Röntgenstrahlung from Herbig Ae/Be stars

Thomas Preibisch & Hans Zinnecker

Highlight talk at the international conference Röntgenstrahlung from the Universe Würzburg, September 1995

published in MPE report 263 (eds. H.U. Zimmermann, J. Trümper, & H.W. Yorke), p. 17


Herbig Ae/Be stars are young, pre-main-sequence stars of intermediate mass (2 - 8 M_o). They are the more massive analogs to T Tauri stars, but unlike T Tauri stars they are not believed to be convective, convection being a pre-requisite for sustaining magnetic activity, necessary for coronal heating and thus X-ray emission.

We present ROSAT observations of 30 Ae/Be stars, about half of which were detected as X-ray sources with rather high X-ray luminosities up to 10^32 erg/sec. The X-ray spectra and hardness ratios indicate plasma temperatures of 10^7 K, typical for coronal emission.

The high detection rate of X-ray emission from Ae/Be stars is surprising, if the above reasoning is correct. We discuss several possibilities for the origin of the X-ray emission: Shock interaction of the Ae/Be star stellar wind with remnant circumstellar matter, coronal emission caused by a shear dynamo, and unresolved T Tauri companions.

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