepler and Gaia},
  url          = {http://dx.doi.org/10.1093/mnras/sty319},
  doi          = {10.1093/mnras/sty319},
  volume       = {476},
  year         = {2018},
}