Issue |
A&A
Volume 399, Number 1, February III 2003
|
|
---|---|---|
Page(s) | L11 - L14 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20030085 | |
Published online | 05 February 2003 |
Letter to the Editor
Why does the spotted UX Ari system get bluer as it gets darker?
Institute of Theoretical Astrophysics, PO Box 1029 Blindern, 0315 Oslo, Norway
Corresponding author: V. Aarum Ulvås, v.a.ulvas@astro.uio.no
Received:
2
October
2002
Accepted:
12
January
2003
We present simplified calculations of UX Ari
colour index and
V magnitude for a range of parameter values. The results of our
calculations are compared to previously published measurements. We
find that our calculations reproduce the well established
colour-brightness relation (UX Ari gets bluer as it gets darker) only
if the dark spots
on the surface of the K star are accompanied by bright facular
areas. There is currently an ambiguity between the temperature of
the
facular areas and the portion of the stellar surface occupied by
them.
Key words: stars: activity / binaries: spectroscopic / stars: individual: UX Ari / stars: late-type / starspots
© ESO, 2003
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