Search Publications
XMM–Newton observations of soft gamma-ray repeaters
Mereghetti, Sandro; Esposito, Paolo; Tiengo, Andrea
All the confirmed Soft Gamma-ray Repeaters have been observed with the EPIC instrument on the XMM–Newton satellite. We review the results obtained in these observations, providing the most accurate spectra on the persistent X-ray emission in the 1–10 keV range for these objects, and discuss them in the context of the magnetar interpretation.
Coronal abundances of X-ray bright pre-main sequence stars in the Taurus molecular cloud
Güdel, M.; Micela, G.; Maggio, A. +2 more
Aims:We studied the thermal properties and chemical composition of the X-ray emitting plasma of a sample of bright members of the Taurus Molecular Cloud to investigate possible differences among classical and weak-lined T Tauri stars, and possible dependences of the abundances on the stellar activity level and/or on the presence of accretion/circu…
The Young Stellar Population of NGC 4214 as Observed with the Hubble Space Telescope. I. Data and Methods
Úbeda, Leonardo; MacKenty, John W.; Maíz-Apellániz, Jesús
We present the data and methods that we have used to perform a detailed UV-optical study of the nearby dwarf starburst galaxy NGC 4214 using multifilter Hubble Space Telescope WFPC2 and STIS photometry. We explain the process followed to obtain high-quality photometry and astrometry of the stellar and cluster populations of this galaxy. We describ…
Combining astrometry with the light-time effect: The case of VW Cep, ζ Phe and HT Vir
Wolf, M.; Zasche, P.
Three eclipsing binary systems with astrometric orbit have been studied. For a detailed analysis two circular-orbit binaries (VW Cep and HT Vir) and one binary with an eccentric orbit (ζ Phe) have been chosen. Merging together astrometry and the analysis of the times of minima, one is able to describe the orbit of such a system completely. The O-C…
Outflow or galactic wind: the fate of ionized gas in the halos of dwarf galaxies
Weis, K.; Bomans, D. J.; Dettmar, R. -J. +1 more
Context: Hα images of star bursting irregular galaxies reveal a large amount of extended ionized gas structures, in some cases at kpc-distance away from any place of current star forming activity. A kinematic analysis of especially the faint structures in the halo of dwarf galaxies allows insights into the properties and the origin of this gas com…
Prediction of Space Weather Using an Asymmetric Cone Model for Halo CMEs
Gopalswamy, N.; Michalek, G.; Yashiro, S.
Halo coronal mass ejections (HCMEs) are responsible of the most severe geomagnetic storms. A prediction of their geoeffectiveness and travel time to Earth's vicinity is crucial to forecast space weather. Unfortunately, coronagraphic observations are subjected to projection effects and do not provide true characteristics of CMEs. Recently, Michalek…
Evidence for a high-energy tail associated with foreshock field-aligned beams
RèMe, H.; Lucek, E. A.; Parks, G. K. +4 more
The reduced particle distributions of field-aligned beams observed upstream of the bow shock are examined in detail using Cluster spacecraft. We find that the reduced parallel and perpendicular distribution forms can be strongly geometry-dependent. Above a certain critical value of the angle between the local shock normal and the direction of the …
First Constraints on Rings in the Pluto System
Stern, S. A.; Steffl, A. J.
Simple theoretical calculations have suggested that small-body impacts onto Pluto's newly discovered small satellites, Nix and Hydra, are capable of generating time-variable rings or dust sheets in the Pluto system. Using Hubble Space Telescope ACS data obtained on 2006 February 15 and 2006 March 2, we find no observational evidence for such a rin…
Possible non-thermal nature of the soft-excess emission in the cluster of galaxies Sérsic 159-03
Kaastra, J. S.; Vink, J.; Tamura, T. +3 more
We present an analysis of new Suzaku data and archival data from XMM-Newton of the cluster of galaxies Sérsic 159-03, which has a strong soft X-ray excess emission component. The Suzaku observation confirms the presence of the soft excess emission, but it does not confirm the presence of redshifted O VII lines in the cluster. Radial profiles and 2…
On the location of dayside magnetic reconnection during an interval of duskward oriented IMF
Balogh, A.; Davies, J. A.; Wild, J. A. +7 more
We present space- and ground-based observations of the signatures of magnetic reconnection during an interval of duskward-oriented interplanetary magnetic field on 25 March 2004. In situ field and plasma measurements are drawn from the Double Star and Cluster satellites during traversals of the pre-noon sector dayside magnetopause at low and high …