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Deep Hubble Space Telescope Imaging of a Compact Radio Galaxy at Z = 2.390
Windhorst, Rogier; Keel, William C.; Mathis, Douglas F.
We present deep 4 hr HST/WFC images in V and I of the LBDS radio galaxy 53W002, a weak and compact narrow-line galaxy recently discovered at z = 2.390. After deconvolution, the resolution is 0.2" FWHM. Its I- band structure is quite compact with 30% +/- 10% of its flux in the central <~ 1 kpc, presumably from its AGN. This is surrounded by a cl…
The Broad Emission-Line Profiles and Profile Variability of the Seyfert 1 Galaxy Arakelian 120
Korista, Kirk T.
We present Hα and Hβ broad emission-line profiles of the Seyfert galaxy Arakelian 120 from the past ~10 yr, representing over 100 spectroscopic observations. The broad emission-line profiles of the Balmer lines are complex in structure and variable; the profile variations themselves are complex. We attempt to isolate separate emitting components w…
Variability of Emission Lines in the Planetary Nebulae IC 4997 and NGC 6572
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H.
We compare the new IUE high dispersion data and recent ground-based spectra of the planetary nebulae IC 4997 and NGC 6572 with equivalent IUE observations taken in 1980 and optical data taken in 1974-1990. Significant changes are detected in many emission line fluxes in IC 4997, and primarily in He II and C IV for NGC 6572. We interpret these chan…
Highly Ionized Atoms toward HD 93521
Fitzpatrick, Edward L.; Spitzer, Lyman, Jr.
Results are reported from the HST High Resolution Spectrograph observations of absorption features of C IV and Si IV in the spectrum of the high-latitude O star HD 93521 (l = 183 deg; b = 62 deg). A comparison of Si IV and C IV profiles showed that the FWHM of both features is about 50 km/sec, in contrast to the 7 km/sec found for one of the sever…
Studies of symbiotic stars. VI. The eclipsing symbiotic nova AS 338.
Munari, U.
The nature and evolution of AS 338 is investigated. An extensive new set of photometric and spectrophotometric/UE, optical and IR data is presented, covering the period 1962-1991. It is found that AS 338 is a symbiotic nova that entered the outburst phase in late 1981. The outburst, far to be concluded, has been large in amplitude and of long dura…
Resolution and Noise Properties of the Goddard High Resolution Spectrograph
Ebbets, Dennis C.; Morris, Simon L.; Gilliland, Ronald L. +2 more
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST) provides an unprecedented capability for ultraviolet spectroscopy of a wide range of astronomical targets. The combination of high resolution (to R 100,000), good sensitivity (maximum total system quantum efficiency of 1%), low background noise (order 0.01 counts s…
Ulysses: Interplanetary shocks between 1 and 4 AU
Balogh, A.; Forsyth, R. J.; Burton, M. E. +3 more
The complex solar events of March 1991 are evident as a large increase in the rate of occurrence of interplanetary shocks. Using Ulysses magnetic field and plasma measurements, 32 forward shocks and 7 reverse shocks have been identified in the 280 day interval from October 26, 1990 to August 1, 1991. The March events alone have produced 9 shocks, …
Low frequency magnetic signals associated with Langmuir waves
Balogh, A.; Goetz, K.; Forsyth, R. J. +4 more
With the URAP experiment on Ulysses, we have observed low frequency signals with a magnetic component in close time correlation with electrostatic Langmuir waves at the plasma frequency. In most, if not all, of these cases, the Langmuir waves are part of a Type III solar burst. We investigate this effect and show that the low frequency waves are i…
Non-LTE line formation for iron group elements.
Butler, K.; Becker, S. R.
A non-LTE line formation calculation for Fe v is introduced. The data for radiative bound-bound transitions which have been derived as part of this work are described and their accuracy is evaluated. The theoretical non-LTE spectrum of Fe v is compared to the HST spectrum of the sdO star BD + 75 deg 325 resulting in a determination of the iron abu…
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…