EDP Sciences
Free Access
Volume 373, Number 2, July II 2001
Page(s) 438 - 446
Section Extragalactic astronomy
DOI https://doi.org/10.1051/0004-6361:20010595

A&A 373, 438-446 (2001)
DOI: 10.1051/0004-6361:20010595

The X-ray view of M 33 after ROSAT

F. Haberl and W. Pietsch

Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany

(Received 28 February 2001 / Accepted 14 April 2001 )

We present a catalogue of 184 X-ray sources within 50´of the nucleus of the local group spiral galaxy M 33. The catalogue is derived from an analysis of the complete set of ROSAT archival data pointed in the direction of M 33 and contains X-ray position, existence likelihood, count rates and PSPC spectral hardness ratios. To identify the sources the catalog was correlated with previous X-ray catalogues, optical and radio catalogues. In addition sources were classified according to their X-ray properties. We find seven candidates for supersoft X-ray sources, of which two may be associated with known planetary nebulae in M 33. The majority of X-ray detected supernova remnants is also detected at radio frequencies and seen in optical lines. The low overall X-ray detection rate of optically selected SNRs can probably be attributed to their expansion into interstellar matter of low density.

Key words: galaxies: individual: Messier 33 -- galaxies: stellar content -- stars: variables: general -- X-rays: stars -- catalogs

Offprint request: F. Haberl, fwh@mpe.mpg.de

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