Abstract
The discovery of solar-like oscillations in the giant star ξ Hya (G7 III) was reported by Frandsen et al. (2002). Their frequency analysis was very limited due to alias problems in the data set (caused by single-site observations). The extent to which the aliasing affected their analysis was unclear due to the unknown damping time of the stellar oscillation modes. In this paper we describe a simulator created to generate time series of stochastically excited oscillations, which takes as input an arbitrary window function and includes both white and non-white noise. We also outline a new method to compare a large number of simulated time series with an observed time series to determine the damping time, amplitude, and limited information on the degree of the stochastically excited modes. For ξ Hya we find the most likely amplitude to be ∼ 2 m s−1, in good agreement with theory (Houdek and Gough, 2002), and the most likely damping time to be ∼ 2 days, which is much shorter than the theoretical value of 15–20 days calculated by Houdek and Gough (2002).
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Bedding, T. R. and Kjeldsen, H.: 2003, Astron. Soc. Austr. 20, 203.
Bedding, T. R., Kjeldsen, H., Butler, R. P., McCarthy, C., Marcy, G.W., O'Toole, S. J., Tinney, C. G., and Wright, J. T.: 2004, Astrophys. J., submitted.
Brown, T. M., Gilliland, R. L., Noyes, R. W., and Ramsey, L. W.: 1991, Astrophys. J. 368, 599.
Butler, R. P., Bedding, T. R., Kjeldsen, H., McCarthy, C., O'Toole, S. J., Tinney, C. G., Marcy, G.W., and Wright, J. T.: 2004, Astrophys. J. Lett., 600, 75.
Chang, H.-Y. and Gough, D. O.: 1998, Solar Phys. 181, 251.
De Ridder, J.: 2002, Time Series Simulator. Technical Report, Rømer Science Data Center, Aarhus Universitet.
De Ridder, J., Kjeldsen, H., Arentoft, T., and Claret, A.: 2003, ‘‘The EDDINGTON Light Curve Simulator’. Proc. 2nd Eddington Workshop, ESA-SP538.
Frandsen, S., Carrier, F., Aerts, C., Stello, D., Maas, T., Burnet, M., Bruntt, H., Teixeira, T. C., de Medeiros, J. R., Bouchy, F., Kjeldsen, H., Pijpers, F., and Christensen-Dalsgaard, J.: 2002, Astron. Astrophys. 394, L5.
Goldreich, P. and Keeley, D. A.: 1977, Astrophys. J. 212, 243.
Houdek, G. and Gough, D. O.: 2002, Monthly Notices Royal Astron. Soc. 336, L65.
Houdek, G., Balmforth, N. J., Christensen-Dalsgaard, J., and Gough, D. O.: 1999, Astron. Astrophys. 351, 582.
Kjeldsen, H.: 2003, Astrophys. J. Suppl. Series 284, 1.
Kjeldsen, H. and Bedding, T. R.: 1998, ‘MONS: A proposal for a Danish satellite’. in H. Kjeldsen and T. R. Bedding (eds.), The First MONS Workshop: Science with a Small Space Telescope, held in Aarhus, Denmark, June 29–30, 1998, Aarhus Universitet, p. 1.
Kjeldsen, H. and Frandsen, S.: 1992, Publ. Astron. Pacific 104, 413.
Leifsen, T., Andersen, B. N., and Toutain, T.: 2001, ‘Temporal Behaviour of Radial p-Modes’, in: ESA SP-464; SOHO 10/GONG 2000 Workshop: Helio-and Asteroseismology at the Dawn of the Millennium, p. 63.
Priestley, M. B.: 1981, Spectral Analysis and Time Series, Vol. 1, Probability and Mathematical Statistics, Academic Press, New York.
Stello, D.: 2002, ‘Detecting Solar-Like Oscillations in the Giant Star ξ Hydrae. New prospects for Asteroseismology throughout the HR-Diagram’. Master's thesis, Institut for Fysik og Astronomi, Aarhus Universitet. Available HTTP: http://www.phys.au.dk/~stello/Publications/thesis.pdf.
Teixeira, T. C.: 2002, private communication.
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Stello, D., Kjeldsen, H., Bedding, T.R. et al. Simulating stochastically excited oscillations: The mode lifetime of ξ Hya. Solar Physics 220, 207–228 (2004). https://doi.org/10.1023/B:SOLA.0000031388.64723.93
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DOI: https://doi.org/10.1023/B:SOLA.0000031388.64723.93