Related papers: Soft X-ray emission from the classical nova AT 201…

We have extended our earlier study (Heard & Warwick 2013, Paper I) of the X-ray emission emanating from the central 100 pc x 100 pc region of our Galaxy to an investigation of several features prominent in the soft X-ray (2-4.5 keV) band.…

A Chandra ACIS-S imaging observation of the nearby galaxy M81 (NGC 3031) reveals 9 luminous soft X-ray sources. The local environments, X-ray spectral properties, and X-ray light curves of the sources are presented and discussed in the…

We present the results of soft X-ray studies of the classical nova V2491 Cygni using the Suzaku observatory. On day 29 after outburst, a soft X-ray component with a peak at ~0.5 keV has appeared, which is tantalising evidence for the…

Context. Supersoft X-ray sources (SSSs) are characterised by very low temperatures (< 100 eV). Classical SSSs have bolometric luminosities in the range of 10^36-10^38 erg/s and are modelled with steady nuclear burning of hydrogen on the…

Half a year after its outburst in September 2002, nova V4743 Sgr evolved into the brightest supersoft X-ray source in the sky with a flux maximum around 30A. We calculated grids of synthetic energy distributions (SEDs) based on NLTE model…

Super-soft X-ray sources were established as a heterogeneous class of objects from observations of the Large Magellanic Cloud (LMC). We have searched for new sources of this class in the X-ray images obtained from the XMM-Newton survey of…

We obtained an optical spectrum of a star we identify as the optical counterpart of the M31 Chandra source CXO J004318.8+412016, because of prominent emission lines of the Balmer series, of neutral helium, and a He II line at 4686 Angstrom.…

We report on the hard X-ray burst and the first ~100 days NICER monitoring of the soft X-ray temporal and spectral evolution of the newly-discovered magnetar Swift J1818.0-1607. The burst properties are typical of magnetars with a duration…

Classical novae are runaway thermonuclear burning events on the surfaces of accreting white dwarfs in close binary star systems, sometimes appearing as new naked-eye sources in the night sky. The standard model of novae predicts that their…

The detection of a short hard X-ray burst and an associated bright soft X-ray source by the Swift satellite in 2020 October heralded a new magnetar in outburst, SGR J1830-0645. Pulsations at a period of ~10.4 s were detected in prompt…

KPD 0005+5106, with an effective temperature of $\simeq$200,000 K, is one of the hottest white dwarfs (WDs). ROSAT unexpectedly detected "hard" ($\sim$1 keV) X-rays from this apparently single WD. We have obtained Chandra observations that…

We report the results of a new \textit{XMM-Newton} observation of the helium-rich hot subdwarf BD+37$^{\circ}$442 carried out in February 2016. The possible periodicity at 19 s seen in a 2011 shorter observation is not confirmed, thus…

Classical novae are significant sources of interstellar material, especially carbon, nitrogen and oxygen. These standard candles are only behind supernovae and $\gamma$-ray bursts as the third brightest objects in the sky, and the most…

Classical novae (CNe) have been found to represent the major class of supersoft X-ray sources (SSS) in our neighbour galaxy M 31. We determine properties and evolution of the two first SSSs ever discovered in the M 31 globular cluster (GC)…

Short supersoft X-ray source (SSS) states (durations < 100 days) of classical novae (CNe) indicate massive white dwarfs that are candidate progenitors of supernovae type Ia. We carry out a dedicated optical and X-ray monitoring program of…

We report on the analysis of two XMM-Newton observations of the recently discovered soft gamma repeater Swift J1834.9-0846, taken in September 2005 and one month after the source went into outburst on 2011 August 7. We performed timing and…

We report on a 350-ks NuSTAR observation of the magnetar 1E 1841-045 taken in 2013 September. During the observation, NuSTAR detected six bursts of short duration, with $T_{90}<1$ s. An elevated level of emission tail is detected after the…

Results from a 37,000 s BeppoSAX Low-Energy Concentrator Spectrometer (LECS) observation of the supersoft source SMC 13 (=1E 0035.4-7230) in the Small Magellanic Cloud are reported. The BeppoSAX spectrum is fitted either with a blackbody…

We report on a BeppoSAX Low-Energy Concentrator Spectrometer (LECS) observation of the super-soft source (SSS) CAL83. The X-ray emission in SSS is believed to arise from nuclear burning of accreted material on the surface of a white dwarf…

AstroSat observed transient neutron star low-mass X-ray binary XTE J1701-462 for a total duration of $\sim$ 135 ks during its 2022 outburst. The source traced a complete `Z' shaped structure in the hardness intensity diagram (HID). The…