Search Publications
Distances of the bulge globular clusters Terzan 5, Liller 1, UKS 1, and Terzan 4 based on HST NICMOS photometry
Zoccali, M.; Bica, E.; Barbuy, B. +2 more
Context: A large number of pulsars and X-rays sources are detected in globular clusters. To understand the structure and content of these clusters, accurate distances are required.
Aims: We derive the distances of Terzan 5, Liller 1 and UKS 1 using as a reference a recent distance determination of NGC 6528, based on HST/NICMOS and NTT/SOFI inf…
Physical parameters of 15 intermediate-age LMC clusters from modelling of HST colour-magnitude diagrams
Santiago, B. X.; Brocato, E.; Kerber, L. O.
Aims:We analyzed HST/WFPC2 colour-magnitude diagrams (CMDs) of 15 populous Large Magellanic Cloud (LMC) stellar clusters with ages between ~0.3 Gyr and ~3 Gyr. These (V, B-V) CMDs are photometrically homogeneous and typically reach V ∼ 22. Accurate and self-consistent physical parameters (age, metallicity, distance modulus and reddening) were extr…
Direct constraint on the distance of γ2 Velorum from AMBER/VLTI observations
Beckmann, U.; Marconi, A.; Testi, L. +99 more
Context: Interferometry can provide spatially resolved observations of massive star binary systems and their colliding winds, which thus far have been studied mostly with spatially unresolved observations.
Aims: We present the first AMBER/VLTI observations, taken at orbital phase 0.32, of the Wolf-Rayet and O (WR+O) star binary system
The XMM-Newton serendipitous survey. III. The AXIS X-ray source counts and angular clustering
Bauer, F. E.; Ebrero, J.; Page, M. J. +14 more
Context: Recent results have revised upwards the total X-ray background (XRB) intensity below ~10 keV, therefore an accurate determination of the source counts is needed. There are also contradictory results on the clustering of X-ray selected sources.
Aims: We have studied the X-ray source counts in four energy bands: soft (0.5-2 keV), hard (…
The variable X-ray spectrum of Markarian 766. II. Time-resolved spectroscopy
Turner, T. J.; Kraemer, S. B.; Reeves, J. N. +1 more
Context: The variable X-ray spectra of AGN systematically show steep power-law high states and hard-spectrum low states. The hard, low state has previously been found to be a component with only weak variability. The origin of this component and the relative importance of effects such as absorption and relativistic blurring are currently not clear…
Scaling relations and mass calibration of the X-ray luminous galaxy clusters at redshift ~0.2: XMM-Newton observations
Zhang, Y. -Y.; Finoguenov, A.; Böhringer, H. +4 more
We present the X-ray properties and scaling relations of a flux-limited morphology-unbiased sample of 12 X-ray luminous galaxy clusters at redshift around 0.2 based on XMM-Newton observations. The scaled radial profiles are characterized by a self-similar behavior at radii outside the cluster cores (>0.2 r500) for the temperature (T∝…
Arcfinder: an algorithm for the automatic detection of gravitational arcs
Seidel, G.; Bartelmann, M.
We present an efficient algorithm designed for and capable of detecting elongated, thin features such as lines and curves in astronomical images, and its application to the automatic detection of gravitational arcs. The algorithm is sufficiently robust to detect such features even if their surface brightness is near the pixel noise in the image, y…
Physical properties of z ~ 4 LBGs: differences between galaxies with and without Lyα emission
Pentericci, L.; Santini, P.; Fontana, A. +5 more
Aims:We analysed the physical properties of z ∼4 Lyman Break Galaxies observed in the GOODS-S survey, in order to investigate possible differences between galaxies where the Lyα is present in emission, and those where the line is absent or in absorption.
Methods: The objects were selected from their optical color and then spectroscopically con…
A search for counterparts to massive X-ray binaries using photometric catalogues
Negueruela, I.; Schurch, M. P. E.
Context: The X-ray and γ-ray observatory INTEGRAL has discovered large numbers of new hard X-ray sources, many of which are believed to be high mass X-ray binaries. However, for a significant fraction, their counterparts remain unidentified.
Aims: We explore the use of photometric catalogues to find optical counterparts to high mass X-ray bina…
The X-ray soft excess in classical T Tauri stars
Güdel, M.; Telleschi, A.
Aims:We study an anomaly in the X-ray flux (or luminosity) ratio between the O vii λλ21.6-22.1 triplet and the O viii Lyα line seen in classical T Tauri stars (CTTS). This ratio is unusually high when compared with ratios for main-sequence and non-accreting T Tauri stars (Telleschi et al. 2007c, A&A, 468, 443). We compare these samples to iden…