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Nitrogen Overabundance: Globular Cluster and Halo Formation
Burstein, David; Li, Yong
Halo globular clusters pose four succinct issues that must be solved in any scenario of their formation: single-age, single-metallicity stellar populations; a lower limit ([Fe/H]~-2.5) to their average metallicity; comprising only 1% of the stellar halo mass; and being among the oldest stars in our Galaxy. New spectra are presented of Galactic sta…
First NACO observations of the Brown Dwarf LHS 2397aB
Bouy, H.; Brandner, W.; Lagrange, A. M. +3 more
Observations of the standard late type M8 star LHS 2397aA were obtained at the ESO-VLT 8 m telescope ``Yepun'' using the NAOS/CONICA Adaptive Optics facility. The observations were taken during the NACO commissioning, and the infrared standard star LHS 2397aA was observed in the H, and Ks broad band filters. In both bands the brown dwarf companion…
Mid-infrared imaging of the dust shell around the post-asymptotic giant branch star HD 161796
Gledhill, T. M.; Yates, J. A.
We present mid-infrared (IR) images of HD 161796 (IRAS 17436+5003), taken with the OSCIR imager on the Gemini North Telescope, that resolve for the first time the thermal emission structure of the dust shell around this post-asymptotic giant branch (AGB) star. As well as a basic axisymmetric structure, the observations show deviations from axisymm…
Eruptive and Quasi-Eruptive Disappearing Solar Filaments and Their Relationship with Coronal Activities
Morimoto, Taro; Kurokawa, Hiroki
By measuring the 3-D velocity fields of 35 disappearing filaments (Disparition Brusques: DBs) on the solar disk, we studied the causal relationship between the motions of Hα DBs and the associated coronal phenomena. Using the derived 3-D velocity fields of the DBs, we developed a method to judge whether a DB is ejected into interplanetary space or…
NGC 2264 IRS 1: The Central Engine and Its Cavity
Stecklum, B.; Henning, Th.; Linz, H. +1 more
We present a high-resolution study of NGC 2264 IRS 1 in CS 2-->1 and in the 3 mm continuum using the IRAM Plateau de Bure interferometer. We complement these radio data with images taken at 2.2, 4.6, and 11.9 µm. The combined information allows a new interpretation of the closest environment of NGC 2264 IRS 1. No disk around the B-type st…
Propagation of energetic particles in the high-latitude high-speed solar wind
Dalla, S.; Forsyth, R. J.; Gosling, J. T. +4 more
We present observations of energetic particles in the energy range ~1 MeV to ~100 MeV made by the COSPIN instrument on board the Ulysses spacecraft during the recent second northern polar pass. For a short time during this pass the Ulysses spacecraft was at high heliographic latitude, above the current sheet, and immersed in high-speed solar-wind …
Radial velocities of early-type stars in the Perseus OB2 association
Steenbrugge, K. C.; de Bruijne, J. H. J.; de Zeeuw, P. T. +1 more
We present radial velocities for 29 B- and A-type stars in the field of the nearby association Perseus OB2. The velocities are derived from spectra obtained with AURELIE, via cross correlation with radial velocity standards matched as closely as possible in spectral type. The resulting accuracy is ~ 2-3 km s-1. We use these measurements…
Smaug: A New Technique for the Deprojection of Galaxy Clusters
Molendi, Silvano; Ghizzardi, Simona; De Grandi, Sabrina +1 more
This paper presents a new technique for reconstructing the spatial distributions of hydrogen, temperature, and metal abundance of a galaxy cluster. These quantities are worked out from the X-ray spectrum, modeled starting from few analytical functions describing their spatial distributions. These functions depend on some parameters, determined by …
Chandra and XMM-Newton observations of Tololo 0109-383
Brandt, W. N.; Perola, G. C.; Bianchi, S. +4 more
We present and discuss Chandra and XMM-Newton observations of the Seyfert 2 galaxy and Compton-thick absorbed source, Tololo 0109-383. The hard X-ray emission (i.e. above ~ 2 keV), is dominated by a spatially unresolved reflection component, as already discovered by previous ASCA and BeppoSAX observations. The soft X-ray emission is partly ( ~ 15%…
Impulses of activity and the Solar cycle
Benevolenskaya, Elena E.
Extreme-ultraviolet data from EIT/SOHO (1996-2002), soft X-ray data from Yohkoh (1991-2001), and magnetic field data from MDI/SOHO (1996-2002) and Kitt Peak Observatory, NSO/NOAO (1991-2002) are analyzed together in the form of synoptic maps for the investigation of solar cycle variations of the corona and their relation to the magnetic field. The…