dc.contributor.author | Hoffman, J. | |
dc.contributor.author | Günther, H.M. | |
dc.contributor.author | Wright, N.J. | |
dc.date.accessioned | 2013-01-30T14:28:37Z | |
dc.date.available | 2013-01-30T14:28:37Z | |
dc.date.issued | 2012-11-10 | |
dc.identifier.citation | Hoffman , J , Günther , H M & Wright , N J 2012 , ' Constraints on the ubiquity of coronal X-ray cycles ' , The Astrophysical Journal , vol. 759 , no. 2 , 145 . https://doi.org/10.1088/0004-637X/759/2/145 | |
dc.identifier.issn | 0004-637X | |
dc.identifier.uri | http://hdl.handle.net/2299/9807 | |
dc.description | Copyright 2012 Elsevier B.V., All rights reserved. | |
dc.description.abstract | 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. | en |
dc.format.extent | 245674 | |
dc.language.iso | eng | |
dc.relation.ispartof | The Astrophysical Journal | |
dc.title | Constraints on the ubiquity of coronal X-ray cycles | en |
dc.contributor.institution | School of Physics, Astronomy and Mathematics | |
dc.contributor.institution | Science & Technology Research Institute | |
dc.contributor.institution | Centre for Astrophysics Research | |
dc.description.status | Peer reviewed | |
dc.identifier.url | http://www.scopus.com/inward/record.url?scp=84868135556&partnerID=8YFLogxK | |
rioxxterms.versionofrecord | 10.1088/0004-637X/759/2/145 | |
rioxxterms.type | Journal Article/Review | |
herts.preservation.rarelyaccessed | true | |