Hard X-ray emission from a young massive star-forming cluster*
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2 Radioastronomisches Institut der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
Corresponding author: H. Beuther, firstname.lastname@example.org
Accepted: 27 August 2002
We report the detection of hard X-ray emission (>2 keV) from a number of point sources associated with the very young massive star-forming region IRAS 19410+2336. The X-ray emission is detected from several sources located around the central and most deeply embedded mm continuum source, which remains undetected in the X-ray regime. All X-ray sources have K-band counterparts, and those likely belonging to the evolving massive cluster show near-infrared colors in the 2MASS data indicative of pre-main-sequence stages. The X-ray luminosities around 1031 erg s-1 are at the upper end of luminosities known for low-mass pre-main-sequence sources, and mass estimates based on the infrared data indicate that at least some of the X-ray detected sources are intermediate-mass objects. Therefore, we conclude that the X-ray emission is due to intermediate-mass pre-main-sequence Herbig Ae/Be stars or their precursors. The emission process is possibly due to magnetic star-disk interaction as proposed for their low-mass counterparts.
Key words: accretion, accretion disks / stars: early type / stars: formation / ISM: dust, extinction / radiation mechanisms: thermal
Based on observations with the Chandra X-ray observatory, the Calar Alto 3.5 m telescope and the IRAM Plateau de Bure Interferometer. Chandra is operated by the NASA and the CXC, Calar Alto by the Max-Planck-Institut for Astronomy in Heidelberg, jointly with the Spanish National Commission for Astronomy, and IRAM is supported by INSU/CNRS (France, MPG (Germany), and IGN (Spain).
© ESO, 2002