Search Publications
On the stability of clathrate hydrates in comets 67P/Churyumov-Gerasimenko and 46P/Wirtanen
Weaver, H. A.; Mousis, O.; Schmitt, B. +3 more
Context. For several years, Jupiter-family comets have been the targets of spacecraft missions whose aims are to determine the comets' composition, structure, and physical properties. The Rosetta mission is currently flying towards comet 67P/Churyumov Gerasimenko for a rendezvous in August 2014 and comet 46P/Wirtanen is considered for a rendezvous…
Supernovae without host galaxies?. Hypervelocity stars in foreign galaxies
Bomans, D. J.; Zinn, P. -C.; Grunden, P.
Context. Harvesting the SAI supernova catalog, the most complete list of supernovae (SNe) currently available, we search for SNe that apparently do not occur within a distinct host galaxy but lie a great distance (several arcmin) apart from the host galaxy given in the catalog or even show no sign of an identifiable galaxy in their direct vicinity…
Is CGCS 5926 a symbiotic X-ray binary?
Masetti, N.; Munari, U.; Osborne, J. P. +3 more
We report on multiwavelength (X-ray to optical) follow-up observations of the carbon star CGCS 5926. These were motivated by the fact that this star is positionally coincident with a faint X-ray emitting object belonging to the ROSAT catalog of sources, thus suggesting a possible symbiotic X-ray binary (SyXB) nature for it. Our spectrophotometric …
Multiwavelength campaign on Mrk 509. VII. Relative abundances of the warm absorber
Kaastra, J. S.; Kriss, G. A.; Arav, N. +14 more
Context. The study of abundances in the nucleus of active galaxies allows us to investigate the evolution of the abundance by comparing local and higher redshift galaxies. However, the methods used so far have substantial drawbacks or rather large uncertainties. Some of the measurements are at odds with the initial mass function derived from the o…
Iron abundance in the prototype PG 1159 star, GW Vir pulsator PG 1159 - 035, and related objects
Rauch, T.; Werner, K.; Kruk, J. W. +1 more
We performed an iron abundance determination of the hot, hydrogen deficient post-AGB star PG 1159 - 035, which is the prototype of the PG 1159 spectral class and the GW Vir pulsators, and of two related objects (PG 1520 + 525, PG 1144 + 005), based on the first detection of Fe viii lines in stellar photospheres. In another PG 1159 star, PG 1424 + …
A multi-wavelength study of the unidentified TeV gamma-ray source HESS J1626-490
Rolland, L.; Rowell, G.; Stegmann, C. +3 more
Aims: To explore the nature of the unidentified very-high-energy (VHE, E>100 GeV) gamma-ray source HESS J1626-490, we investigated the region in X-ray, sub-millimeter, and infrared energy bands.
Methods: So far only detected with the HESS array of imaging atmospheric Cherenkov telescopes, HESS J1626-490 could not be unambiguously iden…
On the driver of relativistic effect strength in Seyfert galaxies
Bianchi, S.; Guainazzi, M.; Longinotti, A. L. +2 more
Context. Spectroscopy of X-ray emission lines emitted from accretion discs around supermassive black holes is one of the most powerful probes of the accretion flow physics and geometry, while also providing in principle observational constraints on the black hole spin. Previous studies have suggested that relativistically broadened line profiles a…
An X-ray underluminous cluster of galaxies in the 4Ms CDFS observations
Fiore, F.; Castellano, M.; Pentericci, L. +8 more
Aims: We investigate the properties of cluster ClG 0332-2747 at z = 0.734 in the GOODS-South field, which was undetected in the Chandra 2Ms observations. We explore possible scenarios to explain the discrepancy between its low X-ray emission and that expected from the M - LX relation.
Methods: We use the large public spectrosc…
HD 144432: A young triple system
Carmona, A.; Henning, Th.; van Boekel, R. +3 more
We present new imaging and spectroscopic data of the young Herbig star HD 144432 A, which is a well-known binary star with a separation of 1.47″. High-resolution NIR imaging data obtained with NACO at the VLT reveal that HD 144432 B itself is a close binary pair with a separation of 0.1″. High-resolution optical spectra, acquired with FEROS at the…
XMM-Newton observations of the pre-polar HS0922+1333
Schwope, A. D.; Schwarz, R.; Vogel, J.
We report on XMM-Newton and accompanying phase-resolved optical observations of HS0922+1333, one out of nine pre-polars. It shows X-ray and UV variability correlated with the visibility of the main accretion spot. The spectral X-ray properties reveal a low temperature thermal plasma of ~1 keV with FX more than one order of magnitude bel…