To expand the range in the colour-magnitude diagram where asteroseismology can be applied, we organized a photometry campaign to find evidence for solar-like oscillations in giant stars in the globular cluster M4. The aim was to detect the comb-like p-mode structure characteristic for solar-like oscillations in the amplitude spectra. The two dozen main target stars are in the region of the bump stars and have luminosities in the range 50-140 Lsun. We collected 6160 CCD frames and light curves for about 14000 stars were extracted. We obtain high quality light curves for the K giants, but no clear oscillation signal is detected. High precision differential photometry is possible even in very crowded regions like the core of M4. Solar-like oscillations are probably present in K giants, but the amplitudes are lower than classical scaling laws predict.
@article{arxiv.0708.2010,
title = {A search for solar-like oscillations in K giants in the globular cluster M4},
author = {S. Frandsen and H. Bruntt and F. Grundahl and G. Kopacki and H. Kjeldsen and T. Arentoft and D. Stello and T. R. Bedding and A. P. Jacob and R. L. Gilliland and P. D. Edmonds and E. Michel and J. Matthiesen},
journal= {arXiv preprint arXiv:0708.2010},
year = {2009}
}
Comments
14 pages, 16 figures, accepted for publication in A&A