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Astrophysical parameters of Galactic open clusters
Scholz, R. -D.; Piskunov, A. E.; Kharchenko, N. V. +2 more
We present a catalogue of astrophysical data for 520 Galactic open clusters. These are the clusters for which at least three most probable members (18 on average) could be identified in the ASCC-2.5, a catalogue of stars based on the Tycho-2 observations from the Hipparcos mission. We applied homogeneous methods and algorithms to determine angular…
The XMM-Newton view of PG quasars. I. X-ray continuum and absorption
Guainazzi, M.; Schartel, N.; Rodríguez-Pascual, P. M. +3 more
We present results of a systematic analysis of the XMM-Newton spectra of 40 quasars (QSOs) (z≤1.72) from the Palomar-Green (PG) Bright Quasar Survey sample (MB<-23). The sample includes 35 radio-quiet quasars (RQQs) and 5 radio-loud quasars (RLQs). The analysis of the spectra above 2 keV reveals that the hard X-ray continuum emission…
Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
Luri, X.; Jorissen, A.; Turon, C. +4 more
The availability of the Hipparcos Catalogue has triggered many kinematic and dynamical studies of the solar neighbourhood. Nevertheless, those studies generally lacked the third component of the space velocities, i.e., the radial velocities. This work presents the kinematic analysis of 5952 K and 739 M giants in the solar neighbourhood which inclu…
Discovery of the binary pulsar PSR B1259-63 in very-high-energy gamma rays around periastron with HESS
Raux, J.; Ripken, J.; Funk, S. +99 more
We report the discovery of very-high-energy (VHE) γ-ray emission of the binary system
The structural and scaling properties of nearby galaxy clusters. II. The M-T relation
Arnaud, M.; Pointecouteau, E.; Pratt, G. W.
Using a sample of ten nearby (z≲ 0.15), relaxed galaxy clusters in the temperature range [2-9]~keV, we have investigated the scaling relation between the mass at various density contrasts (δ=2500,1000,500,200) and the cluster temperature. The masses are derived from NFW-type model fits to mass profiles, obtained under the hydrostatic assumption us…
The nature and origin of Seyfert warm absorbers
Page, M. J.; Branduardi-Raymont, G.; Blustin, A. J. +2 more
We collate the results of recent high resolution X-ray spectroscopic observations of 23 AGN, and use the resulting information to try to provide answers to some of the main open questions about warm absorbers: where do they originate, what effect do they have on their host galaxies, and what is their importance within the energetics and dynamics o…
The all-sky distribution of 511 keV electron-positron annihilation emission
Knödlseder, J.; Schanne, S.; Schönfelder, V. +11 more
We present a map of 511 keV electron-positron annihilation emission, based on data accumulated with the SPI spectrometer aboard ESA's INTEGRAL gamma-ray observatory, that covers approximately ~95% of the celestial sphere. Within the exposed sky area, 511 keV line emission is significantly detected towards the galactic bulge region and, at a very l…
Cosmological parameters from supernova observations: A critical comparison of three data sets
Choudhury, T. R.; Padmanabhan, T.
We extend our previous analysis of cosmological supernova type Ia data \cite{pc03} to include three recent compilation of data sets. Our analysis ignores the possible correlations and systematic effects present in the data and concentrates mostly on some key theoretical issues. Among the three data sets, the first set consists of 194 points obtain…
A simple test for periodic signals in red noise
Vaughan, S.
We demonstrate a simple method for testing the significance of peaks in the periodogram of red noise data. The procedure was designed to test for spurious periodicities in X-ray light curves of active galaxies, but can be used quite generally to test for periodic components against a background noise spectrum assumed to have a power law shape. The…
Lower mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
Bouret, J. -C.; Hillier, D. J.; Lanz, T.
We have analyzed the far-ultraviolet spectrum of two Galactic O4 stars, the O4If+ supergiant HD 190429A and the O4V((f)) dwarf HD 96715, using archival FUSE and IUE data. We have conducted a quantitative analysis using the two NLTE model atmosphere and wind codes, tlusty and cmfgen, which incorporate a detailed treatment of NLTE metal line blanket…