We report on the analysis of the Chandra-ACIS data of O, B, and WR stars in the young association Cyg OB2. X-ray spectra of 49 O-stars, 54 B-stars, and 3 WR...
X-ray emission from RX J1720.1+2638 and Abell 267: A comparison between a fossil and a non-fossil system
We present the XMM-Newton X-ray analysis of RX J1720.1+2638 and Abell 267, a non-fossil and a fossil system, respectively. The whole spectrum of both objects...
X-Ray Evidence for a Pole-dominated Corona on AB Dor
A fine analysis of spectral line widths and Doppler shifts employing Fourier transform and cross-correlation techniques has been applied to Chandra HETG spectra...
We present results from two Chandra imaging observations of Ross 154, a nearby flaring M dwarf star. During a 61 ks ACIS-S exposure, a very large flare occurred...
X-ray flashes or soft gamma-ray bursts?. The case of the likely distant XRF 040912
Context: The origin of X-ray Flashes (XRFs) is still a mystery and several models have been proposed. To disentangle among these models, an important...
X-ray long-term variations in the low-luminosity AGN NGC 835 and its circumnuclear emission
Context. Obscured active galactic nuclei (AGNs) are thought to be very common in the Universe. Observations and surveys have shown that the number of sources...
X-ray luminosity functions of different morphological and X-ray type AGN populations
Luminosity functions are one of the most important observational clues when studying galaxy evolution over cosmic time. In this paper we present the X-ray...
X-ray monitoring of classical novae in the central region of M 31. I. June 2006-March 2007
Context. Classical novae (CNe) have recently been reported to represent the major class of supersoft X-ray sources (SSSs) in the central region of our neighbour...
X-ray monitoring of optical novae in M 31 from July 2004 to February 2005
Context: Optical novae have recently been identified as the major class of supersoft X-ray sources in M 31 based on ROSAT and early XMM-Newton and Chandra...