Virtual Observatory based identification of AX J194939+2631 as a new cataclysmic variable

We report the discovery of a new cataclysmic variable (CV) among unidentified objects from the ASCA Galactic Plane Survey made using the Virtual Observatory data mining. First, we identified AX J194939+2631 with IPHAS J194938.39+263149.2, the only prominent H-alpha emitter among 400 sources in a 1 arcmin field of the IPHAS survey, then secured as a single faint X-ray source found in an archival Chandra dataset. Spectroscopic follow-up with the 3.5-m Calar Alto telescope confirmed its classification as a CV, possibly of magnetic nature. Our analysis suggests that AX J194939+2631 is a medium distance system (d ~ 0.6 kpc) containing a late-K or early-M type dwarf as a secondary component and a partially disrupted accretion disc revealed by the double-peaked H-alpha line. However, additional deep observations are needed to confirm our tentative classification of this object as an intermediate polar.Comment: 5 pages, 5 figures, 2 tables, accepted to Astronomy and Astrophysic

Search for and investigation of new stellar clusters using the data from huge stellar catalogues

We present new automatic methods of search for star clusters using the data available in new huge stellar catalogues. Using 2MASS catalogue we have discovered over ten new open clusters in the region of Galaxy anticenter and determined their physical parameters.Comment: Proceedings of the 79th Annual Scientific Meeting of the Astronomische Gesellschaft, Cologne(Germany), September 200

A search for hyperluminous X-ray sources in the XMM-Newton source catalog

We present a new method to identify luminous off-nuclear X-ray sources in the outskirts of galaxies from large public redshift surveys, distinguishing them from foreground and background interlopers. Using the 3XMM-DR5 catalog of X-ray sources and the SDSS DR12 spectroscopic sample of galaxies, with the help of this off-nuclear cross-matching technique, we selected 98 sources with inferred X-ray luminosities in the range $10^{41} < L_{\rm X} < 10^{44}\,{\rm erg\,s}^{-1}$, compatible with hyperluminous X-ray objects (HLX). To validate the method, we verify that it allowed us to recover known HLX candidates such as ESO 243$-$49 HLX$-$1 and M82 X$-$1. From a statistical study, we conservatively estimate that up to $71 \pm 11$ of these sources may be fore- or background sources, statistically leaving at least 16 that are likely to be HLXs, thus providing support for the existence of the HLX population. We identify two good HLX candidates and using other publicly available datasets, in particular the VLA FIRST in radio, UKIDSS in the near-infrared, GALEX in the ultra-violet and CFHT Megacam archive in the optical, we present evidence that these objects are unlikely to be foreground or background X-ray objects of conventional types, e.g. active galactic nuclei, BL Lac objects, Galactic X-ray binaries or nearby stars. However, additional dedicated X-ray and optical observations are needed to confirm their association with the assumed host galaxies and thus secure their HLX classification.Comment: 20 pages, 6 figures, accepted to Ap