Issue |
A&A
Volume 515, June 2010
|
|
---|---|---|
Article Number | A43 | |
Number of page(s) | 9 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/200912777 | |
Published online | 08 June 2010 |
Line-profile variations of stochastically excited oscillations in four evolved stars *
1
School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK e-mail: saskia@bison.ph.bham.ac.uk
2
Instituut voor Sterrenkunde, Katholieke Universiteit Leuven,
Celestijnenlaan 200 D, 3001 Leuven, Belgium
3
Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium
4
Department of Astrophysics, IMAP, University of Nijmegen, PO Box 9010,
6500 GL Nijmegen, The Netherlands
Received:
29
June
2009
Accepted:
8
February
2010
Context. Since solar-like oscillations were first detected in red-giant stars, the presence of non-radial oscillation modes has been debated. Spectroscopic line-profile analysis was used in the first attempt to perform mode identification, which revealed that non-radial modes are observable. Despite the fact that the presence of non-radial modes could be confirmed, the degree or azimuthal order could not be uniquely identified. Here we present an improvement to this first spectroscopic line-profile analysis.
Aims. We aim to study line-profile variations in stochastically excited solar-like oscillations of four evolved stars to derive the azimuthal order of the observed mode and the surface rotational frequency.
Methods. Spectroscopic line-profile analysis is applied to cross-correlation functions, using the Fourier parameter fit method on the amplitude and phase distributions across the profiles.
Results. For four evolved stars, β Hydri (G2IV), ϵ Ophiuchi (G9.5III), η Serpentis (K0III) and δ Eridani (K0IV) the line-profile variations reveal the azimuthal order of the oscillations with an accuracy of ±1. Furthermore, our analysis reveals the projected rotational velocity and the inclination angle. From these parameters we obtain the surface rotational frequency.
Conclusions. We conclude that line-profile variations in cross-correlation functions behave differently for different frequencies and provide additional information about the surface rotational frequency and azimuthal order.
Key words: stars: oscillations / stars: individual: ϵ Ophiuchi / stars: individual: η Serpentis / stars: individual: δ Eridani / stars: individual: β Hydri / line: profiles
The software package FAMIAS developed in the framework of the FP6 European Coordination Action HELAS (http://www.helas-eu.org) has been used in this research.
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.