Search Publications
Observing Stellar Coronae with the Goddard High Resolution Spectrograph. II. The RS CVn Binary System HR 1099
Carpenter, K. G.; Robinson, R. D.; Airapetian, V. S. +1 more
We report time series observations of the RS CVn star HR 1099 taken with the Goddard High Resolution Spectrograph onboard the Hubble Space Telescope. The data cover a wavelength range from 1342 to 1375 Å and show a measurable continuum, as well as emission lines of O I, C I, CII, Fe II, O V, and Fe XXI. The chromospheric and transition region feat…
The Starburst Nuclear Region in M82 Compared in Several Wave Bands
Golla, Goetz; Allen, Michael L.; Kronberg, Philipp P.
We utilize new, sensitive radio continuum images of M82 at 1.5, 15 and 22 GHz for a comparison with images at other wave bands that have recently appeared in the literature. Overlays of the radio data with images in the optical V band (Hubble Space Telescope observations), mid- infrared, the [Ne II] line, and the CO (1 - 0) and the HCN line are pr…
WFPC2 Imaging of the Starburst Galaxy NGC 5253
Gorjian, Varoujan
A high-resolution F606W band image has been obtained with the WFPC2 instrument on the Hubble Space Telescope of the unusual starburst galaxy NGC 5253. This is a dwarf elliptical galaxy with a very young starburst in progress. The HST image is compared to ground-based data in the Hα and 2 cm wavebands to draw correlations between the high- resoluti…
The spectrum of the planetary nebula IC 351
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H.
International Ultraviolet Explorer (IUE) and optical region spectroscopic observations are presented for the moderately high-excitation planetary nebula IC 351. Most of the atoms are distributed over a narrow range of ionization. Thus [NII] and [SII] are weak; [NeIV] is prominent, but [NeV] is missing. It appears that the metal/hydrogen ratio is s…
Strong Clustering in the Low-Redshift Ly alpha Forest
Ulmer, Andrew
The two-point correlation function, ξ, of Lyα forest is found to be large, ξ = 1.8^+1.6^_-1.2_, greater than 90% confidence level, on the scale of 250-500 km s^-1^ for a sample of absorbers (0 < z < 1.3) assembled from Hubble Space Telescope Key Project Observations. This correlation function is stronger than at high redshift (z > 1.7) wh…
Determination of interstellar helium parameters from the ULYSSES-NEUTRAL GAS experiment: Method of data analysis.
Rosenbauer, H.; Witte, M.; Banaszkiewicz, M.
The GAS instrument on board the ULYSSES spacecraft has, for the first time, measured directly the interstellar flux of helium atoms in the inner solar system. From the locally measured angular distribution of the flux, the task is to derive the five parameters of the Maxwellian distribution function: density, bulk velocity vector, and temperature …
The Interstellar Gas Flow Through the Heliospheric Interface Region
Fahr, Hans J.
The relative motion of the solar system with respect to the ambient interstellar medium forms a plasma interface region where the eventually subsonic, interstellar and solar wind plasma flows adapt to each other. In this region ahead of the solar system magnetohydrodynamically perturbed plasma flows are formed which, however, can be penetrated by …
The Spectrum of the Planetary Nebula NGC 6790
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H.
International Ultraviolet Explorer (IUE) and optical region spectroscopic observations are presented for the medium excitation planetary nebula (PN), NGC 6790, which displays a rich spectrum permitting application of several diagnostic ratios and the calculation of a number of ionic concentrations, N(ion)/N(H+). NGC 6790 seems to be a relatively y…
Globular Cluster Luminosity Functions and the Hubble Constant From WFPC2 Imaging: The Giant Elliptical NGC 4365
Forbes, Duncan A.
The turnover, or peak, magnitude in a galaxy's globular cluster luminosity function (GCLF) may provide a standard candle for an independent distance estimator. Here we examine the GCLF of the giant elliptical NGC 4365 using photometry of ~350 globular clusters from the Hubble Space Telescope's Wide Field and Planetary Camera 2 (WFPC2). The WFPC2 d…
The infrared and radio continuum of early-type stars.
Blomme, R.; Runacres, M. C.
The infrared and radio continuum fluxes of 18 well-observed early-type stars are studied by comparing observations with theoretical models. The observations are taken from the literature. All available observations are included. The theoretical NLTE models for photosphere and stellar wind include free-free and free-bound emission as well as electr…