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A superoutburst of the dwarf nova EK Trianguli Australis.
Hassall, B. J. M.
Simultaneous UV and optical spectrophotometry were obtained during several stages of a superoutburst of EK TrA. The observed spectra are compared with steady disc models, built both of blackbodies or Kurucz stellar atmospheres and with optically thin contributions. Atmosphere models predict much lower mass transfer rates than blackbody models. Ass…
Long-term stability of the Io high-temperature plasma torus
Skinner, T. E.; Durrance, S. T.; Feldman, P. D. +3 more
The IUE satellite was used to monitor the UV line emission of S+, S++ and S+++ ions in the high-temperature portion of the Io plasma torus. Thirteen observations obtained over a 5 yr period from 1979 March to 1984 March show that the plasma parameters of the high-temperature portion of the torus have surprisingly s…
X-Ray Emission from Cataclysmic Variables
Mason, K. O.
EXOSAT results on cataclysmic variables are reviewed. The long continuous X-ray observations afforded by this observatory, coupled with the sensitivity of its instruments to medium energy and very low energy X-rays, have enabled the rotational and orbital X-ray light curves of these stars to be measured in unprecedented detail. Examples are given …
Simultaneous X-ray and optical observations of the X-ray dip source X1755-338.
Parmar, A. N.; White, N. E.; Mason, K. O.
Simultaneous X-ray and optical observations have been made of the 'dipping' X-ray source X1755-338 which has a dip recurrence period of 4.4 hr. A sinusoidal modulation of amplitude 0.4 mag is found in the V-band light of the 18 mag optical counterpart of the X-ray source. The period of the optical modulation is consistent with the X-ray dip recurr…
Observational studies of the symbiotic stars. III. High-dispersion IUE and H alpha observations of EG Andromedae.
Stencel, R. E.; Anderson, C. M.; Slovak, M. H. +1 more
High-dispersion IUE and optical spectra are presented for the symbiotic star EG Andromedae (HD 4174). Remarkable emission-line strength and profile variations are confirmed for the S IV, O IV, C IV, and He II ultraviolet lines as well as H-alpha. Accurate cross-correlation absorption-line velocities determined from Ti I, Ca I, and Fe I features co…
Effects of nuclear uncertainties and chemical evolution on the standard big bang nucleosynthesis
Gry, C.; Audouze, J.; Delbourgo-Salvador, P. +1 more
It is shown that consistent predictions of baryonic densities can be made only for some specific galactic-evolution models involving D and He-3: either the infall of already processed material such that D/Dp = 1/15 (where Dp is the primordial abundance of D and D is the present value) or the effect of stellar mass loss releasing D free He-3 rich m…
The ionization structure of planetary nebulae. V. NGC 3242.
Barker, T.
Spectrophotometric observations of emission line intensities over the spectral range 1400 A to 9600 A were made in five positions in the planetary nebula NGC 3242. In two of the positions, both the weakness of the 1548 A, 1550 A C IV resonance lines and the steepness of the Balmer decrement suggest the possibility of internal dust in the nebula. T…
COS-B gamma-ray sources and interstellar gas in the first galactic quadrant. Caravane collaboration for the COS-B satellite.
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +8 more
The consequences are considered for the high-energy gamma-ray sources of the recently established correlation between the intensity above 300 MeV, and tracers of atomic and molecular gas, in the first quadrant of the Galaxy. Using a likelihood method on the complete set of COS-B data, it is shown that there are point-like gamma-ray sources which d…
Atmospheric parameters of the variable DB white dwarf GD 358.
Koester, D.; Weidemann, V.; Vauclair, G. +3 more
This paper presents new observations of GD 358, the prototype of the class of variable white dwarfs with helium-dominated atmospheres (DB). These data, together with previous observations, are analyzed using new model atmosphere calculations. The results are Teff = 24000±1000K, log g = 8.0±0.3. This temperature is within the range predi…
Condensation of dust around the WC7 star HD 192641 (WR 137).
Telesco, C. M.; van der Hucht, K. A.; Longmore, A. J. +4 more
The WC7+ absorption class Wolf-Rayet star WR 137 (=HD 192641) is shown to have brightened significantly in the infrared since 1978, most rapidly between 1983 and mid-1984. This is ascribed to an increase in the mass loss rate and the condensation of dust grains in the stellar wind. At maximum, the dust mass was about 10-8 Msun