Issue |
A&A
Volume 413, Number 3, January III 2004
|
|
---|---|---|
Page(s) | 1095 - 1104 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20031575 | |
Published online | 07 January 2004 |
The corona of HD 199178 (V 1794 Cygni)
European Space Agency, ESTEC - Postbus 299, 2200 AG Noordwijk, The Netherlands
Corresponding author: pgondoin@rssd.esa.int
Received:
20
May
2003
Accepted:
1
October
2003
HD 199178 (V 1794 Cygni), a chromospherically active late-type giant with a high X-ray luminosity, was observed by the
XMM-Newton space observatory. Series of lines of highly ionized Fe and several Lyman
lines of hydrogen-like ions are visible in the reflection grating
spectra, most notably from O and Ne. Analysis results suggest a
scenario where the corona of HD 199178 is dominated by large magnetic
structures similar in size to interconnecting loops between solar
active regions but significantly hotter. The surface area coverage of
these active regions may approach up to a 90%. An hypothesis is
that the interaction of these structures themselves induces a flaring
activity in a small scale not visible in the EPIC light curves that is
responsible for heating HD 199178 plasma to coronal temperatures of K. The intense X-ray activity of HD 199178 is related to
its evolutionary position at the bottom of the red giant branch. It is
anticipated that its rotation will spin-down in the future with the
effect of decreasing its helicity related, dynamo driven activity and
suppressing large scale magnetic structures in its corona.
Key words: stars: individual: HD 199178 / stars: activity / stars: coronae / stars: evolution / stars: late-type / stars: x-ray
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.