Search Publications
High-Velocity Plasma in the Transition Region of AU Microscopii: Evidence for Magnetic Reconnection and Saturated Heating during Quiescent and Flaring Conditions
Wood, Brian E.; Linsky, Jeffrey L.
We analyze high-resolution HST spectra of the dMOe flare star AU Mic, including the profiles of the C IV 1548.2 A, 1550.8 A and Si IV 1393.8 A, 1402.8 A lines obtained with the G160M grating of the Goddard High-Resolution Spectrograph. The quiescent profiles of the C IV and Si IV lines are broad, and not simple Gaussians in shape. Flux in the C IV…
High-Resolution Spectra of Jupiter's Northern Auroral Ultraviolet Emission with the Hubble Space Telescope
Trafton, L. M.; Gerard, J. C.; Munhoven, G. +1 more
The first spectroscopic observations of planetary aurora with the Hubble Space Telescope (HST) are reported. These include spectral regions centered on the H2 Lyman and Werner bands of a region of Jupiter's northern aurora. The observations were made with the Goddard High Resolution Spectrograph (GHRS) using the Large Science Aperture as part of a…
Elemental Abundances of the Supernova Remnant G292.0+1.8: Evidence for a Massive Progenitor
Singh, K. P.; Hughes, John P.
We present a comprehensive nonequilibrium ionization (NEI) analysis of X-ray spectral data from the Einstein Observatory and EXOSAT for the supernova remnant G292.0+1.8. The spectra are well described by a single-temperature, single-timescale NEI model with kT = 1.64-0.19+0.29 keV and net = (5.55-1.12
Probing the Galactic Disk and Halo. I. The NGC 3783 Sight Line
Sembach, Kenneth R.; Savage, Blair D.; Lu, Limin
We report a study of Galactic disk and halo absorption toward the Seyfert galaxy NGC 3783 which has Galactic coordinates l = 287.46 and b = +22.95. The data were obtained with the Goddard High Resolution Spectrograph operating at medium resolution with the Large Science Aperture, which produces a line spread function having a sharp core (FWHM ~ 20…
GHRS Observations of Cool, Low-Gravity Stars. I. The Far-Ultraviolet Spectrum of alpha Orionis (M2 Iab)
Brown, Alexander; Robinson, Richard D.; Linsky, Jeffrey L. +2 more
We present far-UV (1200-1930 A) observations of the prototypical red supergiant star alpha Ori, obtained with the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST). The observations, obtained in both low- (G140L) and medium- (G160/200M) resolution modes, unambiguously confirm that the UV 'continuum' tentatively seen w…
A Dwarf Nova in the Core of 47 Tucanae
Paresce, Francesco; de Marchi, Guido
The Faint Object Camera on the Hubble Space Telescope detected an outburst of a star (V2) located in the core of the Galactic globular cluster 47 Tucanae that occured in 1993 October. The instrumental magnitudes at 220 and 342 nm at outburst were 15.4 and 16.2, respectively. Observations of the same object made a year before and 2 weeks later gave…
IUE Spectra and Photoionization Models of the Seyfert 2 Galaxies NGC 7674 and I ZW 92
Crenshaw, D. Michael; Wu, Chi-Chao; Harrington, J. Patrick +1 more
The physical conditions in the narrow-line regions of two Seyfert 2 galaxies, NGC 7674 and I Zw 92, are examined using IUE spectra, published optical spectra and multifrequency observations, and photoionization models. For each Seyfert galaxy, the emission-line fluxes were dereddened using the He II λ1640/λ4686 ratio. Photoionization models were c…
A Hubble Space Telescope Ultraviolet Spectrum of SN 1993J
Filippenko, Alexei V.; Pun, Chun S. J.; Fransson, Claes +10 more
We obtained a Hubble Space Telescope ultraviolet spectrum of the Type II supernova SN 1993J in M81 on 1993 April 15. The ~1650-2900 A region is smoother than observed for SN 1987A and SN 1992A and lacks strong P Cygni absorptions caused by iron peak element lines. Synthetic spectra calculated using a parameterized LTE procedure and a simple model …
Modeling and Interpretation of the Optical and HST UV Spectrum of SN 1993J
Hauschildt, P. H.; Baron, E.; Branch, D.
We present spherically symmetric, non-LTE, expanding model atmosphere synthetic spectra of SN 1993J and compare them to the ultraviolet and optical spectra obtained simultaneously on 1993 April 15 by the HST and at Lick Observatory. We are able to fit the optical and HST near-UV spectra with a variety of compositions, but find that our best fits a…
A Large, Periodic Variation in the Stellar Wind of theta 1 Orionis C
Walborn, Nolan R.; Nichols, Joy S.
A period of 15.4 days, recently discovered by Stahl et al. from intensive monitoring of hydrogen alpha emission in Theta1 Ori C during 1992-1993, has been found to phase large variations in the C IV lambda lambda 1548, 1551 wind profile of this star previously reported from International Ultraviolet Explorer (IUE) high-resolution data o…