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Modelling the colour‐brightness relation of chromospherically active stars
Author(s) -
AarumUlvås V.,
Henry G. W.
Publication year - 2005
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200410392
Subject(s) - starspot , physics , astrophysics , brightness , stars , flux (metallurgy) , astronomy , materials science , metallurgy
The photometric flux of chromospherically active, spotted stars generally becomes redder and fainter when large starspots rotate into view on the stellar disc. However, some of the most active RS CVn systems show a bluer flux as they get fainter. Modelling of one such system (UX Ari) has shown that hot, bright, photospheric facular regions accompanying the cool, dark spots on the cooler, more active component are a possible explanation. The bluer flux of the hotter, less active component does not appear to be sufficient to explain the observed behaviour. We have begun a search for additional chromospherically active stars with a similar relation between colour and brightness, to investigate whether these relations can be explained in the same way. Our results for V711 Tau and RS CVn are presented here, and we conclude that the photospheric faculae remain the most probable explanation for the observed behaviour. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)