An asteroseismic signature of helium ionization
| dc.creator | Houdek, G. | |
| dc.creator | Gough, D. O. | |
| dc.date | 2006-12-01 | |
| dc.date.accessioned | 2026-07-07T10:21:07Z | |
| dc.date.available | 2026-07-07T10:21:07Z | |
| dc.description | We investigate the influence of the ionization of helium on the low-degree acoustic oscillation frequencies in model solar-type stars. The signature in the oscillation frequencies characterizing the ionization-induced depression of the first adiabatic exponent $γ$ is a superposition of two decaying periodic functions of frequency $ν$, with `frequencies' that are approximately twice the acoustic depths of the centres of the Helium I and Helium II ionization regions. That variation is probably best exhibited in the second frequency difference $Δ_2ν_{n,l}\equivν_{n-1,l}-2ν{n,l}+ν_{n+1,l}$. We show how an analytic approximation to the variation of $γ$ leads to a simple representation of this oscillatory contribution to $Δ_2ν$ which can be used to characterize the $γ$ variation, our intention being to use it as a seismic diagnostic of the helium abundance of the star. We emphasize that the objective is to characterize $γ$, not merely to find a formula for $Δ_2ν$ that reproduces the data. | |
| dc.description | 22 pages, 16 figures, accepted by MNRAS on 21 November 2006 | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0612030 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0612030 | |
| dc.identifier | Mon.Not.Roy.Astron.Soc.375:861-880,2007 | |
| dc.identifier | doi:10.1111/j.1365-2966.2006.11325.x | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/175069 | |
| dc.subject | Astrophysics | |
| dc.title | An asteroseismic signature of helium ionization | |
| dc.type | text |