Temperature Determination and Emission Measure Modeling
of the Coronae of Alpha Centauri and Procyon
A. Raassen, J. Kaastra, R. van der Meer, R. Mewe, M. Audard,
M. Guedel, J.-U. Ness, & E. Behar,
Institute: Astronomical Institute "Anton Pannekoek",
Amsterdam
Institute: Space Research Organization of the Netherlands
Institute: Paul Scherrer Institut
Institute: Hamburg University
Institute: Columbia University
Contact Email: raassen@astro.uva.nl
Abstract:
We have obtained the spectra of the coronae of Alpha Centauri and
Procyon using the Reflection Grating Spectrometer (RGS) on board
XMM-Newton and the Low Energy Transmission Grating
Spectrometer (LETGS) on board Chandra. From measured line fluxes of
H- and He-like lines of Carbon, Nitrogen and Oxygen and of strong
lines of Fe IX and Fe X temperature estimates and emission measures (EM)
have been obtained. For all three stars (Procyon, Alpha Cen (G2V),
and Alpha Cen (K1V)) the temperatures are in the regime
of 1-2 MK. The emission measure for Procyon is about
1 x 10^50 cm^-3 and for both components of Alpha Cen about
8 x 10^48 cm^-3. Global fits to the total spectrum using SPEX show
significant temperature components around 1 and 2 MK.
Self-consistent continuous emission measures have been constructed.
Alpha Cen B (K1V)
is somewhat hotter than its G2V companion.
Index Keywords: Alpha Cen ; Procyon ; Coronal spectra ; Chandra (LETGS) ;
XMM-Newton (RGS)
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Manuscript submitted: 2003-Nov-3
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.