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A&A 416, 281-290 (2004)
DOI: 10.1051/0004-6361:20034466
Coronal versus photospheric abundances of stars with different activity levels
J. Sanz-Forcada1, F. Favata2 and G. Micela11 INAF - Osservatorio Astronomico di Palermo G. S. Vaiana, Piazza del Parlamento, 1, Palermo, 90134, Italy
2 Astrophysics Division - Research and Science Support Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
(Received 7 October 2003 / Accepted 6 November 2003 )
Abstract
We report a detailed analysis of the coronal abundance of 4 stars
with varying levels of activity and with accurately known
photospheric abundances. The coronal abundance is determined here
using a line flux analysis and a full determination of the
differential emission measure. Photospheric abundance values are
taken from the literature. Previous coronal abundance
determinations have generally been compared to solar photospheric
abundances; from this a number of general properties have been
inferred, such as the presence of a coronal metal depletion with an
inverse First Ionization Potential correlated with activity level.
Here we show that, when coronal abundances are
compared with real photospheric values for the individual stars, the
resulting pattern can be very different. Also, we present evidence
that, in some cases, the coronal metal abundance may not be uniform
in the corona; in particular it can vary with the
temperature of the emitting plasma.
Key words: stars: coronae -- stars: abundances -- stars: late-type -- X-rays: stars -- line: identification
Offprint request: J. Sanz-Forcada, jsanz@astropa.unipa.it
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