Search Publications
XMM-Newton observations of AM CVn binaries: V396 Hya and SDSS J1240-01
Groot, P. J.; Ramsay, G.; Hakala, P. +3 more
We present the results of XMM-Newton observations of two AM CVn systems - V396 Hya and SDSS J1240-01. Both systems are detected in X-rays and in the UV: neither shows coherent variability in their light curves. We compare the rms variability of the X-ray and UV power spectra of these sources with other AM CVn systems. Apart from ES Cet, AM CVn sou…
Analysis of IUE spectra of helium-rich white dwarf stars
Kepler, S. O.; Handler, G.; Koester, D. +1 more
We studied the class of DB white dwarf stars, using re-calibrated UV spectra for thirty four DBs obtained with the IUE satellite. By comparing the observed energy distributions with model atmospheres, we simultaneously determine spectroscopic distances (d), effective temperature (Teff), and surface gravities (log g). Using parallax meas…
Prospects for dark energy evolution: a frequentist multi-probe approach
Yvon, D.; Tao, C.; Tilquin, A. +4 more
A major quest in cosmology is to understand the nature of dark energy. It is now well known that the use of several cosmological probes is required to break the underlying degeneracies on cosmological parameters. In this paper, we present a method based on a frequentist approach that combines probes without any prior constraints. As one applicatio…
The XMM-Newton view of GRS 1915+105
Belloni, T.; Ponti, G.; Matt, G. +3 more
Two XMM-Newton observations of the black-hole binary GRS 1915+105 were triggered in 2004 (April 17 and 21), during a long "plateau" state of the source. We analyzed the data collected with EPIC-pn in timing and burst modes, respectively. Reflection Grating Spectrometers were used only on April 21st. The source 2-10 keV flux is 0.6 (unabsorbed: 0.9…
The XMM-Newton view of the Crab
Freyberg, M. J.; Wilms, J.; Kendziorra, E. +7 more
Aims.We discuss the current X-ray view of the Crab Nebula and Pulsar, summarising our analysis of observations of the source with the EPIC-pn camera on board the XMM-Newton observatory. Different modes of EPIC-pn were combined in order to yield a complete scenario of the spectral properties of the Crab resolved in space and time (pulse phase). In …
UIR bands in the ISO SWS spectrum of the carbon star TU Tauri
Hony, S.; Tielens, A. G. G. M.; Boersma, C.
Polycyclic Aromatic Hydrocarbon (PAH) molecules are thought to form in the ejecta of carbon-rich Asymptotic Giant Branch (AGB) stars. Fifty ISO SWS spectra of warm carbon-rich AGB stars have been investigated for the Unidentified IR (UIR) emission due to fluorescence by PAH molecules. In this sample the binary star TU Tau, which has a blue compani…
Evidence for colliding winds in WR 25 from XMM-Newton observations of X-ray variability
Corcoran, M. F.; Pollock, A. M. T.
The Wolf-Rayet star WR 25 in the Carina Nebula is a surprisingly bright X-ray source, and amongst the brightest WR stars in X-rays. It is a suspected binary star, though its binary nature has been a matter of controversy. We report here observations of WR 25 from the XMM-Newton archive which showed an increase in X-ray luminosity of more than a fa…
Exploring the lower mass function in the young open cluster IC 4665
James, D. J.; Testi, L.; Palla, F. +8 more
We present a study of the young (30-100 Myr) open cluster IC 4665 with the aim to determine the shape of the mass function well into the brown dwarf regime. We photometrically select 691 low-mass stellar and 94 brown dwarf candidate members over an area of 3.82 square degrees centred on the cluster. K-band follow-up photometry and Two-Micron All-S…
INTEGRAL and RXTE monitoring of GRS 1758-258 in 2003 and 2004. A transition from the dim soft state to the hard state
Pottschmidt, K.; Zdziarski, A. A.; Lubiński, P. +3 more
The Galactic Center black hole candidate (BHC)
The ratio of N(C18O) and AV in Chamaeleon I and III-B. Using 2MASS and SEST
Kainulainen, J.; Harju, J.; Lehtinen, K.
We investigate the relationship between the C18O column density and the visual extinction in