Its combination of good spatial resolution and soft X-ray sensitivity make Chandra an ideal instrument for the detection of luminous supersoft X-ray sources (SSSs)in external galaxies. M31 may provide the best opportunity to study a galactic population of SSSs. We have recently completed a survey of ~ 2560 square arcmin ( ~ 131 kpc^2) of M31

We report very intense and variable Hα emission (pseudoequivalent widths of ~180 and 410 Å) of S Ori 55, a probable free-floating, M9-type substellar member of the young σ Orionis open star cluster. After comparison with state-of-the-art evolutionary models, we infer that S Ori 55 is near or below the cluster deuterium-burning mass borderline

A new method is developed to calculate the amplitude of the galactic warps generated by a torque due to external forces. This takes into account that the warp is produced as a reorientation of the different rings which constitute the disc in order to compensate the differential precession generated by the external force, yielding a uniform

We analyze very deep X-ray and mid-IR surveys in common areas of the Lockman Hole and the Hubble Deep Field-North (HDF-N) to study the sources of the X-ray background (XRB) and to test the standard obscured accretion paradigm. Observations with XMM-Newton and Infrared Space Observatory (ISO) of a substantial area in Lockman are particularly

Thanks to dedicated X-ray monitoring observations of the Galactic bulge with the Wide Field Cameras on BeppoSAX, several tens of faint X-ray transients have been discovered with peak fluxes that are just a few percent of that of classical X-ray novae. Most of these faint transients exhibit type-I X-ray bursts and, thus, harbor a neutron star. A few

M31 is one of the best studied galaxies. At a distance of 700 kpc, it provides us with an opportunity to study the global properties of a galaxy which is similar to our Milky Way. We present our Chandra ACIS observations in the central region and along the disk of M31. We include the following. 1) X-ray spectra of point sources: the energy spectrum