2009A&A...505..755R

I present the analysis of the X-ray spectrum of the classical TTauri star TW Hydrae, and determine emission measure distributions, elemental abundances, electron temperatures, densities, and line fluxes. TW Hya was observed in the wavelength range 5-175Å by CHANDRA-LETGS. I performed a multi-temperature fit, based on a collisional ionisation equilibrium (CIE) model for optically thin plasmas. I measured line fluxes by fitting a Gaussian line profile, folded through the response matrix, to the observed line features and I applied these values to establish plasma properties. No line features were established in the spectrum above 40Å. Due to the absence of line features above 40Å N_H is calculated to be somewhat higher than assumed so far. The observed ``coronal'' temperature covers a range from about 1.5 to 20MK. The abundance pattern shows a very strong enhancement of Ne and some enhancement of N. From forbidden-intercombination line ratios of OVII and of NeIX I obtain a value for the electron density of n_e≃10¹²cm^–3. This is higher than the value for electron densities in coronal plasmas of older late type main-sequence stars. A blackbody component was added to describe the shape of the continuum around 15Å better. The emitted X-ray luminosity is in the order of 10³⁰erg/s.