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The variable shell star HR 5999.
Hack, M.; The, P. S.; Tjin A Djie, H. R. E. +1 more
High and low resolution IUE spectra of the Herbig Ae-type star HR 5999 show strong emission lines of H, O I, C II, C IV, Mg II and possibly C III, N I and O V, and numerous shell absorption lines, mainly of Fe II, Cr II, Mn II and Ni II. The presence of strong emission lines due to hot gas suggests that Hr 5999 has a chromosphere and a corona, pro…
Analysis of the IUE and optical spectra of the peculiar Be star HD 87643.
Pottasch, S. R.; de Freitas Pacheco, J. A.; Gilra, D. P.
IUE observations of the peculiar Be star HD 87643 are presented. The broad absorptions seen at 2400 A, 2600 A, and 2750 A are interpreted as being produced by Fe II transitions from the ground-state and the low lying metastable states. The optical lines of Fe II seen in emission are most probably excited by continuum fluorescence. This interpretat…
Variability and mass loss in the extreme supergiant zet01 Sco.
Bianchi, L.; Cassatella, A.; Heck, A. +1 more
It is found that the photometric variability can be characterized by a unique relationship between the half-period and the amplitude in the V band. This kind of variability differs from that characterizing the best known pulsating stars. One explanation, advanced tentatively, is that p and g modes are simultaneously excited. What is considered a m…
MGII H and K line observations of del SCT variables.
Fracassini, M.; Pasinetti, L. E.
IUE observations of seven Delta Scuti variables and a comparison star are reported with a comparison of the Mg II h and k lines to those of previously observed normal stars. Evident chromospheric emission is observed in three Delta Scuti variables: tau Cyg, beta Cas and rho Pup. Possible emissions are suggested for omega-1 Eri (F2III), iota Cyg, t…
Further VBLUW photometry of the S DOR type variables S DOR and HDE 269006 in the LMC and a discussion on their temperatures.
van Genderen, A. M.
New VBLUW photometry of the S Dor type variables S Dor and HDE 269006 in the LMC made in 1979 and 1981 are discussed. S Dor has reached the lowest brightness in 1981 of the last 8 yr, but it is still far from the minimum. HDE 269006 was at minimum brightness. Temperatures are estimated for the central star and the envelope by fitting black body en…
The UV spectrum of the old nova HR Del at differentorbital phases.
Friedjung, M.; Puget, P.; Andrillat, Y.
Observations of the old nova HR Del with IUE are used to obtain a dereddened continuum energy distribution, which is close to that of a classical accretion disk of Lynden-Bell. A very high accretion rate of 0.000001 solar mass/yr is derived from this distribution. The variations of line and continuum fluxes with orbital phase are examined. They ca…
Discovery of CA II absorption at 1840 angstrom in IUE spectra of two helium-rich white dwarfs.
Koester, D.; Weidemann, V.; Vauclair, G. +2 more
The spectrum of the white dwarf star L 745-46 A, which is classified as DF because of the presence of Ca II H and K lines in the visible region, is found to contain the strong Ca II 1840 A absorption line in the IUE short wavelength region. The same line is more weakly in evidence in the short wavelength IUE spectrum of L 791-40, which is a DC sta…
Interpretation of line profiles of the symbiotic star V1016 Cyg.
Nussbaumer, H.; Kindl, C.; Marxer, N.
Profiles of the strongest UV emission lines of the symbiotic star V 1016 Cyg have been extracted. These profiles are compatible with the assumption that V 1016 Cyg is very young planetary nebula. The line profiles show two components. The narrow main component originates in the nebular shell. It is concluded that the wide feet are due to emission …
New evidence of strong UV radiation in TT Ari.
Vogt, N.; Drechsel, H.; Rahe, J. +1 more
Three SWP spectra and one LWR spectrum of the cataclysmic variable TT Ari were obtained with the IUE satellite during three different brightness phases, including the brightness minimum of November 1980. The absolute continuum intensity distribution in the UV and optical regions is examined in relation to several steady-state optically thick accre…
On the spin down episodes of Vel X-1.
Molteni, D.; Robba, N. R.; Rapisarda, M. +1 more
The ESA COS-B satellite observed the X-ray source Vela X-1 in July/August 1976 and in October/November 1979 in the energy range 2-12 keV. Different pulse periods, 282.819 and 282.782 s, were determined for the two observations respectively. These values confirm the presence of spin up and spin down processes in this source.