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GHRS Observations of Cool, Low-Gravity Stars. II. Flow and Turbulent Velocities in the Outer Atmosphere of gamma Crucis (M3.4 III)
Judge, Philip G.; Robinson, Richard D.; Carpenter, Kenneth G.
The Goddard High Resoulution Spectrograph (GHRS) on the Hubble Space Telescope (HST) has been used to obtain medium (R = 20,000) and high (R = 85,000) resoultion UV spectra of chromosphere emission features for the M3.4 III star gamma Cru. Small Science Aperture (SSA) G270M and Echelle-B spectra of selected regions in the 2300-2850 A range were ob…
Broad NE VIII lambda 744 Emission from the Quasar PG 1148+549
Hamann, Fred; Shields, Joseph C.; Ferland, Gary J. +1 more
We discuss the probable detection of broad Ne VIII λ774 emission from the zɛ = 0.978 quasar PG 1148+549, and we use spectral synthesis calculations to study the physical conditions in the line-forming gas. The theoretical predictions and the measured line wavelength both support Ne VIII λ774 as the most likely identification.
Our c…The Complex Optical to Soft X-Ray Spectrum of Low-Redshift Radio-quiet Quasars. II. Comparison with Free-Free and Accretion Disk Models
Elvis, Martin; Wilkes, Belinda J.; McDowell, Jonathan C. +3 more
We compare the optical to soft X-ray spectral energy distributions (SEDs) of a sample of bright low-redshift (0.048 < z < 0.155), radio-quiet quasars, with a range of thermal models which have been proposed to explain the optical/UV/soft X-ray quasar emission: (1) optically thin emission from an ionized plasma, (2) optically thick emission f…
Atomic Physics with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope. I. Oscillator Strengths for Neutral Sulfur
Federman, S. R.; Cardelli, Jason A.
Interstellar spectra toward ζ Oph acquired with the Goddard High-Resolution Spectrograph were used to obtain oscillator strengths for approximately two dozen S I lines. This analysis was possible because precisely determined experimental oscillator strengths are available for several multiplets, including one with a weak interstellar line. The sel…
Optical Structure and Polarization of the Western Hot SPOT of Pictor A
Crane, P.; Mackay, C. D.; Thomson, R. C.
HST images of the western hot spot of the nearby FR II radio galaxy Pictor A resolve the hot spot into an amorphous region of highly polarized wisps. The high polarization (≳50%) indicates that the optical emission is synchrotron radiation and that the magnetic field structure has been well resolved. The magnetic field is oriented nearly perpendic…
High-Resolution Ultraviolet Spectroscopy of Jupiter's Aurora with the Hubble Space Telescope
Caldwell, J. J.; Fox, J. L.; Kim, Y. H.
In 1993 June and July, we obtained 18 spectra of Jupiter's aurora in the wavelength range 1586-1620 Å using the Goddard High Resolution Spectrograph on board the Hubble Space Telescope (HST). The field of view for each observation was 2" × 2". There were 14 spectra of the northern and four spectra of the southern auroral ovals. The spectra are dom…
Stellar Variability in the Central Populations of 47 Tucanae from WF/PC Observations with the Hubble Space Telescope. I. Project Overview, Reduction Techniques, and First Results
Gilliland, Ronald L.; Saha, Abhijit; Shara, Michael M. +2 more
Stars in the central region of the dense globular cluster 47 Tucanae were monitored for variability using time-resolved photometry from 99 Hubble Space Telescope Planetary Camera exposures of 1000 s in the F336W (U) filter. The observations were obtained while 47 Tuc was in the continuous viewing zone (CVZ) of HST. This data set provides an unpara…
A Study of the Chromospherically Active, Short-Period Binary VZ PISCIUM
Lu, Wenxian; Guinan, Edward F.; Hrivnak, Bruce J.
The short-period binary VZ Piscium is unusual in that it has a high space velocity, indicating that it is old, and a high mass ratio, suggesting that it is presently evolving into contact with little mass exchange having occurred between the components. In this study, we obtained lUE and visible spectra to investigate Mg II h + k and Ca II H and K…
Interpretation of Anomalous Ultraviolet Transitions of Fe II Observed in Laboratory Fourier Transform Spectra and Stellar HST and IUE Spectra
Johansson, Sveneric; Wahlgren, Glenn M.; Brage, Tomas +2 more
We discuss LS-forbidden ΔS = 2 transitions of Fe II that appear as strong lines in ultraviolet stellar and laboratory spectra. The lines occur because of indirect level mixing-two close energy levels, W2P3/2 and x6P3/2, are mixed through a third level acting as a catalyst. In transition multiplets, that …
Transition Probabilities for the UV0.01 Multiplet in N III
Judge, Philip G.; Brage, Tomas; Fischer, Charlotte Froese
We report on large-scale ab initio multiconfiguration Hartree-Fock calculations for the UV0.01 multiplet, 2s22p2PJ - 2s2p2 4PJ prime, in N III. The resulting transition probabilities agree very well with recent semiempirical calculations, and the lifetimes for two of the three upper levels agr…