Mewe, R. ; Drake, S. A. ; Kaastra, J. S. ; Schrijver, C. J. ; Drake, J. J. ; Güdel, M. ; Schmitt, J. H. M. M. ; Singh, K. P. ; White, N. E. (1998) α Centauri: coronal temperature structure and abundances from ASCA observations Astronomy & Astrophysics, 339 (2). pp. 545-552. ISSN 0004-6361
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Official URL: http://aa.springer.de/bibs/8339002/2300545/small.h...
Abstract
We have analyzed the X-ray spectrum of the nearby binary α Cen AB (G2V+K1V) that has been obtained from observations with ASCA. The coronal temperature structure and abundances have been derived from multi-temperature fitting and confirmed by a differential emission measure analysis. The corona as seen by ASCA is essentially isothermal with a temperature around 0.3 keV, consistent with the evolutionary picture of coronae of aging solar-type stars. A comparison between the measurements from various instruments indicates a source variability in the coronal flux (which precludes the joint fitting of data from different instruments taken at different epochs) and temperature structure consistent with that discovered in a series of ROSAT observations. The elemental abundances agree with solar photospheric abundances for Ne, Si, and Fe at 1σ level, while O appears to be underabundant by a factor of about 3 relative to solar photospheric values, and Mg overabundant by a factor of a few. The abundance ratios with respect to Fe are better determined: [O/Fe]=0.4±0.14 (× solar, etc.), [Mg/Fe]=4±1, [Ne/Fe]=1±0.3, and [Si/Fe]=6±4.
Item Type: | Article |
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Source: | Copyright of this article belongs to EDP Sciences. |
Keywords: | Stars: Coronae; Stars: Individual: α Cen; Stars: Abundances; X-rays: Stars |
ID Code: | 58997 |
Deposited On: | 03 Sep 2011 12:12 |
Last Modified: | 18 May 2016 09:42 |
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