2012/09/23 by John Hoffman, Hans Moritz Günther, Nick Wright +1 · 4 citations
Physics and Astronomy · #Algorithm #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Flux (metallurgy) #Gamma-ray bursts and supernovae #Light curve #Monte Carlo method #Periodogram #Physics #Stars #Statistics #Stellar, planetary, and galactic studies #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/759/2/145
published in The Astrophysical Journal 759(2), 145 (IOP Publishing) · 11 pages, 6 figures
arxiv created 2012/09/23 · openalex publication_date 2012/10/29 · arxiv updated 2012/10/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Stellar activity cycles are known to be a widespread phenomenon amongst moderately active solar- and late-type stars from long-term periodic variations in chromospheric Ca ii H and K emission lines, yet to date, only a handful of coronal X-ray cycles are known. We have surveyed serendipitously observed stellar sources in fields observed multiple times in the last decade by XMM-Newton and present our analysis of nine stars from six fields. Since our sample is flux-limited, it is strongly biased toward higher levels of X-ray activity. We fit a single temperature apec spectrum to each source and search for significant periodicities using a Lomb–Scargle periodogram. We use a Monte Carlo (MC) algorithm to yield robust analysis of the statistical significance of cycle detections and non-detections. None of the nine stellar light curves show any convincing indications of periodicity. From MC simulations, we simulate the detection capabilities of our methodology and, assuming a uniform distribution of cycle periods and strengths over the domain searched, we conclude with 95% confidence that less than 72% of the stars represented by our sample of active stars have 5–13 year coronal X-ray cycles.