Search Publications
A Prediction of the gamma -Ray Flux from Nova Herculis 1991
Truran, James W.; Shore, Steven N.; Sonneborn, George +3 more
UV observations made with the IUE satellite of Nova Her 1991 are presented and discussed. A distance of 3.4 kpc and reddening of 0.6 E(B-V) to Nova Her 1991 are determined by comparing its UV and optical outburst behavior with those of the extragalactic ONeMg nova LMC 1990 No. 1. Her 1991 was also detected by Rosat five days into its outburst, and…
The Nature of the Recurrent Nova T Coronae Borealis: Ultraviolet Evidence for a White Dwarf Accretor
Cassatella, Angelo; Gilmozzi, Roberto; Selvelli, Pier L.
Data from eleven years of IUE observations of T CrB during its quiescent phase suggest that a white dwarf accretor rather than a main-sequence star is the hot component of the system. The spectroscopic and photometric behavior of T CrB during the 1946 outburst actually supports the interpretation of a thermonuclear runaway event on a massive white…
Evolving, Dynamical Models for Collapsed-Core Globular Clusters: M15 and NGC 6624
Cohn, Haldan N.; Lugger, Phyllis M.; Murphy, Brian W. +1 more
The stellar populations of the collapsed-core globular clusters M15 and NGC 6624 are investigated by fitting observed surface-brightness and projected velocity-dispersion profiles. The present evolving cluster models were generated by the direct Fokker-Planck method and incorporate realistic stellar mass spectra and energy input from binaries form…
Spherically Symmetric, Expanding, Non--LTE Model Atmospheres for Novae during Their Early Stages
Hauschildt, P. H.; Starrfield, S.; Wehrse, R. +1 more
In the continuum and line-blanketed models presented here, nova atmospheres are characterized by a very slow decrease of density with increasing radius. This feature leads to very large geometrical extensions so that there are large temperature differences between the inner and outer parts of the line-forming regions. The theoretical spectra show …
The SN 1986G in Centaurus A.
Schmutz, W.; Danziger, J.; Heydari-Malayeri, M. +10 more
We present photometric and spectroscopic observations of SN 1986 G, spanning up to one year after the explosion. The overall photometric behavior of this SN Ia results rather normal. The maximum at B = 1245+/-0.05 was reached on May 11,1986, then the decline to the inflection point was relatively fast (β_B_ = 12.0 mag/100 d), but similar to other …
The solar X-ray/cosmic gamma-ray burst experiment aboard ULYSSES
Cline, T.; Hurley, K.; Sommer, M. +7 more
The scientific objectives of the Ulysses solar X-ray/cosmic gamma-ray burst experiment, and the unique features of the Ulysses mission which will help to achieve them are described. After a discussion of the special design constraints imposed by the mission, the sensor systems, consisting of two CsI scintillators and two Si surface barrier detecto…
A Multiwavelength Study of Nova QU Vulpeculae 1984
Williams, Robert E.; Truran, James W.; Ferland, Gary J. +6 more
We have combined ground-based optical and satellite ultraviolet spectrophotometric data to study the ejected shell of Nova Vulpecula 1984 No. 2 (QU Vul). Substantial uncertainties concerning the nature of the ionizing continuum, and the role played by density inhomogeneities, now exist. Because of these uncertainties, the chemical composition is d…
Energetic Charged-Particle Phenomena in the Jovian Magnetosphere: First Results from the Ulysses COSPIN Collaboration
Balogh, A.; Kunow, H.; Muller-Mellin, R. +16 more
The Ulysses spacecraft made the first exploration of the region of Jupiter's magnetosphere at high Jovigraphic latitudes (~37^circ south) on the dusk side and reached higher magnetic latitudes (~49^circ north) on the day side than any previous mission to Jupiter. The cosmic and solar particle investigations (COSPIN) instrumentation achieved a rema…
Fractionation of CO in the Diffuse Clouds toward zeta Ophiuchi
Federman, S. R.; Lambert, David L.; Cardelli, Jason A. +1 more
An analysis of CO A-X bands in diffuse clouds toward Zeta Ophiuchi is presented. The results provide isotopic ratios that constitute the strongest observational evidence for highly localized isotopic fractionation of CO in diffuse portions of an interstellar cloud. The value of the fractionation implies that selective photodissociation is the cont…
Ultraviolet, Optical, and Infrared Observations of the High-Latitude Molecular Cloud toward HD 210121
Welty, Daniel E.; Fowler, James R.
Low-resolution UV spectra of the B3 V star HD 210121, located behind the high-latitude molecular cloud DBB 80, yield an extinction curve exhibiting a far-UV rise that is among the steepest known. The apparently simple line of sight affords an excellent opportunity for investigating the absorption and emission characteristics of a single, isolated …