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Neutral hydrogen in Herbig AE stars.
Catala, C.; Czarny, J.; Felenbok, P. +1 more
The authors have observed a sample of Herbig pre-main sequence stars in the near IR O I lines in view of studying the formation mechanisms of these lines and of comparing them to the O I UV resonance triplet at 1304 Å. The observations consist of high resolution (λ/Δλ = 4×104) spectra of the regions 7773 Å and 8446 Å in seven Herbig Ae …
Hot White Dwarfs, OB Subdwarfs, and Dark Clouds
Bessell, M. S.; Wickramasinghe, D. T.; Wegner, Gary +1 more
The authors describe a method of using UBV photographic photometry to survey obscured regions in the Galactic plane for hot white dwarfs and OB subdwarfs. From an initial survey of two regions, the first towards the Coalsack, and the second covering part of the Scorpius-Centaurus cloud, the authors have found at least six white dwarfs, one probabl…
The X-Ray to Infrared Energy Distribution of the Quasar PG 0026+129
Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +4 more
PG 0026+129 was observed with EXOSAT in 1983 and 1984. No variation between the two epochs was detected. The energy distribution from 0.2 to 6 keV is well fitted by a power law of energy index α = 1.06 +/- 0.25 and with Galactic absorption. Quasi-simultaneous spectrophotometry in the UV and optical range, together with near-infrared photometry was…
Discovery of a 9.5-year period in the symbiotic star V1016 Cyg.
Nussbaumer, H.; Schmid, H. M.
Near-infrared observations show that the symbiotic star V1016 Cyg contains a periodicity of 450 days. From ultraviolet observations (IUE) the authors now find a period of 9.5 years. They suggest that V1016 Cyg is a double star system with an orbital period of ≈9.5 years containing a Mira variable. The nature of the source of the hot ionizing radia…
The Loss and Reestablishment of the Wind in 66 Ophiuchi in 1985
Peters, Geraldine J.
Mass loss in the Be star 66 Oph during the first six months of 1985, when the star temporarily lost its wind, is discussed. Both IUE and ground-based CCD observations of Hα have been utilized in this study. Observations of Be stars during such periods of "quiescence" are especially valuable for gaining insight into the mechanisms responsible for t…
A spectral classification of QPO sources
Hasinger, Guenther
The spectral and power-spectral similarities between different modes of the QPO sources Cyg X-2 and Sco X-1 are emphasized. It is shown that low-mass X-ray binaries in general can be found in three different states, forming a Z-shaped spectral correlation diagram. There is a direct relation between the spectral states and three different QPO modes…
Circinus X-1, as viewed by EXOSAT
Tennant, A. F.
In this paper we review the discoveries made with EXOSAT during observations of Cir X-1. Type 1 X-ray bursts were seen in two observations. During the brightest burst, the energy flux was observed to saturate. If we assume this saturation is due to the Eddington limit then it is possible to estimate a distance to the source from the X-ray data alo…
Markarian 52 : a gas-rich starburst galaxy.
Durret, F.; Tarrab, I.
We have observed the "starburst" galaxy Markarian 52(= NGC 4385) both through broad and narrow band imaging, and spectroscopically in the UV and optical ranges. The narrow band Hα+[N II] continuum-free image shows that the ionized gas extends over at least 19" (4.1 kpc). However, our long slit spectroscopic data reveals a much larger extent of the…
IUE Observations of the Dwarf Nova BV Centauri
Hassall, B. J. M.; Wade, Richard A.; Williger, G. +1 more
The IUE observations of the dwarf nova BV Cen in quiescence are summarized. The reprocessed spectra from January 1979 are analyzed to show that the maximum temperature of the white dwarf primary star, based on its brightness at 1375 A, ranges from 42,000 to about 125,000 K depending upon the adopted values of interstellar reddening, the mass of th…
An EXOSAT Observation of CTB 80
Parmar, A. N.; White, N. E.; Angelini, L. +2 more
The results of an EXOSAT observation of the Crab-like supernova remnant CTB 80 are presented. The 0.05-6 keV X-ray spectrum is well fitted by a power law with an energy index of 0.9, similar to that of other Crab-like remnants. This spectral measurement differs from an earlier result from an Einstein observation where a much steeper index was repo…