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The corona and upper transition region of ε Eridani

Authors :
Carole Jordan
Jan-Uwe Ness
Source :
Monthly Notices of the Royal Astronomical Society. 385:1691-1708
Publication Year :
2008
Publisher :
Oxford University Press (OUP), 2008.

Abstract

We present analyses of observations of epsilon Eridani (K2 V) made with the Low Energy Transmission Grating Spectrometer on Chandra and the Extreme Ultraviolet Explorer, supplemented by observations made with the Space Telescope Imaging Spectrograph, the Far Ultraviolet Spectroscopic Explorer and the Reflection Grating Spectrometer on XMM-Newton. The observed emission lines are used to find relative element abundances, to place limits on the electron densities and pressures and to determine the mean apparent emission measure distribution. As in the previous paper by Sim & Jordan (2003a), the mean emitting area as a function of the electron temperature is derived by comparisons with a theoretical emission measure distribution found from energy balance arguments. The final model has a coronal temperature of 3.4 x 10^6 K, an electron pressure of 1.3 x 10^16 cm^-3 K at T_e = 2 x 10^5 K and an area filling factor of 0.14 at 3.2 x 10^5 K. We discuss a number of issues concerning the atomic data currently available. Our analyses are based mainly on the latest version of CHIANTI (v5.2). We conclude that the Ne/O relative abundance is 0.30, larger than that recommended from solar studies, and that there is no convincing evidence for enhanced coronal abundances of elements with low first ionization potentials.

Details

ISSN :
13652966 and 00358711
Volume :
385
Database :
OpenAIRE
Journal :
Monthly Notices of the Royal Astronomical Society
Accession number :
edsair.doi...........770bb149254316725f19c0cb7d0da460
Full Text :
https://doi.org/10.1111/j.1365-2966.2007.12757.x