Asteroseismic investigations based on the wealth of data now available, in particular from the CoRoT and Kepler missions, require a good understanding of the relation between the observed quantities and the properties of the underlying stellar structure. Kallinger et al. found a relation between their determination of the asymptotic phase of radial oscillations in evolved stars and the evolutionary state, separating ascending-branch red giants from helium-burning stars in the ‘red clump’. Here, we provide a detailed analysis of this relation, which is found to derive from differences between these two classes of stars in the thermodynamic state of the convective envelope. There is potential for distinguishing red giants and clump stars based on the phase determined from observations that are too short to allow distinction based on determination of the period spacing for mixed modes. The analysis of the phase may also point to a better understanding of the potential for using the helium-ionization-induced acoustic glitch to determine the helium abundance in the envelopes of these stars.
|Number of pages||9|
|Journal||Royal Astronomical Society. Monthly Notices|
|Early online date||29 Oct 2014|
|Publication status||Published - 21 Dec 2014|
- stars: atmospheres
- stars: evolution
- stars: oscillations