X-Ray Coronae from Stars

Abstract

A number of major advances in stellar coronal physics have occurred since 1990 mainly as a consequence of imaging observations by ROSAT and spectroscopic observations by ASCA. These can be summarised as follows:

• 1. an all-sky survey has been performed by ROSAT at a sensitivity of ∼2 x 10⁻¹³ erg cm^2212;2 s^2212;1, complemented by pointed observations an order of magnitude deeper;

• 2. complete mapping and deeper pointings have been obtained for virtually all open clusters closer than ∼ 500 pc, and covering the age range from ∼ 30 Myr to ∼ 700 Myr;

• 3. complete mapping and deeper pointings have been obtained for several Star Forming Regions (SFRs) covering the age range ∼ 1 to ∼ 10 Myr;

• 4. spectroscopic observations of bright coronal sources have been obtained with EUVE and ASCA allowing the derivation of the temperature structure and elemental abundances.