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X-ray and extreme-ultraviolet emission from the coronae of Capella
Mathioudakis, M.; Keenan, F. P.; Phillips, K. J. H. +3 more
The primary objective of this work is the analysis and interpretation of coronal observations of Capella obtained in 1999 September with the High Energy Transmission Grating Spectrometer on the Chandra X-ray Observatory and the Extreme Ultraviolet Explorer (EUVE). He-like lines of O (Ovii) are used to derive a density of 1.7×1010cm…
Observations of the spatial and temporal structure of field-aligned beam and gyrating ring distributions at the quasi-perpendicular bow shock with Cluster CIS
Lundin, R.; Balsiger, H.; Dandouras, I. +23 more
During the early orbit phase, the Cluster spacecraft have repeatedly crossed the perpendicular Earth's bow shock and provided the first multi-spacecraft measurements. We have analyzed data from the Cluster Ion Spectrometry experiment (CIS), which observes the 3D-ion distribution function of the major species in the energy range of 5 eV to 40 keV w…
On the Nature of Intrinsic Absorption in Reddened Seyfert 1 Galaxies
Kraemer, S. B.; Crenshaw, D. M.
We discuss the origin of the ``dusty lukewarm absorber,'' which we previously identified in the reddened Seyfert 1 galaxies NGC 3227 and Akn 564. This absorber is characterized by saturated UV absorption lines (C IV, N V) near the systemic velocity of the host galaxy and is likely responsible for reddening both the continuum and emission lines (in…
Atomic Oxygen Abundance in Molecular Clouds: Absorption toward Sagittarius B2
Schilke, P.; Lis, D. C.; Phillips, T. G. +3 more
We have obtained high-resolution (~35 km s-1) spectra toward the molecular cloud Sgr B2 at 63 µm, the wavelength of the ground-state fine-structure line of atomic oxygen (O I), using the ISO-LWS instrument. Four separate velocity components are seen in the deconvolved spectrum, in absorption against the dust continuum emission of …
Evidence for micrometeoroid damage in the pn-CCD camera system aboard XMM-Newton
Aschenbach, B.; Trümper, J.; Kemmer, J. +9 more
The mirror systems of the X-ray observatory XMM-Newton were designed to image X-rays up to 15 keV by grazing incidence reflection onto a focal plane, equipped with Charge Coupled Devices (CCDs). In orbit # 156 we have observed a sudden increase of about 35 ``bright'' pixels spread over 15 cm2 in the pn-CCD camera system. The amount of l…
VLT spectroscopy of galaxies lensed by the AC 114 cluster:. Implications for the mass model and the study of low-luminosity galaxies at high-redshift
Smail, I.; Kneib, J. -P.; Pelló, R. +5 more
We present the first results of a spectroscopic survey of faint lensed galaxies in the core of the galaxy cluster AC 114 (z=0.312) obtained from observations with the FORS1 spectrograph mounted on the VLT-Antu (Unit Telescope 1). The galaxies were chosen according to both lensing and photometric redshift criteria in areas close to the high-z criti…
The Type IC SN 1990B in NGC 4568
Dickinson, Mark; Filippenko, Alexei V.; Shields, Joseph C. +25 more
We present a study of the Type Ic supernova (SN) 1990B that includes most of the observations obtained from around the world. The combined data set comprises 84 BV(RI)c photometric points spanning approximately 360 days after maximum light and 14 spectra from 5 up to ~150 days after maximum light. In contrast to other Type Ic SNe, SN 19…
Multiplicity of X-Ray-selected T Tauri Stars in Chamaeleon
Köhler, Rainer
We report on a multiplicity survey of a sample of X-ray-selected young stars in the Chamaeleon association. We used speckle interferometry and direct imaging to find companions in the separation range 0.13"-6". After correction for chance alignment with background stars, we find a multiplicity (number of binaries or multiples divided by number of …
Electromagnetic heavy ion cyclotron instability: Anisotropy constraint in the solar corona
Gary, S. Peter; Ofman, Leon; Winske, Dan +1 more
The electromagnetic proton cyclotron anisotropy instability is driven by T⊥p/T∥p>1 where p represents protons and the directional subscripts denote directions relative to the background magnetic field. Fluctuating field growth leads to wave-particle scattering, which in turn imposes an upper bound on the anisotropy of the …
IUE Absorption-Line Observations of the Moderately and Highly Ionized Interstellar Medium toward 164 Early-Type Stars
Sembach, Kenneth R.; Savage, Blair D.; Meade, Marilyn R.
We present measurements of Galactic interstellar Al III, Si IV, and C IV absorption recorded in high-resolution archival ultraviolet spectra of 164 hot early-type stars observed by the International Ultraviolet Explorer (IUE) satellite. The objects studied were drawn from the list of hot stars scheduled to be observed with the Far Ultraviolet Spec…