Mon. Not. R. Astron. Soc. 382, L48−L52, 2007
© RAS
Asteroseismology of red giants: photometric observations of Arcturus by SMEI
N.J. Tarrant, W.J. Chaplin, Y. Elsworth, S.A. Spreckley, I.R. Stevens
School of Physics and Astronomy, Univ. of Birmingham, Birmingham, UK
Abstract
We present new results on oscillations of the K1.5 III giant Arcturus
(α Boo), from analysis of just over 2.5 yr of precise photometric
observations made by the Solar Mass Ejection Imager on board the Coriolis
satellite. A strong mode of oscillation is uncovered by the analysis,
having frequency 3.51±0.03 μHz. By fitting its mode peak, we are
able to offer a highly constrained direct estimate of the damping time
(τ = 24 ± 1 d). The data also hint at the possible presence of
several radial-mode overtones, and maybe some non-radial modes. We are
also able to measure the properties of the granulation on the star,
with the characteristic time-scale for the granulation estimated to
be ~0.50 ± 0.05 d.