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H-alpha interferometric, optical and near IR photometric studies of star forming regions. I. The Cepheus B/Sh2-155/Cepheus OB3 association complex.
Wagner, S.; Moreno-Corral, M. A.; C., Chavarria-K. +1 more
Here we report the results of a near IR photo- metric study of about 40 stars of the Cepheus OB3 association (subpopulations a and b), of an attempt to detect near IR counterparts of the discrete radio continuum sources reported by Felli et al. (1978), and of the nature of the IR source AFGL 3000. We also give the results of a Hα interferometric, …
Simultaneous ROSAT, GINGA, VLA, IUE, and Optical Observations of the Bright Quasar H1821+643
Filippenko, Alexei V.; Halpern, Jules P.; Fink, Henner H. +3 more
We report on the first simultaneous optical, UV, and X-ray spectroscopy of the low-redshift (z = 0.297), high-luminosity QSO H 1821 + 643. This multiwavelength campaign was complemented by optical imaging and radio mapping with the VLA. Although there was no significant variability during the 40 day monitoring period in either the UV or X-ray band…
Multifrequency Observations of the Optically Active Radio-quiet Quasar GQ Comae. II. Ultraviolet, Optical, and Infrared Continuum Variability
Sitko, Michael L.; Szczerba, R.; Siemiginowska, Aneta +1 more
This paper summarizes the data and preliminary results of a 3 yr long project to monitor the continuum variability of GQ Comae (PG 1202+281) from 0.12 microns to 3.5 microns. Substantial variability in the optical/ultraviolet flux was observed. The variability is examined using a geometrically thin accretion disk model. The model is able to reprod…
Pickup water group ions at comet Grigg-Skjellerup
Coates, A. J.; Winningham, J. D.; Borg, H. +9 more
The density and velocity distribution of cometary water group ions was measured by the Giotto spacecraft in the regions upstream and downstream of the ‘bow shock’ at comet Grigg-Skjellerup. The results show that the distributions of ions are ring-like until quite close to the shock, the timescales for pitch angle and energy diffusion appear simila…
Detection of Accreting Gas toward HD 45677: A Newly Recognized, Herbig Be Proto--Planetary System
Grady, C. A.; Perez, M. R.; The, P. S. +4 more
We report the detection of high-velocity, accreting gas toward the BE(e) star with IR excess and bipolar nebula, HD 45677. High-velocity (+200 to +400 km/s), variable column density gas is visible in all IUE spectra from 1979 to 1992 in transitions of Si II, C II, Al III, Fe III, Si IV, and C IV. Low-velocity absorption profiles from low oscillato…
Imaging of the Gravitational Lens System PG 1115+080 With the Hubble Space Telescope
Holtzman, J. A.; Ewald, S. P.; Schneider, D. P. +14 more
This paper is the first of a series presenting observations of gravitational lenses and lens candidates, taken with the Wide Field/Planetary Camera (WFPC) of the Hubble Space Telescope (HST). We have resolved the gravitational lens system PG 1115+080 into four point sources and a red, extended object that is presumably the lens galaxy; we present …
The Hubble Space Telescope Snapshot Survey. III. Further Observations in Search of Gravitationally Lensed Quasars
Maoz, D.; Lahav, O.; Schneider, D. P. +4 more
We present new HST Snapshot Survey observations of 163 high-luminosity z > 1 quasars, bringing the total number observed to date in the survey to 347 quasars. Each exposure was searched for evidence of gravitational lensing. Among the newly observed quasars, six have additional point sources at separations of 2"-6", but in all six cases ground-…
The Circumstellar Gas Surrounding 51 Ophiuchi: A Candidate Proto--Planetary System Similar to beta Pictoris
Grady, C. A.; Silvis, J. M. S.
Combined archival and recent International Ultraviolet Explorer (IUE) observations of the star, 51 Oph, reveal the presence of variable, accreting gas with velocities as large as + 100 km/s relative to the system. The electron number density of the circumstellar gas is comparable to that observed around the candidate proto-planetary system, Beta P…
RE 1016-053: A Pre-Cataclysmic Binary, and the First Extreme Ultraviolet and X-Ray Detections of DAO White Dwarf
Barstow, M. A.; Bergeron, P.; Holberg, J. B. +4 more
Photometric observations and analysis of the optical, UV, EUV, and X-ray spectra are presented for the EUV/X-ray source RE 1016-53. Multiwavelength observations of RE 1016-53 point out that it is a precataclysmic binary. Optical spectra exhibit the steep blue continuum and Balmer absorption typical of a hot white dwarf, but there are bright, narro…
The Structure of the Core of 47 Tucanae from Hubble Space Telescope Observations
Ferraro, Francesco R.; Paresce, Francesco; de Marchi, Guido
A set of moderately deep, high-resolution images of the core of the Galactic globular cluster NGC 104 (47 Tucanae) taken by the Faint Object Camera F/48 relay on the Hubble Space Telescope through the filters F140W, F220W, and F342W are presented and analyzed. The core is completely resolved in these bands for the first time, with approximately 35…