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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…
Gamma rays from atomic and molecular gas in the large complex of clouds in Orion and Monoceros.
Caraveo, P. A.; Strong, A. W.; Hermsen, W. +4 more
COS-B gamma-ray observations of the large complex of interstellar clouds in Orion and Monoceros are compared with the Columbia CO survey and the Berkeley H I surveys of this region. A good correlation between the gamma-ray emission and the total gas distribution is found. The observed gamma-ray emission can be explained in terms of interactions of…
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…
The radial distribution of galactic gamma rays. II - The distribution of cosmic-ray electrons and nuclei in the outer galaxy
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +7 more
In the present derivation of the radial distribution of high energy gamma-ray emissivity in the outer Milky Way, the kinematics of H I are used to construct column-density maps in various galactocentric distance ranges that are then used in combination with COS-B spacecraft gamma-ray data to determine emissivities in these distance ranges. The res…
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 …
A study of the diffuse galactic gamma radiation.
Fichtel, C. E.; Kniffen, D. A.
The observed diffuse galactic gamma radiation is compared to that predicted from galactic cosmic ray interactions with galactic matter and photons, assuming that on a broad scale the galactic cosmic rays in the plane are correlated with matter density. Recent considerations of the galactic diffuse matter distribution, particularly the molecular hy…
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…