Search Publications
Automated spectral and timing analysis of AGNs
Guainazzi, M.; Karas, V.; Munz, F.
% We have developed an autonomous script that helps the user to automate the XMM-Newton data analysis for the purposes of extensive statistical investigations. We test this approach by examining X-ray spectra of bright AGNs pre-selected from the public database. The event lists extracted in this process were studied further by constructing their e…
Discovery of a double peaked Fe emission line in the Cloverleaf quasar H 1413+117
Agol, E.; Dai, X.; Chartas, G. +2 more
Our spatial and spectral analysis of a recent deep Chandra observation of H 1413+117 confirms a microlensing event in a previous Chandra observation of this object performed about 5 years earlier. We present constraints on the structure of H 1413+117 based on the time-scale of this microlensing event. The analysis of the combined spectrum of the i…
Absolute magnitudes for late-type dwarf stars for Sloan photometry
Bilir, S.; Karaali, S.; Tunçel, S.
We present a new formula for absolute magnitude determination for late-type dwarf stars as a function of (g-r) and (r-i) for Sloan photometry. The absolute magnitudes estimated by this approach are brighter than those estimated by colour-magnitude diagrams, and they reduce the luminosity function rather close to the luminosity function of Hipparco…
Ultracool dwarf binaries
Bouy, H.; Bouvier, J.; Brandner, W. +1 more
We review here the multiplicity properties of ultracool dwarfs (spectral type later than M6) observed in three different environments and at three different ages: in the field, where the objects are relatively old (1-5 Gyrs) and isolated, in the Pleiades young (∼120 Myr) open cluster, and in the young (∼5 Myr) Upper Scorpius OB association (USco).…
The field of IC 2602: Strömgren-Hβ photometry approach
Kaltcheva, N.; Jaeger, S.; Kaba Bah, M. +1 more
A homogeneous data-base collating all uvbyβ photometry available at present for O-B9 stars in the field of IC 2602 is presented. The characteristics of the field are studied. Four spatially coherent groups can be distinguished. A low reddened compact group located at 156±6 pc is identified with IC 2602, followed by background layers at 546±33 pc, …
Nearby stars of the Galactic disk and halo. III.
Fuhrmann, K.
High-resolution spectroscopic observations of about 150 nearby stars or star systems are presented and discussed. The study of these and another 100 objects of the previous papers of this series implies that the Galaxy became reality 13 or 14 Gyr ago with the implementation of a massive, rotationally-supported population of thick-disk stars. The v…
Astrophysical supplements to the ASCC-2.5. II. Membership probabilities in 520 Galactic open cluster sky areas
Scholz, R. -D.; Piskunov, A. E.; Kharchenko, N. V. +2 more
We present a catalogue (CSOCA ) of stars residing in 520 Galactic open cluster sky areas which is the result of the kinematic (proper motion) and photometric member selection of stars listed in the homogeneous All-sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5). We describe the structure and contents of the catalogue, the selection procedur…
Astrophysical supplements to the ASCC-2.5. I. Radial velocity data
Scholz, R. -D.; Piskunov, A. E.; Kharchenko, N. V.
We present a catalogue of radial velocities of Galactic stars with high precision astrometric data CRVAD which is the result of the cross-identification of star lists from the General Catalog of Average Radial Velocities (GCRV) and from the homogeneous All-sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5). The CRVAD includes accurate J2000 eq…
Probing small scale structure in the atmosphere of V471 Tauri
Walter, F. M.
The white dwarf in the eclipsing binary system V471 Tau is viewed through the atmosphere of the active K star prior to ingress and after egress. In the far UV the surface brightness of the hot white dwarf far outshines the K star emission. We can use this to probe the structure of the extended K star atmosphere along one line of sight, in absorpti…
Doppler Tomography of X-ray binaries
Boroson, B.; Vrtílek, S. D.; Quaintrell, H. +1 more
The Space Telescope Imaging Spectrograph (STIS) on HST provides the first ultraviolet data that are of sufficient spectral and temporal resolution to generate Doppler tomograms of X-ray binaries. We show both optical and ultraviolet maps constructed for the intermediate mass system Hercules X-1/HZ Her and the massive wind-fed system SMC X-1/SK160.…