Search Publications
Newly discovered active binaries in the RasTyc sample of stellar X-ray sources. I. Orbital and physical parameters of six new binaries
Freire Ferrero, R.; Guillout, P.; Frasca, A. +3 more
We present the first results from follow-up optical observations, both photometric and spectroscopic, of stellar X-ray sources, selected from the RasTyc sample, resulting from the cross-correlation of ROSAT All-Sky Survey (RASS) and TYCHO catalogues. In particular, we report on the discovery of six late-type binaries, for which we obtained good ra…
XMM-Newton and Chandra measurements of the AGN intrinsic absorption: dependence on luminosity and redshift
Georgakakis, A.; Hatziminaoglou, E.; Georgantopoulos, I. +2 more
We combine bright XMM-Newton data with the Chandra Deep Field South observations to explore the behavior of the intrinsic AGN absorption, as a function of redshift and luminosity. Our sample consists of 359 sources selected in the hard 2-8 keV band, spanning the flux range 6 × 10-16-3 × 10-13 erg~cm-2~s-1
Recovering the star formation rate in the solar neighborhood
Prada Moroni, P. G.; Degl'Innocenti, S.; Cignoni, M. +1 more
Aims.This paper develops a method for obtaining the star formation histories of a mixed, resolved population through the use of color-magnitude diagrams (CMDs). The method provides insight into the local star formation rate, analyzing the observations of the Hipparcos satellite through a comparison with synthetic CMDs computed for different histor…
Observational evidence for a truncation of the star cluster initial mass function at the high mass end
Bastian, N.; Larsen, S. S.; Gieles, M. +3 more
We present the luminosity function (LF) of star clusters in M 51 based on HST/ACS observations taken as part of the Hubble Heritage project. The clusters are selected based on their size and with the resulting 5990 clusters we present one of the largest cluster samples of a single galaxy. We find that the LF can be approximated with a double power…
Multi-wavelength study of coronal waves associated with the CME-flare event of 3 November 2003
Magdalenić, J.; Temmer, M.; Vršnak, B. +4 more
The large flare/CME event that occurred close to the west solar limb on 3 November 2003 launched a large-amplitude large-scale coronal wave that was observed in Hα and Fe xii 195 Å spectral lines, as well as in the soft X-ray and radio wavelength ranges. The wave also excited a complex decimeter-to-hectometer type II radio burst, revealing the for…
Charge-transfer induced EUV and soft X-ray emissions in the heliosphere
Lallement, R.; Izmodenov, V.; Quémerais, E. +4 more
Aims.We study the EUV/soft X-ray emission generated by charge transfer between solar wind heavy ions and interstellar neutral atoms and variations of the X-ray intensities and spectra with the line of sight direction, the observer location, the solar cycle phase and the solar wind anisotropies, and a temporary enhancement of the solar wind similar…
IGR J17544-2619 : a new supergiant fast X-ray transient revealed by optical/infrared observations
Chaty, S.; Negueruela, I.; Pellizza, L. J.
One of the most recent discoveries of the INTEGRAL observatory is the existence of a previously unknown population of X-ray sources in the inner arms of the Galaxy.
Large amplitude oscillation of a polar crown filament in the pre-eruption phase
Isobe, H.; Tripathi, D.
Aims.We report observation of a large-amplitude filament oscillation followed by an eruption. This is used to probe the pre-eruption condition and the trigger mechanism of solar eruptions.Methods.We used the EUV images from the Extreme-Ultraviolet Imaging Telescope on board SOHO satellite and the Hα images from the Flare Monitoring Telescope at Hi…
Structure and scaling of the entropy in nearby galaxy clusters
Arnaud, M.; Pointecouteau, E.; Pratt, G. W.
Using XMM-Newton observations, we investigate the scaling and structural properties of the ICM entropy in a sample of 10 nearby (z < 0.2) morphologically relaxed galaxy clusters in the temperature range 2-9 keV. We derive the local entropy-temperature (S{-}T) relation at R = 0.1, 0.2, 0.3 and 0.5R200. The logarithmic slope of the rel…
The radio structure of radio-quiet quasars
Falcke, H.; Hüttemeister, S.; Leipski, C. +1 more
Aims.We investigate the radio emitting structures of radio-quiet active galactic nuclei with an emphasis on radio-quiet quasars to study their connection to Seyfert galaxies.
Methods: .We present and analyse high-sensitivity VLA radio continuum images of 14 radio-quiet quasars and six Seyfert galaxies.
Results: .Many of the low redshift ra…