Shape of a slowly rotating star measured by asteroseismology.

ABSTRACT: Stars are not perfectly spherically symmetric. They are deformed by rotation and magnetic fields. Until now, the study of stellar shapes has only been possible with optical interferometry for a few of the fastest-rotating nearby stars. We report an asteroseismic measurement, with much better precision than interferometry, of the asphericity of an A-type star with a rotation period of 100 days. Using the fact that different modes of oscillation probe different stellar latitudes, we infer a tiny but significant flattening of the star's shape of ΔR/R = (1.8 ± 0.6) × 10^-6. For a stellar radius R that is 2.24 times the solar radius, the difference in radius between the equator and the poles is ΔR = 3 ± 1 km. Because the observed ΔR/R is only

SUBMITTER: Gizon L 

PROVIDER: S-EPMC5262460 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature