Search Publications
Probing the unified model in NGC 7314
Kaastra, J. S.; Costantini, E.; Ebrero, J. +2 more
Aims: We aim at studying the complex absorbed X-ray spectrum of the Narrow Line Seyfert 1 galaxy NGC 7314.
Methods: We collected available public X-ray data from the archives of XMM-Newton, Suzaku, and ASCA. The spectra were analyzed using the fitting package SPEX.
Results: We find evidence of intrinsic neutral and ionized absorptio…
Magnetic helicity balance during a filament eruption that occurred in active region NOAA 9682
Poedts, S.; Romano, P.; Zuccarello, F. P. +1 more
Context. Photospheric shear plasma flows in active regions may be responsible for the magnetic helicity injection in the solar corona not only during the energy storage process before a solar eruption, but also during and after the release of the free magnetic energy caused by the eruption. Indeed, after a filament eruption or expansion the magnet…
4U 1909+07: a well-hidden pearl
Wilms, J.; Pottschmidt, K.; Fürst, F. +4 more
We present the first detailed spectral and timing analysis of the high mass X-ray binary (HMXB) 4U 1909+07 with INTEGRAL and RXTE. 4U 1909+07 is detected in the ISGRI 20-40 keV energy band with an average countrate of 2.6 cts s-1. The pulse period of ~604 s is not stable, but changing erratically on timescales of years. The pulse profil…
The XMM-Newton survey of the Small Magellanic Cloud: discovery of the 11.866 s Be/X-ray binary pulsar XMMU J004814.0-732204(SXP11.87)
Pietsch, W.; Haberl, F.; Hatzidimitriou, D. +12 more
Aims: One of the goals of the XMM-Newton survey of the Small Magellanic Cloud is to study the Be/X-ray binary population. During one of our first survey observations, a bright new transient - XMMU J004814.0-732204 - was discovered.
Methods: We present the analysis of the EPIC X-ray data, together with optical observations, to investigate…
Internal dynamics of the galaxy cluster Abell 545. The ideal case where to study the simultaneous formation of a galaxy system and its brightest galaxy
Rossetti, M.; Eckert, D.; Boschin, W. +3 more
Context. The mechanisms giving rise to diffuse radio emission in galaxy clusters, and in particular their connection with cluster mergers, are still debated.
Aims: We seek to explore the internal dynamics of the cluster Abell 545, which has been shown to host a radio halo. Abell 545 is also peculiar for hosting in its center a very bright, re…
The various contributions in Venus rotation rate and LOD
Souchay, J.; Lebonnois, S.; Rambaux, N. +1 more
Context. Thanks to the Venus Express Mission, new data on the properties of Venus could be obtained, in particular concerning its rotation.
Aims: In view of these upcoming results, the purpose of this paper is to determine and compare the major physical processes influencing the rotation of Venus and, more particularly, the angular rotation r…
Hubble Space Telescope study of resolved red giant stars in the outer halos of nearby dwarf starburst galaxies
van der Marel, R. P.; Aloisi, A.; Annibali, F. +2 more
Context. Central starbursts in galaxies are an extreme example of ongoing galaxy evolution. The outer parts of galaxies contain a fossil record of galaxy formation and evolution processes in the more distant past. The characterization of resolved stellar populations allows one a detailed study of these topics.
Aims: We observed the outer part…
Distinguishing post-AGB impostors in a sample of pre-main sequence stars
Vieira, R. G.; Szczerba, R.; Stasińska, G. +2 more
Context. A sample of 27 sources, cataloged as pre-main sequence stars by the Pico dos Dias Survey (PDS), is analyzed to investigate a possible contamination by post-AGB stars. The far-infrared excess due to dust present in the circumstellar envelope is typical of both categories: young stars and objects that have already left the main sequence and…
Distances and stellar population properties for 12 elliptical galaxies
Cantiello, M.; Capaccioli, M.; Brocato, E.
Aims: We use the surface brightness fluctuation (SBF) technique to derive the distances and analyse the radial behaviour of stellar populations in a sample of 12 elliptical galaxies. The data are I-band images collected with the FORS1 camera at the Very Large Telescope (VLT), drawn from the ESO archive. The main purpose of our analysis is to …
Quasi-periodic flares in EXO 2030+375 observed with INTEGRAL
Klochkov, D.; Santangelo, A.; Ferrigno, C. +5 more
Context. Episodic flaring activity is a common feature of X-ray pulsars in HMXBs. In some Be/X-ray binaries flares were observed in quiescence or prior to outbursts. EXO 2030+375 is a Be/X-ray binary showing "normal" outbursts almost every ~46 days, near periastron passage of the orbital revolution. Some of these outbursts were occasionally monito…