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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…
Comet Bowell 1980b
Feldman, P. D.; A'Hearn, M. F.; Schleicher, D. G. +2 more
The authors have carried out optical filter photometry and optical and ultraviolet spectrophotometry of Comet Bowell over the period November 1980 - June 1982. They have observed emission by OH at heliocentric distances to nearly 5 AU preperihelion with the OH emission implying a production rate which decreased, but with outbursts, as the comet ap…
The nature of symbiotic stars.
Kenyon, S. J.; Webbink, R. F.
Synthetic spectra from 0.1 to 3.5 µm are computed for various binary models of symbiotic stars. These models consist of three components: (1) a late-type giant or bright giant, (2) a hot companion, and (3) a surrounding nebula which is photoionized by the hot component. Hot stellar sources, disk accretion onto white dwarf stars, and disk acc…
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…
Detailed observations of NGC 4151 with the IUE - III. Variability of the strong emission lines from 1978 February to 1980 May.
Tanzi, E. G.; Tarenghi, M.; Perola, G. C. +8 more
Observations of the variability of the three strong ultraviolet emission lines in the Seyfert galaxy NGC 4151 (C IV, C III] and Mg II) are used to study the structure of the broad line region and the nuclear energy source of this active galaxy. Data on the line profile variations further permit the kinematic mapping of the broad line region throug…
IUE observations of high-redshift quasars.
Schmidt, M.; Green, R. F.; Heckman, T. M. +5 more
The authors have measured the continuum energy distributions of nine high-redshift quasars (1.0 ≤ z ≤ 2.2) with the IUE and the Palomar 5 m multichannel spectrophotometer. Generally, the spectral energy distributions steepen at a rest wavelength of about 1200 Å, from a power law, in the optical, of spectral index α ≈ -0.5, to a spectral index of -…
Selective excitation of Fe II in the laboratory and late-type stellaratmospheres.
Jordan, C.; Johansson, S.
Low resolution spectra of cool giants and supergiants observed with the International Ultraviolet Explorer (IUE) satellite contain emission features for which it has been difficult to establish unambiguous identifications. High resolution spectra of RR Tel and Beta Gru (M 3 II) show lines which can be definitely attributed to Fe II. The presence o…
X-ray observations of a large sample of cataclysmic variable stars using the Einstein Observatory
Mason, K. O.; Cordova, F. A.
This paper presents the results of an X-ray survey of 31 known or suspected cataclysmic variables. Eighteen of these close binary systems are detected with inferred luminosities in the 0.1 - 4.0 keV band of between 1030 and 1032erg s-1. The majority have relatively hard X-ray spectra (kT > 2 keV) irrespective of…
The dust around R Coronae Borealis type stars.
Holm, A. V.; Wu, C. -C.; Hecht, J. H. +1 more
Measurements taken by the International Ultraviolet Explorer spacecraft of the stars RY Sgr and R CrB have been analyzed using Mie theory. The extinction data, which show a 2400-2500 A peak, are consistent with a distribution of 5-60 nm glassy or amorphous carbon particles obscuring the stellar flux. The data are also fairly consistent with a clou…