Search Publications
X-ray observations of Be/X-ray binaries in the SMC
Pietsch, W.; Haberl, F.
Fifteen Be/X-ray binaries and candidates in the SMC were observed serendipitously with the EPIC instruments of XMM-Newton during two observations of SNR 0047-73.5 and SNR 0103-72.6 in October 2000. A total of twelve of those sources are detected. For eleven of them an accurate position and in part detection of X-ray pulsations support the proposed…
A distance of 133-137 parsecs to the Pleiades star cluster
Kulkarni, S. R.; Shao, M.; Pan, Xiaopei
Nearby `open' clusters of stars (those that are not gravitationally bound) have played a crucial role in the development of stellar astronomy because, as a consequence of the stars having a common age, they provide excellent natural laboratories to test theoretical stellar models. Clusters also play a fundamental part in determining distance scale…
A multiply imaged, submillimetre-selected ultraluminous infrared galaxy in a galaxy group at z~ 2.5
Smail, Ian; Kneib, Jean-Paul; van der Werf, Paul P. +5 more
We present observations of a remarkable submillimetre-selected galaxy, SMM J16359+6612. This distant galaxy lies behind the core of a massive cluster of galaxies, A 2218, and is gravitationally lensed by the foreground cluster into three discrete images which were identified in deep submillimetre maps of the cluster core at both 450 and 850 µ…
Tracking of TRACE Ultraviolet Flare Footpoints
Fletcher, Lyndsay; Pollock, Jennifer A.; Potts, Hugh E.
Solar flares produce bright, compact sources of UV emission in the lower atmosphere, identified as flare footpoints. Observed at high time cadence with the Transition Region and Coronal Explorer, groups of UV footpoints define flare `ribbons' which move as the flare progresses. We have developed a procedure to track individual bright kernels withi…
Characteristics of Saturn's FUV aurora observed with the Space Telescope Imaging Spectrograph
Trauger, John T.; Gustin, Jacques; Clarke, John T. +3 more
We analyze a set of 15 FUV images obtained between October 1997 and January 2001 with the Hubble Space Telescope Imaging Spectrograph (STIS), providing a good view of Saturn's south auroral oval. It is found that the morphology and brightness distribution of the aurora are dynamical with variations occurring on time scales of hours or less. The da…
Real-time shock arrival predictions during the ``Halloween 2003 epoch''
Dryer, M.; Smith, Z.; Fry, C. D. +3 more
The ``Halloween'' epoch from 19 October to 20 November 2003 was marked by 19 major solar flares that were accompanied by metric type II radio bursts. Several of these flares were followed by major geomagnetic storms. The radio bursts were used in real time because they imply coronal and interplanetary transport. Most of these events were also asso…
Evolution in the Color-Magnitude Relation of Early-Type Galaxies in Clusters of Galaxies at z~=1
Dickinson, M.; Stanford, S. A.; Holden, B. P. +1 more
We present a study of the color evolution of elliptical and S0 galaxies in six clusters of galaxies inside the redshift range 0.78<z<1.27. For each cluster, we used imaging from the Hubble Space Telescope (HST) to determine morphological types of the galaxies. These types were determined both by an automated technique and from visual inspect…
WFI J2026-4536 and WFI J2033-4723: Two New Quadruple Gravitational Lenses
Rix, Hans-Walter; Dressler, Alan; Egami, Eiichi +3 more
We report the discovery of two new gravitationally lensed quasars, WFI J2026-4536 and WFI J2033-4723, at respective source redshifts of z=2.23 and z=1.66. Both systems are quadruply imaged and have similar PG 1115-like image configurations. WFI J2026-4536 has a maximum image separation of 1.4", a total brightness of g=16.5, and a relatively simple…
Predicted rotation signatures in MHD disc winds and comparison to DG Tau observations.
Dougados, C.; Ferreira, J.; Cabrit, S. +4 more
Motivated by the first detections of rotation signatures in the DG Tau jet (Bacciotti et al. \cite{bacciotti2002}), we examine possible biases affecting the relation between detected rotation signatures and true azimuthal velocity for self-similar MHD disc winds, taking into account projection, convolution as well as excitation gradients effects. …
Radiation-driven winds of hot luminous stars. XV. Constraints on the mass-luminosity relation of central stars of planetary nebulae
Pauldrach, A. W. A.; Hoffmann, T. L.; Méndez, R. H.
We present a new model atmosphere analysis of nine central stars of planetary nebulae. This study is based on a new generation of realistic stellar model atmospheres for hot stars; state-of-the-art, hydrodynamically consistent, spherically symmetric model atmospheres that have been shown to correctly reproduce the observed UV spectra of massive Po…