Search Publications
The host to gamma-ray burst 970508: a distant dwarf galaxy?
Galama, T. J.; Bloom, J. S.; Kouveliotou, C. +6 more
If the optical transient to gamma-ray burst (GRB) 970508 is indeed associated with the 8 May burst and is connected with the z = 0.835 absorption system reported by Metzger et al. (1997) [Natur, 387, 879], then either the GRB originated from an intrinsically very faint galaxy (L ≲ 0.01L∗) or it occurred at a large distance from a host g…
Low-mass stars and star clusters in the dark Galactic halo
Kerins, E. J.
In a previous study it was proposed that the Galactic dark matter being detected by gravitational microlensing experiments such as MACHO may reside in a population of dim halo globular clusters comprising mostly or entirely low-mass stars just above the hydrogen-burning limit. It was shown that, for the case of a standard isothermal halo, the scen…
HST confirmation of the lensed quasar J03.13.
Surdej, J.; Claeskens, J. -F.; Remy, M. +4 more
In order to definitely prove the claim by Claeskens et al. (1996A&A...305L...9C) that J03.13 is a doubly imaged quasar, WFPC2 direct imaging and FOS spectroscopy of this compact system have been obtained with HST. These textbook case observations clearly show that J03.13 consists of two point-like images separated by 0.849"+/-0.001" with a mag…
The Spectrum of the Planetary Nebula NGC 6884
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H.
The bright, compact, moderately high-excitation planetary nebula, NGC 6884 (Perek-Kohoutek 82 +07°1) has a rich spectrum promising good diagnostics and offering a good target for the Hamilton Echelle Spectrograph at Lick Observatory. We combine International Ultraviolet Explorer (IUE), near-UV, visual, and IR data to obtain N(ion)/N(H+)…
Mass and radius of the white dwarf in the binary V471 Tau from ORFEUS and HIPPARCOS observations.
Rauch, T.; Werner, K.
We present a model atmosphere analysis of the white dwarf component in the K2V/DA eclipsing binary system V471 Tau, based upon FUV spectra obtained by the ORFEUS satellite. This system is regarded as the prototype of a post-common envelope WD+MS binary and, hence, is of considerable importance for our understanding of close binary evolution. From …
Spectroscopic study of the planetary nebulae with Wolf-Rayet nuclei in the Magellanic Clouds.
Pena, M.; Torres-Peimbert, S.; Ruiz, M. T.
UV and optical spectrophotometric data of planetary nebulae with WR nuclei in the Magellanic Clouds are presented. Analysis of the nebular characteristics shows that the ionized gas, in all the objects, is extremely C-rich, probably due to contamination with freshly-made C from stellar nucleosynthesis. Very high electron densities are found (N_e_&…
Blue stars in the center of the S0 galaxy NGC 5102.
Crane, P.; Disney, M. J.; Jedrzejewski, R. +2 more
The S0 galaxy NGC 5102 has been observed with the Faint Object Camera on-board the Hubble Space Telescope. Individual blue stars have been resolved in the central region and measured photometrically through the F175W and F342w filters. The limits of detection and completeness are not uniform over the field observed because the unresolved galaxy li…
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…
HST polarization observations of the jet of M87.
Macchetto, F. D.; Capetti, A.; Sparks, W. B. +1 more
We present the results of pre-refurbishment HST polarization observations of the jet of M 87 taken with the Faint Object Camera in the ultraviolet and with the WF/PC-I in the visual. From these observations we produce polarization maps of unprecedentedly high resolution. The structure of the projected magnetic field is extremely complex and change…
UV to X-ray spectra of radio-quiet quasars. Comparison with accretion disk models.
Brunner, H.; Staubert, R.; Mueller, C. +3 more
We present UV to soft X-ray spectra of 31 radio-quiet quasars, comprising data from the IUE ULDA database and the ROSAT pointed observation phase. 90 % of the sample members show a soft X-ray excess above an underlying hard X-ray power law spectrum. Particularly for the steep X-ray spectrum (α_energy_>1.5), low redshift subsample (17 objects) t…