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An Analysis of Ultraviolet Spectra of Extreme Helium Stars and New Clues to Their Origins
Rao, N. Kameswara; Lambert, David L.; Pandey, Gajendra +1 more
Abundances of about 18 elements including the heavy elements Y and Zr are determined from Hubble Space Telescope Space Telescope Imaging Spectrograph ultraviolet spectra of seven extreme helium stars (EHes): LSE 78, BD +10 2179, V1920 Cyg, HD 124448, PV Tel, LS IV-1 2, and FQ Aqr. New optical spectra of BD +10 2179, V1920 Cyg, and HD 124448 were a…
The build-up of the red sequence in the galaxy cluster MS1054-0321 at z = 0.831
Andreon, S.
Using one of the deepest data sets available, we determine that the red sequence of the massive cluster MS1054-0321 at z = 0.831 is well populated at all studied magnitudes, showing no deficit of faint (down to M* + 3.5) red galaxies: the faint end of the colour-magnitude relation is neither empty nor underpopulated. The effect is quantified by th…
Multi wavelength study of the gravitational lens system RXS J1131-1231. II. Lens model and source reconstruction
Surdej, J.; Riaud, P.; Sluse, D. +1 more
Aims.High angular resolution images of the complex gravitational lens system
…
Flux-Rope Coronal Mass Ejection Geometry and Its Relation to Observed Morphology
St. Cyr, O. C.; Krall, J.
A simple parameterization of a three-dimensional flux rope is used to determine a ``typical flux-rope geometry'' that corresponds to observed flux-rope coronal mass ejection (CME) morphologies (average apparent angular widths) at a leading-edge height of about 5.5 Rsolar. The parameterized flux rope, the curved axis of which is assumed to trace ou…
Hubble Space Telescope Images of Magellanic Cloud Planetary Nebulae
Mutchler, Max; Villaver, Eva; Shaw, Richard A. +1 more
We present images and slitless spectra that were obtained in Hubble Space Telescope (HST) surveys of planetary nebulae (PNe) in both the Large and Small Magellanic Clouds, using the Space Telescope Imaging Spectrograph. These new data on 59 PNe (54 in the LMC and 5 in the SMC) permit us to determine the nebular dimensions and morphology in the mon…
Origins of the Martian aurora observed by Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express
Frahm, R. A.; Leblanc, F.; Halekas, J. S. +6 more
On the 11 August 2004, the UV spectrograph Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express made the first observation of auroral-type emission on the Martian nightside. In this paper, we describe the results of a new analysis of the observed emission owing to a better calibration of SPICAM…
Characteristics of high altitude oxygen ion energization and outflow as observed by Cluster: a statistical study
Lundin, R.; Yamauchi, M.; Sauvaud, J. -A. +14 more
The results of a statistical study of oxygen ion outflow using Cluster data obtained at high altitude above the polar cap is reported. Moment data for both hydrogen ions (H+) and oxygen ions (O+) from 3 years (2001-2003) of spring orbits (January to May) have been used. The altitudes covered were mainly in the range 5-12 R
IGR J16393-4643: a new heavily-obscured X-ray pulsar
Walter, R.; Bird, A. J.; Ubertini, P. +5 more
An analysis of the high-energy emission from IGR J16393-4643 (=AX J1639.0-4642) is presented using data from INTEGRAL and XMM-Newton. The source is persistent in the 20-40 keV band at an average flux of 5.1×10-11 erg cm-2 s-1, with variations in intensity by at least an order of magnitude. A pulse period of 912.0±0…
Electric field measurements on Cluster: comparing the double-probe and electron drift techniques
André, M.; Klecker, B.; Quinn, J. +9 more
The four Cluster satellites each carry two instruments designed for measuring the electric field: a double-probe instrument (EFW) and an electron drift instrument (EDI). We compare data from the two instruments in a representative sample of plasma regions. The complementary merits and weaknesses of the two techniques are illustrated. EDI operation…
XMM-Newton observations of the σ Orionis cluster. II. Spatial and spectral analysis of the full EPIC field
Pallavicini, R.; Franciosini, E.; Sanz-Forcada, J.
We present the results of an XMM-Newton observation of the young (∼ 2{-}4 Myr) cluster around the hot star σ Orionis. In a previous paper we presented the analysis of the RGS spectrum of the central hot star; here we discuss the results of the analysis of the full EPIC field. We have detected 175 X-ray sources, 88 of which have been identified wit…