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Massive Stars in Starburst Galaxies and the Origin of Galactic Superwinds.

Leitherer, C.

Soft and hard X-ray observations of 4U 1626-67

Mavromatakis, F.

The accreting binary pulsar 4U 1626-67 was detected in the soft X-rays by ROSAT in the course of the All-Sky survey at an average luminosity of 1.5 x 10^35^ d^2^_5 kpc_ erg/s, the lowest observed so far. The ROSAT spectrum is better fitted by a bremsstrahlung model rather than a blackbody spectrum. The source spectrum appears to be absorbed by a c…

Ultraviolet Observations of the Gamma-Ray Blazar 3C 279 following the Gamma-Ray Flare of 1991 June

Vestrand, W. Thomas; Bonnell, Jerry T.; Stacy, J. Gregory

Ultraviolet observations of the gamma-ray blazar 3C 279 were carried out in 1991 July with the International Ultraviolet Explorer (IUE) satellite, 28 days after the outburst of intense gamma-ray emission detected from this source with the high-energy EGRET instrument aboard the Compton Gamma-Ray Observatory. IUE observations were conducted over th…

Geometry of the Hubble Space Telescope Wide Field/Planetary Camera Field

Gould, Andrew; Yanny, Brian

We present a solution for the relative positions and orientations of the four CCD chips on the Hubble Space Telescope (HST) Planetary Camera (PC). An accurate solution is required when matching HST images with ground-based images or with one another. The solution is accurate to about 2/3 PC pixel or about 0.03", a 10-fold improvement over the best…

HST observations of 3C 449: discovery of an extended nuclear disk and of possible optical jets.

Capetti, A.; Sparks, W. B.; Macchetto, F. +1 more

We present the results of HST observations of the radio-galaxy 3C 449. Observations were taken with the Faint Object Camera using the F372M and F342W filters both of which include the redshifted [OII]λλ3726, 3729 lines. Around the nucleus of 3C 449, we detected a ring with a projected diameter of 0.4" which corresponds to about 200 pc. Our analysi…

Observational Features of Cosmic Gamma-Ray Bursts: Evidence for Galactic versus Extragalactic Origin

Hurley, Kevin

The recent observational data on gamma-ray bursts are reviewed. Burst time histories display features at the millisecond level which suggest a compact object origin. Lines in the energy spectra and spectral evolution point toward a Galactic neutron star origin, even though line features have not yet been confirmed in recent data. The Galactic dist…

Satellite Emission Features in Two Seyfert Galaxies: New Evidence That Radio- Quiet AGN Possess Subrelativistic Winds

Stocke, John T.; Sachs, Elise R.; Shull, Michael +1 more

HST/FOS spectra are presented for three bright Seyfert galaxies including one (PG 1351+64) which possesses blue-displaced absorption features in C IV, Si IV, N V, and Lyα (but not in Mg Il) similar to those seen at high redshift in the broad-absorption-line (BAL) QSOs. Several features of the absorptions in PG 1351+64, including variability seen i…

The winds of hot, close binaries. Paper 1: Y Cygni (HD 198846)

Stickland, D. J.; Pachoulakis, I.; Koch, R. H. +1 more

MG II Chromospheric-Emission Dating of HR 1614 Moving-Group Stars

Smith, Graeme H.; Hufnagel, Beth

A 2800 A Mg II line index (Mg II) that is sensitive to chromospheric activity has been measured from International Ultraviolet Explorer spectra of a sample of eight HR 1614 moving-group dwarfs. All of these dwarfs have values of I(Mg II) indicative of ages >= 3 Gyr. The relatively old ages of these dwarfs, togther with their similar and peculia…

A Deep Atmospheric Eclipse of AL Velorum

Eaton, J. A.

I have obtained new International Ultraviolet Explorer (IUE) observations in 1992 to search for an accretion column in and to analyze an atmospheric eclipse of AL Vel, a low luminosity zeta Aurigae binary. Rich shell spectra recorded at three phases of atmospheric eclipse give column densities and excitation temperatures for the chromospheric gas.…