Solar-like oscillations in the G2 subgiant beta Hydri from dual-site observations

We have observed oscillations in the nearby G2 subgiant star beta Hyi using high-precision velocity observations obtained over more than a week with the HARPS and UCLES spectrographs. The oscillation frequencies show a regular comb structure, as expected for solar-like oscillations, but with several...

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Bibliographic Details
Published in:arXiv.org 2007-05
Main Authors: Bedding, Timothy R, Kjeldsen, Hans, Arentoft, Torben, Bouchy, Francois, Brandbyge, Jacob, Brewer, Brendon J, Butler, R Paul, Christensen-Dalsgaard, Joergen, Dall, Thomas, Frandsen, Soeren, Karoff, Christoffer, Kiss, Laszlo L, Mario J P F G Monteiro, Pijpers, Frank P, Teixeira, Teresa C, Tinney, C G, Baldry, Ivan K, Carrier, Fabien, O'Toole, Simon J
Format: Article
Language:English
Subjects:
Oscillation modes
Solar oscillations
Spectrographs
Stellar age
Subgiant stars
Online Access:Get full text
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Summary:We have observed oscillations in the nearby G2 subgiant star beta Hyi using high-precision velocity observations obtained over more than a week with the HARPS and UCLES spectrographs. The oscillation frequencies show a regular comb structure, as expected for solar-like oscillations, but with several l=1 modes being strongly affected by avoided crossings. The data, combined with those we obtained five years earlier, allow us to identify 28 oscillation modes. By scaling the large frequency separation from the Sun, we measure the mean density of beta Hyi to an accuracy of 0.6%. The amplitudes of the oscillations are about 2.5 times solar and the mode lifetime is 2.3 d. A detailed comparison of the mixed l=1 modes with theoretical models should allow a precise estimate of the age of the star.
ISSN:2331-8422
DOI:10.48550/arxiv.0703747