Search Publications
Thermodynamic fluctuations in solar photospheric three-dimensional convection simulations and observations
Rezaei, R.; Puschmann, K. G.; Moreno-Insertis, F. +2 more
Context. Numerical three-dimensional (3D) radiative (magneto-)hydrodynamical [(M)HD] simulations of solar convection are nowadays used to understand the physical properties of the solar photosphere and convective envelope, and, in particular, to determine the Sun's photospheric chemical abundances. To validate this approach, it is important to che…
Absence of hot gas within the Wolf-Rayet bubble around WR 16
Guerrero, M. A.; Toalá, J. A.
We present the analysis of XMM-Newton archival observations towards the Wolf-Rayet (WR) bubble around WR 16. Despite the closed bubble morphology of this WR nebula, the XMM-Newton observations show no evidence of diffuse emission in its interior as in the similar WR bubbles NGC 6888 and S 308. We use the present observations to estimate a 3-σ uppe…
XMM-Newton and Swift observations of XTE J1743-363
Campana, S.; Israel, G.; Stella, L. +5 more
XTE J1743-363 is a poorly known hard X-ray transient, which displays short and intense flares similar to those observed from supergiant fast X-ray transients. The probable optical counterpart shows spectral properties similar to those of an M8 III giant, thus suggesting that XTE J1743-363 belongs to the class of the symbiotic X-ray binaries class.…
The XMM Deep survey in the CDF-S. V. Iron K lines from active galactic nuclei in the distant Universe
Vignali, C.; Gilli, R.; Ranalli, P. +11 more
Context. X-ray spectroscopy of active galactic nuclei (AGN) offers the opportunity to directly probe the inner regions of the accretion disk. Reflection of the primary continuum on the circumnuclear accreting matter produces features in the X-ray spectrum that help to explore the physics and the geometry of the innermost region, close to the centr…
The color dependent morphology of the post-AGB star HD 161796
Waters, L. B. F. M.; Jeffers, S. V.; Min, M. +3 more
Context. Many protoplanetary nebulae show strong asymmetries in their surrounding shells, pointing to asymmetries during the mass loss phase. Questions concerning the origin and the onset of deviations from spherical symmetry are important for our understanding of the evolution of these objects. Here we focus on the circumstellar shell of the post…
Optical monitoring of extragalactic sources for linking the ICRF and the future Gaia celestial reference frame. I. Variability of ICRF sources
Bouquillon, S.; Lambert, S.; Souchay, J. +8 more
Context. The astrometric mission Gaia of the European Space Agency is scheduled to be launched in 2013. It will provide an astrometric catalog of 500 000 extragalactic sources that could be the basis of a new optical reference frame after the Hipparcos satellite one. On the other hand, the current International Celestial Reference Frame (ICRF) is …
Cold fronts and metal anisotropies in the X-ray cool core of the galaxy cluster Zw 1742+3306
Gastaldello, F.; Ettori, S.; Gaspari, M. +5 more
Context. In recent years, our understanding of the cool cores of galaxy clusters has changed. Once thought to be relatively simple places where gas cools and flows towards the centre, now they are believed to be very dynamic places where heating from the central active galactic nucleus (AGN) and cooling, as inferred from active star formation, mol…
The evolution of the jet from Herbig Ae star HD 163296 from 1999 to 2011
Günther, H. M.; Schneider, P. C.; Li, Z. -Y.
Young A and B stars, the so-called Herbig Ae/Be stars (HAeBe), are surrounded by active accretion disks and drive outflows. We study the jet HH 409, which is launched from the HAeBe star HD 163296, using new and archival observations from Chandra and HST/STIS. In X-rays we can show that the central source is not significantly extended. The approac…
High-precision CoRoT space photometry and fundamental parameter determination of the B2.5V star HD 48977
Auvergne, M.; Baudin, F.; Michel, E. +10 more
We present the CoRoT light curve of the bright B2.5V star HD 48977 observed during a short run of the mission in 2008, as well as a high-resolution spectrum gathered with the HERMES spectrograph at the Mercator telescope. We use several time series analysis tools to explore the nature of the variations in the light curve. We performed a detailed a…
X-ray observations of the Compton-thick Seyfert 2 galaxy, NGC 5643
Bianchi, S.; Guainazzi, M.; Matt, G. +3 more
We present results from a ~55 ks long XMM-Newton observation of the obscured AGN, NGC 5643, performed in July 2009. A previous, shorter (about 10 ks) XMM-Newton observation in February 2003 had left two major issues open, the nature of the hard X-ray emission (Compton-thin vs. Compton-thick) and of the soft X-ray excess (photoionized vs. collision…