文章基本信息

标题：Further evidence for a sub-year magnetic chromospheric activity cycle and activity phase jumps in the planet host τ Boötis
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作者：J. H. M. M. Schmitt ; J. H. M. M. Schmitt ; M. Mittag 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2017
卷号：600
页码：1-5
DOI：10.1051/0004-6361/201629429
语种：English
出版社：EDP Sciences
摘要：We examine the S-index data, obtained in the context of the Mount Wilson H&K project for the nearby F-type star τ Boo, for the presence of possible cyclic variations on timescales below one year and “phase jump” episodes in the observed S-index activity levels, to determine whether such features are persistent properties of the chromospheric activity of τ Boo and possibly other late-type stars. Within the Mount Wilson H&K project τ Boo was observed during 1278 individual nights, albeit with a very inhomogeneous coverage ranging from 2 to 137 observations per year. Our analysis shows that periodical variations with timescales on the order of 110–120 days are a persistent feature of the Mount Wilson data set. Furthermore we provide further examples of “phase jump” episodes, when the observed S-index activity drops from maximum to minimum levels on timescales of one to two weeks, hence such features also appear to occur on a more or less regular basis in τ Boo.
关键词：stars: activity;stars: chromospheres;stars: late-type