Search Publications
A ultraluminous X-ray source associated with a cloud collision in M99
Soria, Roberto; Wong, Diane Sonya
The Sc galaxy M99 in the Virgo Cluster has been strongly affected by tidal interactions and recent close encounters, responsible for an asymmetric spiral pattern and a high star formation rate. Our XMM-Newton study shows that the inner disc is dominated by hot plasma at kT ~ 0.30 keV, with a total X-ray luminosity of ~1041ergs-1
The Serendipitous XMM-Newton Cluster Athens Survey (SEXCLAS): sample selection and the cluster logN-logS
Georgakakis, A.; Georgantopoulos, I.; Plionis, M. +4 more
In this paper we serendipitously identify X-ray cluster candidates using XMM-Newton archival observations complemented by five-band optical photometric follow-up observations (r~ 23 mag) as part of the X-ray Identification (XID) programme. Our sample covers an area of ~2.1 deg2 (15 XMM-Newton fields) and comprises a total of 21 (19 sere…
X-ray spectral variations of U Gem from quiescence to outburst
Göǧüş, E.; Güver, T.; Uluyazı, C. +1 more
In this paper, we report the discovery of a high-energy component of the X-ray spectra of U Gem, which can be observed while the source is in outburst. We used Chandra and XMM-Newton observations to compare the quiescence and outburst X-ray spectra of the source. The additional component may be the result of the reflection of X-rays emitted from a…
Red active galactic nuclei in XMM-Newton/Sloan Digital Sky Survey fields
Georgantopoulos, I.; Akylas, A.; Georgakakis, A. E.
In this paper we combine archival and proprietary XMM-Newton observations (about 5deg2) that overlap with the Sloan Digital Sky Survey to explore the nature of the moderate-z X-ray population. We focus on X-ray sources with optically red colours (g - r > 0.4), which we argue are important for understanding the origin of the X-ray bac…
XMM-Newton discovery of the X-ray transient XMMU J181227.8-181234 in the Galactic plane
Cackett, Edward M.; Wijnands, Rudy; Remillard, Ron
We report the discovery of an X-ray transient, observed in outburst with XMM-Newton on 2003 March 20, and with position (J2000, approximate positional error 2arcsec). No known source is present at this position and the source was not detected during published ROSAT or ASCA observations of that region. However, the source may be associated with 1H1…
The infrared void in the Lupus dark clouds revisited: a polarimetric approach
Franco, G. A. P.; Alves, F. O.
The results of B-band CCD imaging linear polarimetry obtained for stars from the Hipparcos catalogue are used to re-examine the distribution of the local interstellar medium towards the IRAS 100-µm emission void in the Lupus dark clouds. The analysis of the obtained parallax-polarization diagram assigns to the dark cloud Lupus1 a distance be…
X-rays from the radio-quiet quasar PG 1407+265: relativistic jet or accretion disc emission?
Gallo, L. C.
We present two XMM-Newton observations of the luminous (Lx > 1046ergs-1), radio-quiet quasar PG 1407+265, separated by 11 months. The data indicate two distinct states: a highly variable, bright state (first epoch); and a quiescent, low-flux one (second epoch). During the low-flux state the spectrum is consisten…
Properties of dust and detection of Hα emission in LDN 1780
del Burgo, C.; Cambrésy, L.
We present ISOPHOT observations between 60 and 200µm and a near-infrared extinction map of the small intermediate-density cloud Lynds Dark Nebula (LDN) 1780 (Galactic coordinates l = 359° and b = 36.8°). For an angular resolution of 4arcmin, the visual extinction maximum is AV = 4.4mag. We have used the ISOPHOT data together with …
Ultraviolet variability of the magnetic chemically peculiar star 56 Arietis
Sokolov, N. A.
The spectrophotometric variability of the magnetic chemically peculiar star 56 Arietis (56 Ari) in the far-ultraviolet spectral region from 1150 to 1980 Å is investigated. This study is based on the archival International Ultraviolet Explorer data obtained at different phases of the rotational cycle. The brightness of 56 Ari is not constant in the…
Absolute parameters of the Algol binary V505 Sgr from infrared JK light curves
Arévalo, M. J.; Lázaro, C.; Antonopoulou, E.
We present the first light curves of V505 Sgr in the infrared (IR) J and K bands. The light curves are analysed with a code based on Roche geometry and stellar model atmosphere fluxes in order to determine a new set of stellar and orbital parameters. From the visual-IR photometry we find no evidence of IR excess in the system. We study the effect …