Abstract Details
| Name: Lalitha Sairam Affiliation: Tata Institute of Fundamental Research Conference ID: ASI2015_696 Title : Outer atmospheres of HD 155555 system Authors and Co-Authors : Singh, K.P., Drake, S., Kashyap, V. Abstract Type : Poster 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 stars with a late-type subgiant or main-sequence companion. We will present our ongoing work on a systematic and detailed study of coronal X-ray emission from a 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 stars. The G (HD 155555 A) and K stars (HD 155555 B) are short period binaries with an orbital period of 1.68 d. The M dwarf companion HD 155555 C is 33$''$ away from the close-in binary system. Both HD~155555~AB and HD~155555~C are strong X-ray sources with log~L$_X$ of 30.54 and 29.30, 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) and consequently obtained the elemental abundances from EMD and examined the FIP effect. From an analysis of He-like triplets of Si XIII, Mg XII and Ne IX, we have derived the coronal electron densities of $\sim$10$^{10}$ cm$^{-3}$. Finally, we compare our results with those of other bright RS CVn types, like, AR Lac and TW Hya, which is slightly older than and younger than HD 155555, respectively. |