2000/12/12 by J. Kerp, Fabian Walter, F. Walter +2
Chemistry · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics (astro-ph) #Diagram #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Galaxy #Interstellar medium #Physics #ROSAT #Spectral line #Spectroscopy and Laser Applications #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0012255
6 pages. To appear in Proc. "X-ray astronomy 2000" (Palermo, September 2000), Eds. R. Giacconi, L. Stella, S. Serio, ASP Conf. Series
arxiv created 2000/12/12 · openalex publication_date 2000/12/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present an X-ray study of the irregular dwarf galaxy Holmberg II based on deep ROSAT PSPC observations. Holmberg II is one of the most famous examples of an irregular dwarf galaxy with a disrupted interstellar medium (ISM): expanding HI holes are present across the entire face of the galaxy. Huge HI cavities of kpc extent are found even outside current starforming regions. We search for faint X-ray sources (stellar end points as well as hot gas), touching the limits of the ROSAT PSPC detector and link the newly detected X-ray sources to features detected in other wavelengths. Using an X-ray hardness ratio color-color diagram we show that it is possible to differentiate between thermal plasma and power-law X-ray spectra, which helps to track down the physical nature of the individual sources.