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Spectrophotometric Data of the Central Star of the Large Magellanic Cloud Planetary Nebula N66: Quantitative Analysis of Its WN-Type Spectrum
Hamann, W. -R.; Koesterke, L.; Torres-Peimbert, S. +5 more
Hubble Space Telescope, IUE, and ground-based observations of the central star of the LMC planetary nebula N66 (CS N66), obtained in different epochs, are presented. Since 1990, CS N66 has displayed remarkable short- and long-term spectroscopic and photometric changes amounting to more than 3 mag in the optical. Expanding model atmospheres have be…
Spatially Resolved Spectra of V1974 Cygni (Nova Cygni 1992) with the Goddard High Resolution Spectrograph
Shore, Steven N.; Hauschildt, Peter H.; Starrfield, Sumner +1 more
We report the observation of spatially resolved low-resolution GHRS spectra of the shell of the bright Galactic ONeMg nova Cygni 1992. The spectra were obtained in 1995 September, after the X-ray turnoff of the nova. We have determined the dynamical structure of the ejecta and show the evolution of the ionization within the ejecta. Abundance limit…
The High-Redshift Radio Galaxy MRC 0406-244
McCarthy, Patrick J.; Persson, S. E.; Athreya, Ramana M. +1 more
We present HST and ground-based multiwavelength observations of the distant radio galaxy MRC 0406-244. Ground-based visible and near-IR images reveal two distinct components that are aligned with the radio source axis. One of these has the red optical-to-IR and blue UV colors characteristic of radio galaxies, while the other is red in all colors. …
Gamma-Ray Burster Counterparts: Hubble Space Telescope Blue and Ultraviolet Data
Schaefer, Bradley E.; Cline, Thomas L.; Hurley, Kevin C. +1 more
The surest solution of the gamma-ray burst (GRB) mystery is to find an unambiguous low-energy quiescent counterpart. However, to date no reasonable candidates have been identified in the X-ray, optical, infrared, or radio ranges. The Hubble Space Telescope (HST) has now allowed for the first deep ultraviolet searches for quiescent counterparts. Th…
LH 72, the Center of Constellation III
Hodge, Paul W.; Wilcots, Eric M.; Olsen, Knut A. G. +1 more
Ultraviolet spectroscopy with IUE is combined with optical photometry to study the brightest blue members of the LMC OB association LH 72. LH 72 lies near the geometric center of Shapley's Constellation III, a complex of gas and stars that makes up one of the largest known superbubbles. Ages for the stars range from 5 × 106 to 1.5 × 10<…
The Detection of the λ2175 Feature and Further Analysis of the Broad Absorption Line Profile Structure in the Gravitational Lens Candidate UM 425
Kazanas, Demosthenes; Falco, Emilio E.; Michalitsianos, Andrew G. +1 more
We obtained Multiple Mirror Telescope spectra of the gravitational lens candidate UM 425 to compare the redshifts and line profile structures of lens components A and B, which are separated by approximately 6.5". The C IV λ1550 emission in both A and B exhibits broad absorption line (BAL) structure, consistent with the earlier detection of BAL str…
Simultaneous Spectroscopy and Imaging of the Jovian Aurora with the Hopkins Ultraviolet Telescope and the Hubble Space Telescope
Wolven, Brian C.; Feldman, Paul D.; Strobel, Darrell F. +4 more
Simultaneous ultraviolet spectra and images of the north polar aurora of Jupiter were obtained on 1995 March 9 with the Hopkins Ultraviolet Telescope (HUT) and the Hubble Space Telescope (HST). This unique data set contains a well-calibrated flux measurement that includes all of the H2 Lyman and Werner band emission from 900 to 1650 Å, …
Evidence for an Anomalous State in the Black Hole Candidate 4U 1630-47
Kuulkers, Erik; van der Klis, Michiel; Parmar, Arvind N.
We have reanalyzed two EXOSAT medium-energy observations during part of the 1984 X-ray outburst of the black hole candidate transient system 4U 1630-47. One observation (May 10) shows fast-timing properties (on timescales shorter than ~250 s) typical of those of other black hole candidates in their high states. The power spectrum shows a power law…
Dynamic Processes in Be Star Atmospheres. VI. Simultaneous X-Ray, Ultraviolet, and Optical Variations in λ Eridani
Smith, Myron A.; Corcoran, M. F.; Murakami, T. +4 more
We document the results of simultaneous wavelength monitoring of the B2e star λ Eri. This campaign was carried out from ground stations and with the ROSAT, ASCA, IUE, and Voyager 2 space platforms during a week in 1995 February-March a smaller follow-up was conducted in 1995 September. During the first of these intervals λ Eri exhibited extraordin…
Chromospheric Emission in Metal-poor Solar-Type Stars
Schrijver, Carolus J.; Peterson, Ruth C.
Cool stars like the Sun show chromospheric activity, which is largely attributed to nonradiative sources of energy linked to rotationally driven magnetic fields. However, a nonmagnetic process, such as dissipation of acoustic waves, may operate side by side with the first process. We report detections of chromospheric emission reversals in Mg II 2…