Low-Mass Pre-Main Sequence Stars and Their X-ray Emission
Ralph Neuhäuser
To investigate the formation and early evolution of stars,
astronomers study the x-ray emission of T Tauri stars, which are young,
solar-mass stars called pre-main sequence stars. Two
Earth-orbiting x-ray satellites, the Röntgen X-ray Satellite
(ROSAT) and the Advanced Satellite for Cosmology and
Astrophysics (ASCA), have discovered x-ray emission from young
protostars, called Class I objects. Many T Tauri stars were detected as
x-ray sources by ROSAT. X-ray luminosity functions and correlations
with other stellar parameters can be studied and used to investigate
the x-ray emission mechanism. From the ROSAT data hundreds of T Tauri stars have been discovered, some of which are located outside regions
of ongoing star formation. Stellar x-rays also irradiate circumstellar
disks, regions where planets may form, so x-ray emission data from T
Tauri stars may also be used to investigate the formation of planets.
Max-Planck-Institut für extraterrestrische Physik,
D-85740 Garching, Germany. E-mail: rne{at}mpe-garching.mpg.de
