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The radial distribution of galactic gamma rays. II - The distribution of cosmic-ray electrons and nuclei in the outer galaxy
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +7 more
In the present derivation of the radial distribution of high energy gamma-ray emissivity in the outer Milky Way, the kinematics of H I are used to construct column-density maps in various galactocentric distance ranges that are then used in combination with COS-B spacecraft gamma-ray data to determine emissivities in these distance ranges. The res…
VW HYI : the white dwarf revealed.
Szkody, P.; Mateo, M.
Nonsimultaneous IUE, optical, and near-IR observations of VW Hyi at quiescence are presented. Using these and UV data from other investigations, a broad feature in the ultraviolet is identified with L-alpha absorption. The presence and width of the line imply that (1) the white dwarf in VW Hyi is directly visible in the UV and (2) the effective te…
Observations of Nova MUSCAE 1983 from 1200 A-10 mu-m during its earlydecline stage.
Leitherer, C.; Beuermann, K.; van Paradijs, J. +8 more
Spectroscopic and photometric observations of Nova Mus 1983 were carried out during its early decline phase over a wide spectral range from 1200 A to 10 microns, and the results are presented. Nova Mus 83 was a moderately fast to fast nova whose probable maximum brightness and lifetime were roughly 7 mag and 40 days. A distance of 4.8 + or -1 kpc …
IUE observations of DQ Herculis and its nebula, and the nature of thecold nova shells.
Gondhalekar, P. M.; Lambert, D. L.; Shields, G. A. +4 more
The nebula ejected in the 1934 outburst of the classical nova DQ Her is remarkable for its unprecedentedly low temperature of Te 500 K as measured by Williams et al. (1978). In this paper, IUE observations are combined with Steward optical spectra. It is confirmed that the gas is quite cold. It is further shown that the gas is ionized by the radia…
Multifrequency observations of the BL Lacertae object 0735 +178.
Rieke, G. H.; Pollock, J. T.; Huggins, P. J. +18 more
Four simultaneous spectra covering the radio through the X-ray regimes were made between 1979 October and 1981 March of the variable BL Lac object 0735+178. In each spectrum, the IR-UV synchrotron continuum dominates the total observed power (1047 ergs s-1) and presumably becomes opaque between 1011 and 1013
An unprecedented UV/optical flare in TV Columbae.
Szkody, P.; Mateo, M.
A surprising, 2 mag, short time scale (hr) outburst of TV Col (2A 0526-328) was observed simultaneously at IUE and optical wavelengths in 1982 November. During this 'flare', the IUE emission lines of N v 1240, C IV 1550, and He II 1640, intensified by more than an order of magnitude and developed P Cygni profiles, indicating mass loss. Continuum f…
A study of the diffuse galactic gamma radiation.
Fichtel, C. E.; Kniffen, D. A.
The observed diffuse galactic gamma radiation is compared to that predicted from galactic cosmic ray interactions with galactic matter and photons, assuming that on a broad scale the galactic cosmic rays in the plane are correlated with matter density. Recent considerations of the galactic diffuse matter distribution, particularly the molecular hy…
Evidence for 4.4 hour periodic dips in the X-ray flux from 4U 1755-33.
Parmar, A. N.; White, N. E.; Kahn, S. M. +3 more
The paper reports the discovery by the EXOSAT Observatory of three equally spaced dips in the flux from 4U 1755 - 33 that suggest the binary period of this system to be 4.4 hr. The duration of each dip is of order 30 minutes with considerable variability within each event on time scales between 30 and 600 s. The variations are spectrally independe…
The unique planetary nebula NGC 2818.
Dufour, R. J.
The planetary nebula NGC 2818, or PK 261 + 8 deg 1, is of special interest due to its apparent association with a Population I open cluster (of the same designation). The results of new observations of the nebula are presented, including interference-filter imagery, photoelectric photometry, and ground-based and IUE spectroscopy. Analysis of its c…
Winds in collision. II. an analysis of the X-ray emission from the eruptive symbiotic HM Sge.
Stencel, R. E.; Willson, L. A.; Wallerstein, G. +1 more
X-ray emissions from HM Sge obtained in 1981 from the HEAO-2 satellite are analyzed and compared quantitatively with observations of HM Sge made in 1980 and of HM Sge, V 1016 Cyg, and RR Tel made in 1979. The change in the X-ray emission from HM Sge between 1979 and 1981 is found to be consistent with the X-ray luminosity and/or temperature of the…