Search Publications
A search for stellar X-ray sources in the Sagittarius and Carina dwarf galaxies. I. X-ray observations
Ramsay, G.; Wu, K.
ROSAT observations found no convincing evidence for X-ray sources located in local dwarf spheroidal galaxies (dSph). Now with more sensitive instruments on board Chandra and XMM-Newton we can reach fainter luminosity levels. We report on an observation of the Sagittarius (Sgr) dSph made using Chandra and an observation of the Carina (Car) dSph mad…
The globular cluster system of NGC 5846 revisited: colours, sizes and X-ray counterparts
Santiago, B. X.; Pastoriza, M. G.; Chies-Santos, A. L. +1 more
Context.NGC 5846 is a giant elliptical galaxy with a previously well studied globular cluster system (GCS), known to have a bimodal colour distribution with a remarkably high red fraction.
Aims.Here we revisit the central galaxy regions searching for new globular cluster (GC) candidates, and measure magnitudes, colours and sizes for them. We al…
Resonance-enhanced two-photon ionization (RETPI) of Si II and an anomalous, variable intensity of the λ1892 Si III] line in the Weigelt blobs of η Carinae
Johansson, S.; Hartman, H.; Letokhov, V. S.
Context: .The Si III] 1892 Å intercombination line shows an anomalously high intensity in spectra of the radiation-rich Weigelt blobs in the vicinity of Eta Carinae. The line disappears during the 100 days long spectral events occurring every 5.5 years.
Aims: .The aim is to investigate whether resonance-enhanced two-photon ionization (RETPI) i…
Identification of four RXTE Slew Survey sources with nearby luminous active galactic nuclei
Revnivtsev, M.; Sazonov, S.; Churazov, E. +1 more
Based on RXTE scans and observations with the SWIFT/XRT telescope and INTEGRAL observatory, we report the identification of four X-ray sources discovered during the RXTE Slew Survey of the |b|>10° sky with nearby (z∼0.017-0.098) luminous (L2-10~keV∼ 5× 1042-1044 erg s-1) active galactic nuclei. Two of…
Correlated X-ray spectral and timing variability of the Be/X-ray binary V0332+53/BQ Camelopardalis during a type II outburst
Reig, P.; Martínez-Núñez, S.; Reglero, V.
Context: .After more than 15 years of quiescence the Be/X-ray binary V0332+53 underwent a giant outburst in December 2004.Aims.We have investigated the timing properties of the source in correlation with its spectral states as defined by different positions in the colour-colour diagram. Methods.We have used RXTE and INTEGRAL light curves to obtain…
On temperature and abundance effects during an X-ray flare on σ Geminorum
Nordon, R.; Güdel, M.; Behar, E.
We compare quiescent and flare X-ray spectra of the RS CVn binary σ Gem obtained with the Chandra and XMM-Newton grating spectrometers. We find that in addition to an overall 25% flux increase, which can be ascribed to variations in the system's quiescence activity over the 15 months that passed between the observations, there is a hot plasma comp…
Variations of the He II λ1640 line in B0e-B2.5e stars
Smith, M. A.
Using the International Ultraviolet Explorer data archive, we have examined the SWP echellograms of 74 B0-B2.5e stars for statistically significant fluctuations in the He II ("Hα") λ1640 line profile. In this sample we found that the He II line is occasionally variable in 10 stars over short to long timescales. The He II-variable stars discovered …
Curvelet analysis of asteroseismic data. I. Method description and application to simulated sun-like stars
García, R. A.; Starck, J. -L.; Pires, S. +3 more
Context: .The detection and identification of oscillation modes (in terms of their ℓ, m, and successive n) is a great challenge for present and future asteroseismic space missions. "Peak tagging" is an important step in the analysis of these data to provide estimations of stellar oscillation mode parameters, i.e., frequencies, rotation rates, and …
XMM-Newton survey of two upper Scorpius regions
Micela, G.; Peres, G.; Favata, F. +4 more
Aims.We studied X-ray emission from young stars by analyzing the deep XMM-Newton observations of two regions of the Upper Scorpius association with an age of 5 Myr.
Methods: .Based on near infrared and optical photometry we identified 22 Upper Scorpius photometric members among the 224 detected X-ray sources. We derived coronal properties of U…
ESO imaging survey: optical follow-up of 12 selected XMM-Newton fields
Motch, C.; Zaggia, S.; Watson, M. G. +12 more
This paper presents the data recently released for the XMM-Newton/WFI survey carried out as part of the ESO Imaging Survey (EIS) project. The aim of this survey is to provide optical imaging follow-up data in BVRI for identification of serendipitously detected X-ray sources in selected XMM-Newton fields. In this paper, fully calibrated individual …