Search Publications
The unusual carbon star HD 59643 : alternative models.
Querci, M.; Johnson, H. R.; Eaton, J. A. +2 more
The authors discuss a binary model for the star in which the secondary spectrum is formed in an accretion disk. If this hot, ultraviolet-emitting disk radiates like a 20,000K black-body, it must be ≤0.03 R_sun; across at minimum emission. Large widths of C IV multiplet UV1 on high-resolution spectra indicate its formation in the inner parts of a d…
The vanishing shell phase of PLEIONE in the far UV in 1988.
Doazan, V.; Thomas, R. N.; Bourdonneau, B.
Far UV observations made with the IUE in 1988, when the shell spectrum of Pleione was vanishing in the visible region, are compared with previous IUE observations made when the shell was strong (1979) and when it began to weaken (1985). Between the epochs of strong shell and vanishing shell: (1) the apparent continuum level increases in all the ob…
Are tides responsible for enhanced MG II emission in late-type binaries ?
Glebocki, R.; Stawikowski, A.
Mg II h and k fluxes are measured for a homogeneous sample of 30 G III and K III binaries. The spectra have been obtained from the IUE archive and calibrated in absolute units (erg cm-2s-1). Contrary to the generally accepted view that the rate of rotation is responsible for the enhanced chromospheric activity, the Mg II h an…
Analysis of C II resonance lines in some main sequence early-type stars.
Cugier, H.; Hardorp, J.
An analysis of C II resonance lines at 1335 Å in eight main-sequence stars of spectral types A0 to B3 is performed using IUE archival data released for general use. In order to interpret the observed spectra, both LTE and non-LTE line profiles were computed. In stars with low rotational velocities (Vega, π Cet, τ Her and ι Her) the authors obtaine…
A sudy of the continuum flux and the line structure in the IUE spectrum of beta Lyrae.
Sahade, J.; Hack, M.; Engin, S. +5 more
A study of the available archival IUE images of Beta Lyrae has led to the following results: (1) for lambda in the range of 1250 - 1500 A, the eclipse depth at second conjunction is slightly larger than the eclipse depth at primary conjunction; they are equal at about 1670 A; (2) the profiles of the resonance lines of SiIV (and the same seems to b…
Electron densities in late-type stars.
Dufton, P. L.; Lennon, D. J.; Byrne, P. B. +2 more
Recently published atomic calculations for the C II UV 0.01 intersystem multiplet at 2325 Å are combined with dearchived IUE data on a number of late-type giants and supergiants to derive the electron densities in these stars' upper chromospheres/lower transition regions. The results represent a substantial change from previously derived values. T…
Mass loss and C IV ionization in the stellar wind of OB stars.
Blomme, R.; van Rensbergen, W.
A sample of 19 stars is presented for which both IR and UV observations are available. From the IR, the mass loss rate M can be determined, but it depends on the velocity law in the stellar wind, which is parameterized by the parameter beta(IR). This dependence on beta turns out to be similar for all stars. From the UV, one finds the mass loss rat…
Position of comet P/Halley at the Giotto encounter
Wilhelm, K.; Keller, H. U.; Curdt, W. +2 more
Images of the Halley Multicolor Camera (HMC) were analyzed to evaluate the fly-by geometry of the Giotto spacecraft past Comet Halley. The position of the comet at closest approach was determined with respect to the spacecraft. Based on the orbit information of Giotto the absolute position of the cometary nucleus could be obtained with very high p…
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 …
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…