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The broad line region of narrow-line Seyfert 1 galaxies.
Mas-Hesse, J. M.; Rodriguez-Pascual, P. M.; Santos-Lleo, M.
We have analyzed new and archival IUE observations of narrow-line Seyfert 1 galaxies (NLS1) in order to revise the ultraviolet (UV) properties of this sub-group of Active Galactic Nuclei (AGN). We have found broad wings in the strongest UV emission lines, ruling out the hypothesis that there is no broad line emission region in this type of objects…
Evidence of a Thermonuclear Runaway and Proton-Capture Material on a White Dwarf in a Dwarf Nova
Szkody, Paula; Sion, Edward M.; Hubeny, Ivan +3 more
We present Hubble Space Telescope Goddard High-Resolution Spectrograph G160M spectra of the white dwarf in VW Hydri, exposed during quiescence, 1 month after the end of a normal dwarf nova outburst. Our spectra, covering the wavelength interval 1236-1272 Å, were obtained at orbital phase 0.06-1.60 they reveal strong photospheric Si II λλ1260, 1265…
Hubble Space Telescope Observations of the Middle-aged Pulsar 0656+14
Córdova, F. A.; Pavlov, G. G.; Welty, A. D.
Multiwavelength spectral observations of middle-aged (τ~104-106 yr) isolated pulsars enable one in principle to separate thermal radiation emitted from the neutron star surface and nonthermal radiation from its magnetosphere. We have previously detected the middle-aged radio and soft X-ray pulsar 0656+14 with the Hubble Space…
A jet-cloud interaction in 3C 34 at redshift z=0.69
Best, P. N.; Rottgering, H. J. A.; Longair, M. S.
We report the detection of a strong jet-cloud interaction at a distance of 120 kpc from the nucleus of the radio galaxy 3C 34, which has redshift z=0.69. Hubble Space Telescope images of the radio galaxy show a long narrow region of blue emission orientated along the radio axis and directed towards a radio hotspot. The William Herschel Telescope h…
The Shock and Extended Remnant around the Crab Nebula
Hester, J. Jeff; Sankrit, Ravi
The [O III] ``skin'' around the Crab Nebula was shown by Hester et al. to be the Rayleigh-Taylor (R-T)-unstable interface between the synchrotron nebula and swept-up ejecta from the supernova explosion. Unlike the bright photoionized filaments, this skin is most easily understood as the cooling region behind a shock driven into an extended remnant…
The Abundance of Mg in the Interstellar Medium
Fitzpatrick, Edward L.
An empirical determination of the f-values of the far-UV Mg II λλ1239, 1240 lines is reported. The strong near-UV Mg II λλ2796, 2803 lines are generally highly saturated along most interstellar sight lines outside the local interstellar medium (ISM) and usually yield extremely uncertain estimates of Mg+ column densities in interstellar …
The modelling of the latitude dependence of cosmic ray protons and electrons in the inner heliosphere
Potgieter, M. S.; Heber, B.; Ferrando, P. +1 more
Observations during the fast latitude scan of Ulysses show that the latitude dependence of cosmic ray protons is significantly less than predicted by drift models which were based on the Parker geometry for the heliospheric magnetic field (HMF) and diffusion coefficients ~ 1/B_p. Recent modeling with a modified HMF and enhanced turbulence in the p…
Damped Lyalpha Absorption Associated with an Early-Type Galaxy at Redshift z=0.16377.
Meyer, David M.; Chen, Hsiao-Wen; Savaglio, Sandra +8 more
We report new HST and ground-based observations of a damped Lyα absorption system toward the QSO 0850+4400. The redshift of the absorption system is ζ=0.l63770±0.000054 and the neutral hydrogen column density of the absorption system is log N=19.81±0.04 cm-2. The absorption system is by far the lowest redshift confirmed damped Lyα absor…
Pulsations and Accretion Geometry in YY Draconis: A Study Based on Hubble Space Telescope Observations
Thorstensen, John R.; Hellier, Coel; Haswell, Carole A. +2 more
We present 1 Å resolution fast ultraviolet spectroscopy of YY Dra, coordinated U, B, V, R, and I photometry, and Hα spectroscopy. The UV continuum is strongly pulsed: we found 16% semiamplitude pulses with period 264.7(1) s; there was no evidence for power at twice this period. The UBV pulses are in phase with the UV continuum pulsation. A color t…
The Hourglass Nebulae of Sher 25 and SN 1987A: Two of a Kind? 1
Grebel, Eva K.; Brandner, Wolfgang; Chu, You-Hua +2 more
We have performed a detailed study of the morphology and kinematics of the hourglass-shaped nebula around the blue supergiant Sher 25 in the galactic giant H II region NGC 3603. Near-infrared high-resolution adaptive optics images in the Br gamma line and HST/NICMOS images in the He I 1.08 mu m line were compared with isovelocity maps in the H alp…