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The typical interstellar extinction in the Small Magellanic Cloud.
Lequeux, J.; Prevot, L.; Rocca-Volmerange, B. +2 more
The authors give a mean UV extinction curve for the Small Magellanic Cloud which corresponds to the most common case and consequently to the most probable typical extinction law. The curve is almost linear in λ-1 without any evidence of the 2200 Å galactic feature. This is consistent with almost pure silicate interstellar grains and lit…
The nature of magnetic activity in lower main sequence stars.
Vilhu, O.
The chromospheric-coronal emission of lower main sequence single and binary stars is correlated with an activity parameter of the form R = g(B-V)P-1, where P is the rotation period and g(B-V) is a function of the colour resembling the convective turnover time. A more general form of R, including also gravity, is suggested. The functiona…
The atmosphere of sublumious B stars.
Heber, U.; Kudritzki, R. P.; Hunger, K. +1 more
The spectra of eight high galactic latitude B stars, suspected to be subluminous, are analyzed for effective temperature, gravity, and helium to hydrogen ratio. Model atmospheres include (LTE) UV line blanketing (for T/eff/ less than or equal to 30,000 K) and NLTE effects (for T/eff/ greater than 30,000 K). Among the eight confirmed subdwarfs, six…
Spectroscopy of the shell episode of η Car (1981-1983).
Stahl, O.; Wolf, B.; Zanella, R.
High-dispersion spectra of η Car obtained in March 1974, Dec. 1981, and Feb. 1983 have been compared. The spectrum of Dec. 1981 shows conspicuous deviations from the usual spectral appearance of η Car; all lines originating from high ionization and/or excitation levels have dramatically faded. The P Cygni characteristics of the Balmer lines are mo…
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 …
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…
Multispectral analysis in the UV, optical and IR of HDE 245770 = A 0535+26.
Giovannelli, F.; Hensberge, H.; Persi, P. +10 more
The characteristics of the Be/X-ray binary system HDE 245770/A0535+26 are examined from UV, visual, IR and X-ray data. A sequence of observations in the optical preceding an X-ray outburst is interpreted as the ejection of a shell by the Be primary. An evolutionary scenario is presented that produces a system like HDE 245770. An effective temperat…
Physical conditions in the UV line emitting region of supernova 1979cin NGC 4321.
Panagia, N.; Fransson, C.; Reimers, D. +5 more
Ultraviolet observations of SN 1979c are used to derive the physical conditions in the line-forming regions. The emission lines have asymmetric profiles and large expansion velocities and are therefore formed in a narrow shell close to the photosphere having a constant velocity. The most likely mechanism for the excitation of these lines is photoi…
A study of the Herbig Ae-type stars UX ORI and CD -44 3318 based on IUE spectra, and on visual and infrared photometry.
The, P. S.; Tjin A Djie, H. R. E.; Remijn, L.
The spectral classifications of the two Herbig Ae stars UX Ori and CD-44 deg 3318 are reconsidered. The far-UV spectra of the stars are both similar to those of early A-type supergiants; however, the spectral types A2 III and A0-1 III are here derived for the respective stars based on continuum shapes, absorption features, and distance arguments. …
Ultraviolet, optical and infrared observations of the Wolf-Rayet contact-eclipsing binary CQ Cephei.
Bromage, G. E.; Howarth, I. D.; Willis, A. J. +5 more
IUE spectra of CQ Cep covering virtually all binary phases are analyzed, together with new UBVJKL photometry and remeasurements of radial velocities from archived optical spectra. The high resolution UV interstellar line spectrum strongly supports CQ Cep's membership in the Cep OB1 association. Continuum light curves in 15 wavebands, from 0.13 to …