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Hubble Space Telescope and Ground-based Observations of I Zw 1 and Mrk 486 and the Variability of Polarization in Radio-quiet Active Galactic Nuclei
Hines, Dean C.; Schmidt, Gary D.; Smith, Paul S. +1 more
Hubble Space Telescope UV spectropolarimetry and new ground-based optical observations of the Seyfert 1/QSO I Zw 1 and highly polarized Seyfert 1 Mrk 486 are presented. I Zw 1 is found to be a polarimetric variable. Our data show that the polarization position angle has changed by ~50° compared to measurements obtained 10-15 yr ago. There is evide…
Potential Measurement of the Luminosity Function of 158 Micron [C II] at High Redshifts: A Test of Galaxy Formation Models
Stark, Antony A.
Galaxy formation scenarios predict a burst of star formation in normal galaxies at a redshift between z ~ 2 and z ~ 6 (e.g., Katz & Gunn 1991); such a starburst may be accompanied by a significant brightening of the λ = 158 µm line of C+. Galaxies that will evolve to a total luminosity L* = 5 × 1010 L
Far-Infrared Spectroscopy of Planetary Nebulae with the Kuiper Airborne Observatory
Rubin, Robert H.; Haas, Michael R.; Colgan, Sean W. J. +2 more
We present new far-infrared line observations of the planetary nebulae (PNs) NGC 7027, NGC 7009, and NGC 6210 obtained with the Kuiper Airborne Observatory (KAO). The bulk of our data are for NGC 7027 and NGC 7009, including [Ne V] 24 µm, [O IV] 26 µm, [O III] (52, 88) µm, and [N III] 57 µm. Our data for [O III] (52, 88) an…
Hubble Space Telescope Ultraviolet Spectroscopy of Two Hot White Dwarfs
Barstow, M. A.; Holberg, J. B.; Lanz, T. +1 more
We have obtained Hubble Space Telescope high-dispersion spectroscopy of two hot white dwarfs using the Goddard High-Resolution Spectrograph. The stars were selected on the basis of EUV flux as examples of H-rich DA stars containing high and low levels of short-wavelength opacity. The high-opacity star, REJ 1614-085, possesses strong features due t…
Macromolecules, Very Small Grains, and Large Dust Particles in the Whirlpool Galaxy M51 and Its Companions: A Unified View
Sauvage, Marc; Elmegreen, Bruce G.; Stockton, Alan +1 more
A combined image using optical and mid-infrared ISOCAM data of the galaxy M51 and its companion reveals a unified view of the distribution of dust grains of all sizes. The image shows the large grains in extinction at blue light and the small grains in emission at 15 µm. Much of the emission from small grains coincides with extinction from l…
Accretion and UV Variability in BP Tauri
Gómez de Castro, Ana I.; Franqueira, M.
BP Tau is one of the few classical T Tauri stars for which the presence of a hot spot in the surface has been reported without ambiguity. The most likely source of heating is gravitational energy released by the accreting material as it shocks with the stellar surface. This energy is expected to be radiated mainly at UV wavelengths. In this work w…
Third Interplanetary Network Localization, Time History, Fluence, Peak Flux, and Distance Lower Limit of the 1997 February 28 Gamma-Ray Burst
Frontera, F.; Orlandini, M.; Cline, T. +9 more
The gamma-ray burst of 1997 February 28 was localized using the arrival time analysis method with the Ulysses, BeppoSAX, and WIND spacecraft. The result is a +/-31.5" (3 σ) wide annulus of possible arrival directions that intersects both the position of the burst determined independently by the BeppoSAX Wide Field Camera and the position of a fadi…
Charge Transfer between Neutral Atoms and Highly Ionized Species: Implications for ISO Observations
Korista, K. T.; Ferland, G. J.; Dalgarno, A. +1 more
We estimate rate coefficients for charge transfer between neutral hydrogen and helium and moderately to highly ionized heavy elements. Although charge transfer does not have much influence on hot collisionally ionized plasmas, its effects on photoionized plasmas can be profound. We present several photoionization models that illustrate the signifi…
Detection of Self-reversed Lyα Lines from the Jovian Aurorae with the Hubble Space Telescope
Ballester, Gilda E.; Prangé, Renée; Clarke, John T. +5 more
We present Lyα profiles taken at high spectral resolution (~70 mÅ) in the Jovian aurorae, using the Goddard High-Resolution Spectrograph aboard the Hubble Space Telescope. They exhibit a strong central reversal, reminiscent of solar and stellar spectra. This effect was predicted by models as a consequence of radiative transfer effects on photons e…
Laboratory Identification of Temperature Diagnostic Si VII and S IX Lines Present in the Solar Coronal Spectra Measured by SUMER/SOHO
Schühle, U.; Feldman, U.; Laming, J. M. +3 more
The solar coronal spectrum between 500 and 1610 Å and at a height of 21,000 km above the west equatorial limb has recently been recorded by the SUMER instrument on SOHO. Using laboratory spectra obtained with the beam-foil technique, we report the identification of 32 lines observed in this spectrum as 2s22p33s-2s2…