X-raying the coronae of HD 155555
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)
- NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
We present an analysis of the high-resolution Chandra observation of the multiple system, HD 155555 (an RS Canum Venaticorum; RS CVn type binary system, HD 155555 AB, and its spatially resolved low-mass companion HD 155555 C). This is an intriguing system that shows properties of both an active pre-main-sequence star and a synchronized (main sequence) binary. We obtain the emission measure distribution, temperature structures, plasma densities, and abundances of this system and compare them with the coronal properties of other young/active stars. HD 155555 AB and HD 155555 C produce copious X-ray emission with log L{sub x} of 30.54 and 29.30, respectively, in the 0.3–6.0 keV energy band. The light curves of individual stars show variability on timescales of a few minutes to hours. We analyze the dispersed spectra and reconstruct the emission measure distribution using spectral line analysis. The resulting elemental abundances exhibit an inverse first ionization potential effect in both cases. An analysis of He-like triplets yields a range of coronal electron densities ∼10{sup 10}–10{sup 13} cm{sup −3}. Since HD 155555 AB is classified as both an RS CVn and a PMS star, we compare our results with those of other slightly older active main-sequence stars and T Tauri stars, which indicate that the coronal properties of HD 155555 AB closely resemble that of an older RS CVn binary rather than a younger PMS star. Our results also suggest that the properties of HD 155555 C are very similar to those of other active M dwarfs.
- OSTI ID:
- 22882632
- Journal Information:
- Astrophysical Journal, Vol. 811, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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