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Seyfert Galaxies. IV. Nuclear Profiles of Markarian Seyfert Galaxies from Hubble Space Telescope Images
MacKenty, John W.; Griffiths, Richard E.; Nelson, Charles H. +1 more
We have examined the nuclear profiles of the Seyfert and non-Seyfert Markarian galaxies in our near-infrared Hubble Space Telescope WF/PC-1 snapshot survey. We find that nuclei of types 1-1.5 Seyfert galaxies are dominated by strong point sources, while those of Seyfert 2 and non- Seyfert Markarian galaxies tend to be resolved, less distinguished,…
The Ultraviolet/Optical Continuum of Hercules X-1/HZ Herculis
Cheng, F. H.; Vrtilek, S. D.
We present observations of the binary X-ray pulsar system Hercules X-1/HZ Herculis taken with the International Ultraviolet Explorer (lUE) and several ground-based observatories as part of a multi- wavelength campaign conducted in 1993 August. The 1993 campaign found the source in an unusual state, with substantially reduced X-ray flux, and also r…
The Wolf-Rayet Star HD 197406, with Its Strongly Ionizing Close Companion
Moffat, Anthony F. J.; Marchenko, Sergey V.; Tovmassian, Gaghik H. +1 more
High-quality, phase-dependent CCD spectra are presented for the first time for this unusual Population I, runaway WN7 single-line binary system. Besides confirming a previous orbit based on the N iv 4058 Å emission line, these spectroscopic data show phase-dependent, line-profile variations, especially in He II. The low mass function, but normal o…
Complex Gaseous Structure in the Nucleus of NGC 5252
Wilson, Andrew S.; Morse, Jon A.; Tsvetanov, Zlatan I. +1 more
We present several Hubble Space Telescope (HST) WFPC2 emission-;ine and continuum images of NGC 5252, a Seyfert 2 50 galaxy with a large-scale "ionization bi-cone." In the Hα + [N II] image, the nucleus is bracketed at 0"3 radii by two bright emission-line clumps along P.A. = 35° (∼20° from the major axis of the large-scale stellar disk). These th…
Observing Stellar Coronae with the Goddard High Resolution Spectrograph. II. The RS CVn Binary System HR 1099
Carpenter, K. G.; Robinson, R. D.; Airapetian, V. S. +1 more
We report time series observations of the RS CVn star HR 1099 taken with the Goddard High Resolution Spectrograph onboard the Hubble Space Telescope. The data cover a wavelength range from 1342 to 1375 Å and show a measurable continuum, as well as emission lines of O I, C I, CII, Fe II, O V, and Fe XXI. The chromospheric and transition region feat…
The Starburst Nuclear Region in M82 Compared in Several Wave Bands
Golla, Goetz; Allen, Michael L.; Kronberg, Philipp P.
We utilize new, sensitive radio continuum images of M82 at 1.5, 15 and 22 GHz for a comparison with images at other wave bands that have recently appeared in the literature. Overlays of the radio data with images in the optical V band (Hubble Space Telescope observations), mid- infrared, the [Ne II] line, and the CO (1 - 0) and the HCN line are pr…
Strong Clustering in the Low-Redshift Ly alpha Forest
Ulmer, Andrew
The two-point correlation function, ξ, of Lyα forest is found to be large, ξ = 1.8^+1.6^_-1.2_, greater than 90% confidence level, on the scale of 250-500 km s^-1^ for a sample of absorbers (0 < z < 1.3) assembled from Hubble Space Telescope Key Project Observations. This correlation function is stronger than at high redshift (z > 1.7) wh…
High-Velocity Gas in GHRS Spectra of Three OB Stars
York, D. G.; Welty, D. E.; Lauroesch, J. T. +4 more
In Hubble Space Telescope (HST) GHRS spectra of the B1 V star 23 Ori, we observed interstellar absorption lines of C II, C 11*, Mg II, Al II, Al III, Si II, Si III, and S II at a heliocentric radial velocity of about -100 km s-1. Lines of N I, O I, and Fe II that normally are strongly saturated in low-velocity interstellar ga…
The ROSAT-PSPC Spectrum of Bright Low-z Quasars
Molendi, S.; Ulrich-Demoulin, M. -H.
We present and discuss ROSAT Position Sensitive Proportional Counter (PSPC) spectra of seven bright low-redshift quasars obtained during pointed observations, including in the discussion the results previously obtained on the quasar PG 1116+215. Several pointed observations are available for two quasars. In two of our objects the count rate varied…
Sleuthing the Dynamo: Hubble Space Telescope Faint Object Spectrograph Observations of Solar-Type Dwarfs in Young Galactic Clusters
Ayres, Thomas R.; Brown, Alexander; Simon, Theodore +3 more
We have used the Faint Object Spectrograph of the Hubble Space Telescope to record the ultraviolet emissions of solar-type [(B - V)0 ∼0.6 mag] dwarf stars in young galactic clusters: five in the Hyades (t 600 Myr); three in the Pleiades (t ∼ 70 Myr); and two in αPersei (t ∼ 50 Myr). Despite high levels of scattered light in the G130H (1…