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Linsky, Jeffrey
Contact Email: jlinsky@jila.colorado.edu
Institute: JILA/University of Colorado
First Coauthor: Rachel Osten
Institute: CASA/University of Colorado
Second Coauthor: Alec Brown
Institute: CASA/University of Colorado
Research URL:http://jilawww.colorado.edu/~jlinsky/
Subject Area: Stellar Atmospheres, Circumstellar Material
Waveband: X-rays
Technique: Spectroscopy
Presentation: Poster Display
Title: Crazy Coronal Abundances
Abstract: Chandra high resolution X-ray spectra of active late-type
stars and binary systems show a pattern of strange coronal
abundances. Elements with low first ionization potential
(FIP < 10 eV) like Fe are underabundant, whereas elements
with FIP > 10 eV (in particular Ne and Ar) are overabundance
compared to solar photospheric values. Preliminary evidence
for this pattern was already seen in the ROSAT and ASCA
data, but the the Chandra and XMM-Newton data greatly
strengthen the case. The coronal abundances in active stars
are especially interesting because the solar corona shows
the opposite effect (FIP deficiency). I will summarize the
new results, compare with the solar abundance results, and
comment on the reliability of the stellar abundance
anomalies. The
solar FIP and stellar anti-FIP effects can be understood (at
least in part) in terms of fractionation effects in the
chromosphere and perhaps diffusion in the corona. I will
compare theoretical predictions with the observed crazy
coronal abundances.
Next: Catalano, Santo
Up: No Title
Previous: Gayley, Kenneth
Cool Stars 12
2001-07-17