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Coronal and Transition Region Structure in the RS Canum Venaticorum Binaries V711 Tauri, AR Lacertae, and II Pegasi. I. Data Analysis and Emission Measure Distributions
Jordan, C.; Griffiths, N. W.
We present a study of the transition regions and coronae of the RS CVn binaries V711 Tau, AR Lac, and II Peg. Archival data from the Extreme Ultraviolet Explorer (EUVE), International Ultraviolet Explorer (IUE), Goddard High-Resolution Spectrograph (GHRS), and a variety of X-ray telescopes have been analyzed and modeled. Emission measure distribut…
NICMOS 2 Micron Continuum and H2 Images of OMC-1
Schneider, Glenn; Chrysostomou, Antonio; Young, Erick T. +8 more
The core of OMC-1 has been imaged with the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) on board the Hubble Space Telescope at 0.2" resolution in 1% filters at 2.12 and 2.15 µm, revealing intricate structures in both continuum and shocked molecular hydrogen line emission. Numerous H2-emitting clumps surrounding the B…
Toward a Realistic Diffusion Tensor for Galactic Cosmic Rays
Burger, R. A.; Hattingh, M.
We present analytical expressions for the mean free path parallel to the background magnetic field, calculated from quasi-linear theory for a composite slab/two-dimensional geometry model of turbulence. Diffusion perpendicular to the field is assumed to be anisotropic and proportional to parallel diffusion. For the variation in the magnetic field …
The beta Pictoris circumstellar disk. XXIV. Clues to the origin of the stable gas
Deleuil, M.; Spyromilio, J.; Feldman, P. D. +11 more
GHRS high resolution spectra of {beta \:Pictoris} were obtained to study the stable gas around this star. Several elements are detected and their abundances measured. Upper limits to the abundances of others are also measured. The data permit improved chemical analysis of the stable gas around {beta \:Pictoris}, and yield new and more accurate est…
Proper Motions in the Ejecta of η Carinae with a 50 Year Baseline
Smith, Nathan; Gehrz, Robert D.
Observations of η Carinae from three separate epochs spanning a total of 50 years are used to measure the proper motions of several easily identifiable features in the Homunculus Nebula. Our principal conclusion is that the equatorial features were ejected significantly after the ``Great Eruption,'' very likely in the outburst that occurred around…
Mode switching in the nearby Mira-like variable R Doradus
Bedding, T. R.; Jones, A.; Zijlstra, Albert A. +1 more
We discuss visual observations spanning nearly 70 years of the nearby semiregular variable R Doradus. Using wavelet analysis, we show that the star switches back and forth between two pulsation modes having periods of 332d and about 175d, the latter with much smaller amplitude. Comparison with model calculations suggests that the two modes are the…
HST imaging of the globular clusters in the Fornax cluster: NGC1399 and NGC1404
Forbes, Duncan A.; Brodie, Jean P.; Grillmair, Carl J. +2 more
The Fornax cluster galaxies NGC1399 and NGC1404 are ideal for studying the effects of a cluster environment on globular cluster systems. Here we present new optical imaging of these two galaxies from both the Hubble Space Telescope's Wide Field and Planetary Camera 2 and the Cerro Tololo Inter-American Observatory 1.5-m telescope. The combination …
Two Jets from the Protostellar System L1551 IRS 5
Liseau, René; Fridlund, C. V. Malcolm
Hubble Space Telescope and ground-based observations of the jet emanating from the young stellar object L1551 IRS 5 clearly show a structure with two components, one of which terminates in a working surface only 1500 AU from the originating sources. This particular jet is found to be less dense than the ambient medium. Its Mach disk is found to be…
The Virgo Cluster Distance from 21 Centimeter Line Widths
Sandage, Allan; Tammann, G. A.; Federspiel, Martin
The distance of the Virgo cluster is derived in the B band from the 21 cm line width-absolute magnitude relation. This relation is calibrated using 18 spirals with Cepheid distances, mainly from the Hubble Space Telescope. The calibration is applied to a complete sample of nonpeculiar spirals with i > 45° lying within the optical (n = 49) or X-…
Color-Luminosity Relations for the Resolved Hot Stellar Populations in the Centers of M31 and M32
Ferguson, Henry C.; Brown, Thomas M.; Stanford, S. A. +1 more
We present Faint Object Camera (FOC) ultraviolet images of the central 14" × 14" of Messier 31 and Messier 32. The hot stellar populations detected in the composite UV spectra of these nearby galaxies are partially resolved into individual stars, and their individual colors and apparent magnitudes are measured. We detect 433 stars in M31 and 138 s…