2005/04/25 by H. Bruntt, H. Kjeldsen, Derek L. Buzasi +2 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/462401
published as Astrophys.J. 633 (2005) 440-446 · 23 pages, 12 figures, submitted to ApJ; v2 revisions: one reference corrected and a comment in Figure 7 corrected
arxiv created 2005/04/25 · openalex publication_date 2005/10/25 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We report evidence for the granulation signal in the star Procyon A, based on two photometric time series from the star tracker on the WIRE satellite. The power spectra show evidence of excess power around 1 mHz, consistent with the detection of p -modes reported from radial velocity measurements. We see a significant increase in the noise level below 3 mHz, which we interpret as the granulation signal. We have made a large set of numerical simulations to constrain the amplitude and timescale of the granulation signal and the amplitude of the oscillations. We find that the timescale for granulation is Γ gran = 750 ± 200 s, the granulation amplitude is 1.8 ± 0.3 times solar, and the amplitude of the p -modes is 8.5 ± 2 ppm. We found the distribution of peak heights in the observed power spectra to be consistent with that expected from p -mode oscillations. However, the quality of the data is not sufficient to measure the large separation or to detect a comblike structure, as seen in the p -modes of the Sun. Comparison with the recent negative result from the MOST satellite reveals that the MOST data must have an additional noise source that prevented the detection of oscillations.