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Astron. Astrophys. 363, 667-670 (2000)
Research Note
An X-ray flare from the Lindroos binary system HD 560
B. Stelzer and
N. Huélamo
Max-Planck-Institut für extraterrestrische Physik, 85740 Garching, Germany
Received 23 August 2000 / Accepted 11 October 2000
Abstract
We report on a large X-ray flare from the Lindroos binary system HD 560 during a pointed ROSAT PSPC observation. HD 560 is composed of a B9 and a G5 type star. The late-type companions in bound Lindroos binaries are Post T Tauri star (PTTS) candidates, i.e. pre-main sequence stars on their final approach to the main sequence. Strong (magnetic) activity is, therefore, expected for the G star, in contrast to the late-B type component for which no mechanism of X-ray production is known. The system is unresolved in the ROSAT image.
During outburst the count rate has changed by at least a factor of
2, and presumably more (the maximum was not observed). The peak
luminosity measured is ![[FORMULA]](img1.gif)
, comparable to
the largest values derived for flares on pre-main sequence T Tauri
stars. A two-temperature model for thermal emission from a hot,
optically thin plasma shows an increase of the higher temperature as a
result of coronal heating during the flare. The lower temperatures do
not change during outburst.
Key words: X-rays:
stars 
stars: binaries:
general
stars: individual:
HD 560
stars:
late-type
stars: activity
Send offprint requests to: B. Stelzer
Correspondence to: stelzer@xray.mpe.mpg.de
Contents
- 1. Introduction
- 2. The ROSAT data
- 3. The X-ray emission from HD 560
- 4. The X-ray flare on HD 560
- 5. Results and conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 2000
Online publication: December 11, 2000
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