X-ray and extreme-ultraviolet emission from the coronae of Capella

Details X-ray and extreme-ultraviolet emission from the coronae of Capella X-ray and extreme-ultraviolet emission from the coronae of Capella

Aug 2001

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001mnras.325.1500p&link_type=abstract

Monthly Notices of the Royal Astronomical Society, Volume 325, Issue 4, pp. 1500-1510.

Astronomy and Astrophysics

Astronomy

30

Sun: Flares, Sun: X-Rays, Gamma-Rays, Stars: Activity, Stars: Coronae, Stars: Individual: Capella, X-Rays: Stars

Scientific paper

The primary objective of this work is the analysis and interpretation of coronal observations of Capella obtained in 1999 September with the High Energy Transmission Grating Spectrometer on the Chandra X-ray Observatory and the Extreme Ultraviolet Explorer (EUVE). He-like lines of O (Ovii) are used to derive a density of 1.7×1010cm-3 for the coronae of the binary, consistent with the upper limits derived from Fexxi, Neix and Mgxi line ratios. Previous estimates of the electron density based on Fexxi should be considered as upper limits. We construct emission measure distributions and compare the theoretical and observed spectra to conclude that the coronal material has a temperature distribution that peaks around 4-6MK, implying that the coronae of Capella were significantly cooler than in the previous years. In addition, we present an extended line list with over 100 features in the 5-24Å wavelength range, and find that the X-ray spectrum is very similar to that of a solar flare observed with SMM. The observed to theoretical Fexvii 15.012-Å line intensity reveals that opacity has no significant effect on the line flux. We derive an upper limit to the optical depth, which we combine with the electron density to derive an upper limit of 3000km for the size of the Fexvii emitting region. In the same context, we use the Siiv transition region lines of Capella from HST/Goddard High-Resolution Spectrometer observations to show that opacity can be significant at T=105K, and derive a path-length of ~75km for the transition region. Both the coronal and transition region observations are consistent with very small emitting regions, which could be explained by small loops over the stellar surfaces.

Affiliated with

Also associated with

No associations

Rating

X-ray and extreme-ultraviolet emission from the coronae of Capella does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with X-ray and extreme-ultraviolet emission from the coronae of Capella, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and X-ray and extreme-ultraviolet emission from the coronae of Capella will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-802378