Search Publications
Hubble Space Telescope Imaging of the Host Galaxies of Three X-Ray-selected BL Lacertae Objects
Yanny, Brian; Jannuzi, Buell T.; Impey, Chris
Hubble Space Telescope (HST) WFPC-2 I-band (F814W) images of three X-ray-selected BL Lacertae objects (MS 1221.8+2452, MS 1407.9+5954, and MS 2143.4+0704) reveal that each of these BL Lac objects is well centered in an extended nebulosity that is consistent in brightness and morphology with light from an elliptical galaxy at their previously repor…
An Interstellar Conduction Front within a Wolf-Rayet Ring Nebula Observed with the Goddard High Resolution Spectrograph
Chu, You-Hua; McCray, Richard; Boroson, Bram +4 more
With the High Resolution Spectrograph aboard the Hubble Space Telescope we obtained high signal-to-noise ratio (S/N >~ 200-600 per 17 km s-1 resolution element) spectra of narrow absorption lines toward the Wolf-Rayet star HD 50896. The ring nebula S308 that surrounds this star is thought to be caused by a pressure-driven bubble boun…
Motion of the Ultraviolet R Aquarii Jet
Feibelman, W. A.; Hollis, J. M.; Dorband, J. E. +1 more
We present evidence for subarcsecond changes in the ultraviolet (~2550 Å) morphology of the inner 5 arcseconds of the R Aqr jet over a 2 yr period. These data were taken with the Hubble Space Telescope (HST) Faint Object Camera (FOC) when the primary mirror flow was still affecting observations. Images of the R Aqr stellar jet were successfully re…
The Nature and Origin of za ~ ze Absorption Lines in the Redshift 0.20 Quasar, PKS 2135-147
Hamann, Fred; Cohen, Ross D.; Burbidge, E. M. +3 more
We use new UV and optical spectra and an archival Hubble Space Telescope Wide Field Planetary Camera 2 (HST-WFPC2) image to study the za ~ ze absorber in the ze ~ 0.20 QSO PKS 2135-147. The UV spectra, obtained with the Faint Object Spectrograph on HST, show strong za ~ ze absorption lines of …
Star Formation and Metal Production as a Function of Redshift: The Role of the Multiphase ISM
Carollo, C. Marcella; Spaans, Marco
We present models of the cosmological star formation and metal production history of (proto)galaxies with varying axis ratios. More massive and/or roughly spherical systems reach the threshold metallicity for the transition to a multiphase interstellar medium earlier than less massive and/or more flattened systems. Therefore, more flattened and/or…
Dynamic Processes in Be Star Atmospheres. V. Helium Line Emissions from the Outer Atmosphere of λ Eridani
Smith, Myron A.; Cohen, D. H.; Basri, G. +5 more
The He I lines of the mild B2e star λ Eri often exhibit rapid, small-amplitude emissions that can occur at random places in their photospheric lines, even when the star is in a ``nonemission state.'' New simultaneous observations of the triplet λ5876 and singlet λ6678 lines show that the emission ratio for these lines is near unity, contrary to th…
A White Dwarf Companion to the B5 V Star HR 2875 (y Puppis)
Vennes, Stéphane; Christian, Damian J.; Berghöfer, Thomas W.
An extreme-ultraviolet source in the EUVE and ROSAT Wide Field Camera catalogs, also identified with a very soft ROSAT PSPC X-ray source, is coincident with the B5 V star HR 2875 (y Pup). We present an analysis of PSPC and EUVE spectra revealing the presence of a hot white dwarf companion to HR 2875, which then constitute the first confirmed B sta…
Hubble Space Telescope Imaging of the BL Lacertae Object OJ 287
Yanny, Brian; Jannuzi, Buell T.; Impey, Chris
Hubble Space Telescope WFPC-2 I-band (F814W) images of the BL Lacertae object OJ 287 and the surrounding field are presented. We find evidence of associated extended nebulosity near OJ 287, as well as a small nebulosity to the west, which may be spatially coincident with the position of previously observed radio emission. The brightness of a host …
A Self-consistent Photoionization-Dust Continuum-Molecular Line Transfer Model of NGC 7027
Volk, Kevin; Kwok, Sun
A model to simulate the entire spectrum (1000 Å to 1 cm) of the high-excitation young planetary nebula NGC 7027 is presented. The ionized, dust, and molecular components of the object are modeled using geometric parameters obtained from visible, radio, infrared, and CO data. The physical processes considered include recombination lines of H and He…
New Perspectives on AX Monocerotis
Wilson, R. E.; Güdel, Manuel; Guinan, Edward F. +6 more
AX Moncerotis is a 232d, noneclipsing, interacting binary star that consists of a K giant, a Be-like giant, and large amounts of circumstellar material. The K star is almost certainly a synchronous rotator and is probably in contact with its critical lobe. The Be star was believed to be a rapid rotator based on extremely wide absorption…