Search Publications
The Coolest DA White Dwarfs Detected at Soft X-Ray Wavelengths
Barstow, M. A.; Wesemael, F.; Holberg, J. B. +2 more
New soft X-ray/EUV photometric observations of the DA white dwarfs KPD 0631 + 1043 = WD 0631 + 107 and PG 1113 + 413 = WD 1113 + 413 are analyzed. Previously reported soft X-ray detections of three other DAs and the failure to detect a fourth DA in deep Exosat observations are investigated. New ground-based spectra are presented for all of the obj…
Ultraviolet and Optical Spectral Morphology of Melnick 42 and Radcliffe 136a in 30 Doradus
Walborn, Nolan R.; Ebbets, Dennis C.; Parker, Joel Wm. +2 more
HST/GHRS ultraviolet spectrograms of the individual O3 If */WN6-A object Mk 42 in 30 Dor and the adjacent, central multiple system R136a are compared with each other and with an appropriate sequence of O3 If* and WN6-A standards from the IUE archive. The analogous spectral montages covering the blue-violet region, based on new, homogeneous, digita…
Far-Ultraviolet Observations of the Crab Nebula Using the Hopkins Ultraviolet Telescope
Blair, William P.; Kriss, Gerard A.; Davidsen, Arthur F. +5 more
Observations of the FUV spectrum of the central portion of the Crab Nebula SNR using the Hopkins Ultraviolet Telescope (HUT) aboard the Astro-1 space shuttle mission in December 1990 are reported. The C IV 1549-A emission line shows two resolved components representing the front and back sides of the shell expanding at roughly +/- 1100 km/s. The H…
Hubble Space Telescope Imaging of the Large-Redshift Gravitational Lens Candidate 1208+1011
Maoz, Dan; Schneider, Donald P.; Yanny, Brian +2 more
Four-color photometry obtained with the Hubble Space Telescope is consistent with the hypothesis that the light from the quasar 1208+1011 (z = 3.8) is gravitationally lensed. Guided exposures taken with the HST Planetary Camera resolve the quasar image into two point-source components separated by 0.476" +/- 0.004". The intensity ratio of the comp…
A Gravitational Lens Candidate Discovered with the Hubble Space Telescope
Filippenko, Alexei V.; Maoz, Dan; Schneider, Donald P. +6 more
We report evidence for gravitational lensing of the high-redshift (z = 3.8) quasar 1208+101, observed as part of the Snapshot Survey with the Hubble Space Telescope Planetary Camera. An HST V image taken on gyroscopes resolves the quasar into three point-source components, with the two fainter images having separations of 0.1" and 0.5" from the ce…
Twin Peaks: IC 4329A and Arakelian 120
Marziani, P.; Sulentic, J. W.; Calvani, M.
New spectrophotometric observations of the Seyfert 1 galaxies IC 4329A and Arakelian 120 are presented. The low-ionization broad emission lines (as evidenced by Hβ) are strikingly similar. The so-called zero peak in the Balmer lines of these objects appears to be both broader than and blueshifted relative to the [O III] λλ4959, 5007 lines. It is a…
The Near-Ultraviolet Spectrum of Markarian 205
Jenkins, Edward B.; Schneider, Donald P.; Jannuzi, Buell T. +2 more
We report measurements of the absorption and of the emission lines between 1600 and 3200 A in the spectrum of the nearby AGN Markarian 205 (z = 0.071), which lies at a projected distance of 3 kpc (H_0_= 100 km s^-1^) from the nucleus of the nearby barred spiral galaxy NGC 4319 (z = 0.0047). The results were obtained using high-resolution (R = 1300…
Ultraviolet Imaging Telescope Observations of the Cygnus Loop
Jenkins, Edward B.; Gull, Theodore R.; Cheng, Kwang-Ping +8 more
Attention is given to UV images of a 40-arcmin field in the northeast part of the Cygnus Loop made by the Ultraviolet Imaging Telescope (UIT) during the Astro-1 mission in December 1990. The longest FUV (B5) exposure is compared with ground-based and X-ray observations and with models. It is inferred from SNR shock models that C IV 1550 A dominate…
Comparing Restored HST and VLA Imagery of R Aquarii
Hollis, J. M.; Yusef-Zadeh, F.; Dorband, J. E.
The maximum entropy method is applied to Hubble Space Telescope data taken of the R Aquarii binary system and its jet with the Faint Object Camera in order to restore an image in forbidden O III at 5007 A plagued by spherical aberration and detector saturation. These results are compared with 2-cm radio continuum imagery taken with the Very Large …
The Diffuse Interstellar Cloud toward HD 179406 (20 Aquilae)
Snow, Theodore P.; Black, John H.; Hanson, Margaret M.
An analysis of the diffuse interstellar cloud complex in front of HD 179406 (20 Aql) is presented. Along this sight line, multispectral absortion- and emission-line studies have uncovered at least three distinct velocity components due to individual clouds. A dominant velocity component is seen in both the absorption and emission-line data sets at…