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HST observations of three radio galaxies at redshift z~=1
Best, P. N.; Rottgering, H. J. A.; Longair, M. S.
The first results of a programme to image a sample of radio galaxies at redshift z~=1 with the Hubble Space Telescope are reported in this Letter. The images of the three galaxies presented here (3C368, 3C324 and 3C265) show a wealth of fine structure down to the resolution limit of the HST. All three systems show a clear alignment of the optical …
Circinus X-1 revisited: fast-timing properties in relation to spectral state.
van Paradijs, J.; van der Klis, M.; Lewin, W. H. G. +2 more
We have studied the X-ray spectral and fast-timing variations of Cir X-1 by performing a homogenous analysis of all EXOSAT ME data on this source using X-ray hardness-intensity diagrams (HIDs), colour-colour diagrams (CDs), and power spectra. Cir X-1 exhibits a wide range of power spectral shapes and a large variety in X-ray spectral shapes. At di…
Ulysses Above the Sun's South Pole: An Introduction
Smith, Edward J.; Marsden, Richard G.; Page, D. Edgar
Ulysses has explored the field and particle environment of the sun's polar region. The solar wind speed was fast and nearly constant above -50^circ latitude. Compositional differences were observed in slow (low-latitude) solar wind and in fast (high-latitude) solar wind. The radial magnetic field did not change with latitude, implying that polar c…
Detection of the Hot White Dwarf in the Magnetic Nova V1500 Cygni with the Hubble Space Telescope
Liebert, James; Schmidt, Gary D.; Stockman, H. S.
A comprehensive investigation of the AM Herculis-like nova system V1500 Cyg is presented, featuring time-resolved spectrophotometry with the Faint Object Spectrograph (FOS) of the Hubble Space Telescope (HST), coeval optical circular spectropolarimetry and spectrophotometry, and new broadband polarimetry. A revised ephemeris for the rotating white…
Preliminary link of the HIPPARCOS and VLBI reference frames
Lindegren, L.; Mignard, F.; Lestrade, J. -F. +12 more
We present a comparison of VLBI and Hipparcos astrometric parameters of several optically bright radio-emitting stars. The systematic discrepancies found in these preliminary data can be removed by performing a single global rotation between the extragalactic and Hipparcos reference frames. Two estimates of this rotation and its time derivative ha…
Discovery of Highly Ionized High-Velocity Clouds toward Markarian 509
Sembach, Kenneth R.; Savage, Blair D.; Lu, Limin +1 more
We present Goddard High Resolution Spectrograph measurements of the Milky Way halo gas absorption toward Mrk 509 (1 = 36°.0, b = -29°.9) in the 1233-1268 and 1521-1558 Å spectral regions at a resolution of ≈15 km s-1. We detect high-velocity (υLSR -340 to -170 km s-1 absorption in both members of the C IV λλ1548, 1…
Quasar Lyman Edge Regions in Polarized Light
Antonucci, R. R. J.; Kinney, A. L.; Bushouse, H. +2 more
The standard paradigm of energy production in quasi-stellar objects (QSOs) includes an accretion disk surrounding a supermassive black hole. Two important consequences of such a disk are a feature, probably in absorption, at the Lyman edge, and significant polarization parallel to the disk plane at most viewing angles. The polarization signature c…
The IUE MEGA Campaign: Wind Structure and Variability of HD 50896 (WN5)
Willis, A. J.; Moffat, A. F. J.; Marchenko, S. V. +2 more
We present preliminary results from an extensive study of UV line and continuum variability in the WN5 star HD 50896 = EZ CMa, monitored over 16 consecutive days in 1995 January, as part of the IUE "MEGA" campaign. Although variations are seen in all the major emission lines, the clearest occur in the unsaturated, subordinate N IV lambda 1718 line…
A Test of Galaxy Evolutionary Models via Angular Sizes
Casertano, Stefano; Im, Myungshin; Tyson, J. Anthony +2 more
The relationship between angular size, magnitude, and redshift of faint galaxies is explored as a potential tool to distinguish between different galaxy evolutionary models. Different models, based on merging, mild luminosity evolution, and no evolution, lead to different predictions of the angular size distribution, redshift-size relation, and ma…
The electron temperature in the inner coma of comet P/Halley.
Eberhardt, P.; Krankowsky, D.
From the CH_3_OH_2_^+^/H_3_O^+^ and H_3_O^+^/H_2_O^+^ ratios measured by the Giotto Neutral Mass Spectrometer in the inner coma (distance <20000km) of comet P/Halley we derive two independent electron temperature profiles. They agree very well and the electron temperature T_e_ increases gradually from =~100K at 2000km to =~900K at 8500km follow…