Editing Arcturus (section)

===Oscillations===
As one of the brightest stars in the sky, Arcturus has been the subject of a number of studies in the emerging field of [[asteroseismology]]. Belmonte and colleagues carried out a radial velocity (Doppler shift of spectral lines) study of the star in April and May 1988, which showed variability with a frequency of the order of a few [[microhertz]] (μHz), the highest peak corresponding to 4.3&nbsp;μHz (2.7&nbsp;days) with an amplitude of 60 ms<sup>−1</sup>, with a [[frequency separation]] of c.&nbsp;5&nbsp;μHz. They suggested that the most plausible explanation for the variability of Arcturus is stellar oscillations.<ref name=belmonte1990/>

Asteroseismological measurements allow direct calculation of the mass and radius, giving values of {{Val|0.8|0.2|u=solar mass}} and {{Val|27.9|3.4|ul=solar radius}}. This form of modelling is still relatively inaccurate, but a useful check on other models.<ref name=kallinger/>