Search Publications
Search for Interstellar Water in the Translucent Molecular Cloud toward HD 154368
Stauffer, John; Neufeld, David; Melnick, Gary J. +2 more
We report an upper limit of 9 × 1012 cm-2 on the column density of water in the translucent cloud along the line of sight toward HD 154368. This result is based on a search for the C-X band of water near 1240 Å carried out using the Goddard High-Resolution Spectrograph (GHRS) of the Hubble Space Telescope. Our observational l…
WFPC2 Observations of NGC 454: An Interacting Pair of Galaxies
Panagia, N.; Stiavelli, M.; Romaniello, M. +3 more
We present Wide Field Planetary Camera 2 images in the F450W, F606W, and F814W filters of the interacting pair of galaxies NGC 454. Our data indicate that the system is in the early stages of interaction. A population of young star clusters has formed around the late component, and substantial amounts of gas have sunk into the center of the earlie…
A Fit to the Simultaneous Broadband Spectrum of Cygnus X-1 Using the Transition Disk Model
Misra, R.; Melia, Fulvio; Chitnis, V. R.
We have used the transition disk model to fit the simultaneous broadband (2-500 keV) spectrum of Cygnus X-1 from OSSE and Ginga observations. In this model, the spectrum is produced by saturated Comptonization within the inner region of the accretion disk, where the temperature varies rapidly with radius. In an earlier attempt, we demonstrated the…
Limits on the Boron Isotopic Ratio in HD 76932
Rebull, Luisa; Duncan, Douglas; Johansson, Sveneric +2 more
Data in the λ2090 B region of HD 76932 have been obtained at a high signal-to-noise ratio using the Hubble Space Telescope Goddard High-Resolution Spectrograph echelle at a resolution of 90,000. This wavelength region has been previously identified as a likely candidate for observing the 11B/10B isotopic splitting. The observ…
Far-Ultraviolet and Visible Imaging of the Nucleus of M32
Casertano, Stefano; Cole, Andrew A.; Ballester, Gilda E. +15 more
We have imaged the nucleus of M32 at 1600 Å (FUV) and 5500 Å (V) using the Wide-Field/Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope. We detected the nucleus at 1600 Å using the redleak-free Woods filter on WFPC2. The far-ultraviolet (FUV) light profile can be fitted with a Gaussian of FWHM 0.46" (4.6 pixels) but cannot be resolved i…
ORFEUS Observations of Luminous Cool Stars
Dupree, A. K.; Brickhouse, N. S.
The ORFEUS telescope obtained far-ultraviolet spectra (λλ912-1218) of three luminous cool stars: β Draconis (HD 159181) and two hybrid stars, α Aquarii (HD 209750) and α Trianguli Australis (HD 150798). Most striking is the detection of blueshifted O VI λ1032, and C III λ977 emission relative to Si III λ1206, indicating outward motion, and the mar…
Progressive Star Bursts and High Velocities in the Infrared-luminous, Colliding Galaxy ARP 118
Gao, Yu; Lamb, Susan A.; Hearn, Nathan C.
In this Letter, we demonstrate for the first time the connection between the spatial and temporal progression of star formation and the changing locations of the very dense regions in the gas of a massive disk galaxy (NGC 1144) in the aftermath of its collision with a massive elliptical galaxy (NGC 1143). These two galaxies form the combined objec…
The Mass of the Cepheid Binary V636 Scorpii
Albrow, Michael D.; Cottrell, P. L.; Evans, N. R. +4 more
The mass-luminosity relation for Cepheids depends on the degree of mixing in their main-sequence progenitors. Masses of Cepheids can be inferred by using different aspects of pulsation theory. These methods have in the past led to diverging results, showing that something was wrong in either evolution theory or pulsation theory or both. For some b…
ORFEUS-SPAS II Observations of the Ultraviolet-bright Star Barnard 29 in M13
Hurwitz, Mark; Dixon, W. Van Dyke
The UV-bright star Barnard 29 in the globular cluster M13 was observed with the Berkeley spectrometer on the ORFEUS-SPAS II mission in 1996 November-December. The resulting spectrum extends from the interstellar cutoff at 912 A to ~1200 A at a resolution of ~0.33 A. It shows numerous absorption features, both photospheric and interstellar, but no …
Kinematic Substructure of Halo Stars from HIPPARCOS Observations
Chen, B.
With highly accurate parallaxes and proper motions observed by HIPPARCOS, we discuss the distributions of velocities and metallicities for a sample of stars selected from the Lowell Proper Motion Catalog. Cluster analysis is used to search for natural groups in the sample and display them graphically. Data presented in this Letter support the pict…