Abstract Details
| Name: Lalitha Sairam Affiliation: Indian Institute of Astrophysics Conference ID: ASI2016_925 Title : Magnetic activities in the outer atmospheres of RS CVn-type Binaries Authors and Co-Authors : Singh, K.P., Tata Institute of Fundamental Research Drake, S. A., NASA Goddard Space Flight Center Kashyap, V., Harvard-Smithsonian Center for Astrophysics Abstract Type : Oral Abstract Category : Stars, The Milky Way Galaxy and its neighbours Abstract : The RS CVn binaries are a class of tidally locked, rapidly rotating close binaries typically composed of a chromospherically active G- or K-type star with a late-type subgiant or main-sequence companion. In my talk, I will present our results from a systematic and detailed study of coronal X-ray emission from the bright young pre-main-sequence RS CVn system -- HD 155555, using Chandra HETG/MEG gratings. This system is a triple star system composed of a G5 IV, K0 IV and M3V star. The G (HD 155555 A) and K stars (HD 155555 B) form a short-period binary system with an orbital period of 1.68 days, that has an M dwarf companion HD 155555 C 33'' away. Both HD 155555 AB and HD 155555 C are strong X-ray sources with log LX of 30.54 and 29.30 ergs/s, respectively. We have analysed the dispersed spectra of both HD 155555 AB and HD 155555 C using discrete temperature APEC models, and have constructed the emission measure distribution (EMD) using spectral line analysis (using the ATOMDB 2.0), We have also obtained the elemental abundances and discuss whether or not they exhibit the Inverse FIP effect typically seen in active stars. From an analysis of the He-like triplets of Si XIII, Mg XII and Ne IX, we have derived coronal electron densities of ~10E10 cm^-3. Finally, we compare our results for HD 155555 with those of other RS CVn systems, such as AR Lac, a much older binary system, and with TW Hya, which is a relatively younger single pre-main sequence star. |