Search Publications
Star Counts from the HST Snapshot Survey. II. Wide Binaries
Maoz, Dan; Gould, Andrew; Yanny, Brian +1 more
We report on a study of the first sample of wide binaries whose members are primarily in the old component of the Galactic disk. The binaries were discovered in 446 fields imaged with the Hubble Space Telescope (HST) Planetary Camera to an average magnitude limit of V = 2.13, as part of the Snapshot Survey for gravitational lenses. Most of the fie…
Identification of Emission-Line Stars in 30 Doradus Using HST Observations
Parker, Joel Wm.; Heap, Sara R.; Malumuth, Eliot M.
Using broadband (F439W) and narrowband (F469N) Hubble Space Telescope archive images of the R136 central cluster of 30 Doradus, we have identified candidate Wolf-Rayet stars from the strength of their He II λ4686 emission lines. The number ratio of Wolf-Rayet to O stars found in our data is 0.11±0.03. Our results are more consistent with an instan…
Ultraviolet Temporal Variability of the Peculiar Star R Aquarii
Kafatos, M.; Meier, S. R.
This paper is a comprehensive study of all far-UV spectra obtained with the International Ultraviolet Explorer (IUE) satellite of the symbiotic star R Aquarii (R Aqr) covering a 13 yr period between 1979 and 1992. We have analyzed the ultraviolet emission for the compact H II region and the NE and SW extended "jetlike" filamentary structures. The …
Velocity Profile of the Ionized Disk and the Mass of the Black Hole in M87
Chakrabarti, Sandip K.
We present a theoretical model for the ionized disk in M87 which includes spiral shock waves. The line emission profiles computed from this model at various positions on the disk are found to be in agreement with the recent Hubble Space Telescope results. Based on this model, we find that the ionized disk comprises two-armed giant spiral shock wav…
A Search for r-Process Elements in the VELA Supernova Remnant
Jenkins, Edward B.; Wallerstein, George; Vanture, Andrew D. +1 more
After a description of recent developments in the physics of rapid neutron capture in Type II supernovae and a discussion of the detectability of supernovae ejecta, we present the data from a search for Ge, Kr, Yb, Os, and Hg in five stars behind or within the Vela remnant. Only Ge ii was detected, but its column density and the upper limits of th…
Goddard High-Resolution Spectrograph Observations of the Interacting Binary System W Serpentis
Rosenblatt, E. I.; Shore, S. N.; Weiland, J. L. +2 more
Spectroscopic observations of the interacting binary system W Serpentis have been made at two orbital phases using the Goddard High-Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST). Differences in Si IV t393, 1403λλ emission-line strengths and profile shapes observed between the two phases suggest that a hot spot exists where…
Interstellar Lines in HD 72127A and B: A Binary Star behind the VELA Supernova Remnant
Jenkins, Edward B.; Wallerstein, George; Vanture, Andrew
Spectra with a resolution of 20,000 obtained with the Goddard High Resolution Spectrograph on board Hubble Space Telescope show substantial differences in the interstellar absorption features for two stars, HD 72127A and B, despite their small separation of 4'S. Some of the material that produces these features is associated with shocked clouds in…
Properties of the +70 Kilometers per Second Cloud toward HD 203664
Sembach, Kenneth R.
I present high-resolution International Ultraviolet Explorer (IUE) spectra of the ultraviolet absorption in an intermediate-velocity interstellar cloud (nuLSR approximately equal to +70 km/s) toward HD 203664. The combined, multiple IUE images result in spectra with S/N = 15-40 and resolutions of approximately 20-25 km/s. The intermedia…
Medium-Resolution Far-Ultraviolet Spectroscopy of PKS 2155-304
Grewing, M.; Hurwitz, M.; Bowyer, S. +5 more
Using the Berkeley spectrometer of the Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) we observed the 87-117 nm UV spectrum of the BL Lac object PKS 2155 - 304 with about 0.5 A resolution. In addition to the expected interstellar lines we detected higher quantum number counterparts of the intergalactic Lyα lines discovered …
Far-Ultraviolet (912--1900 Angstrom ) Energy Distribution in Early-Type Main-Sequence Stars
Chavez, M.; Holberg, J. B.; Stalio, R.
We present the comparison between observed far-ultraviolet (FUV) fluxes of early-type stars and those predicted by the most recent classical LTE, line-blanketed models of Kurucz. High-quality lUE spectra from the Uniform Low Dispersion Archive (ULDA) of more than 100 stars are selected. The averages of the observed fluxes, normalized to the visual…