Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Why do some spotted stars become bluer as they become fainter?   Chromospherically active, spotted stars generally become redder as well as
fainter when large starspots rotate into view on the stellar disc. However, the
RS CVn system UX Ari (a triple-lined system), becomes bluer as it gets fainter.
One possible explanation is that hot, bright facular regions accompany the
cool, dark photospheric spots of the active component. The bluer flux of the
hotter, inactive 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 are presented here, and we conclude that the faculae
explanation holds also in this case.

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The categories of this paper are: solv-int
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph
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The categories of this paper are: quant-ph
16
The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: alg-geom