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X-Ray Localization of the Globular Cluster G1 with XMM-Newton
Kong, Albert K. H.
We present an accurate X-ray position of the massive globular cluster G1 obtained using XMM-Newton and the Hubble Space Telescope (HST). The X-ray emission of G1 has been detected recently with XMM-Newton. There are two possibilities for the origin of the X-ray emission: it could be due to either accretion of the central intermediate-mass black ho…
Long term hard X-ray variability of the anomalous X-ray pulsar 1RXS J170849.0-400910 discovered with INTEGRAL
Tiengo, A.; Götz, D.; Mereghetti, S. +6 more
Aims:We report on a multi-band high-energy observing campaign aimed at studying the long term spectral variability of the Anomalous X-ray Pulsar (AXP) 1RXS J170849.0-400910, one of the magnetar candidates.
Methods: We observed 1RXS J170849.0-400910 in Fall 2006 and Spring 2007 simultaneously with Swift/XRT, in the 0.1-10 keV energy range, and …
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…