Search Publications
Ultraviolet spectral morphology of the O stars. II. The main sequence.
Walborn, N. R.; Panek, R. J.
A survey of the 1200-1900 A region in 49 spectra of types O3-B1 V, based upon IUE high-resolution data, is presented. Standard sequences of prominent spectral features are illustrated, and UV classification criteria are introduced. For the majority of the stars, there is an excellent correlation between the behavior of the UV features, both stella…
Ultraviolet spectroscopy of the dwarf nova U Geminorum.
Holm, A. V.; Panek, R. J.
Spectrophotometry at 6 A resolution is presented for the dwarf nova U Gem over the range 1150-3200 A, with simultaneous visual broad-band photometry, from observations with the International Ultraviolet Explorer. The observations were made at 1, 5, 11, 26, 71, and 108 days after the start of an outburst. Near the outburst maximum the spectra show …
Photospheric soft X-ray emission from hot DA white dwarfs.
Raymond, J. C.; Wesemael, F.; Kahn, S. M. +3 more
Soft X-radiation (≡150 eV) from four hot DA white dwarfs (EG 187, Gr 288, Gr 289, and LB 1663) has been detected with the imaging proportional counter of the Einstein Observatory. The observed pulse-height spectra are very soft and suggest that the emission arises from the hot photosphere with implied effective temperatures in the range 30,000 - 6…
Effective temperatures and luminosities of very hot O type subdwarfs.
Drilling, J. S.; Schonberner, D.
Twelve very hot O-type subdwarfs were observed with the IUE-satellite in the low dispersion mode. Temperatures were derived from the slopes of the UV continua and distances were estimated from the color excesses. Most of them are hotter than 60,000 K, i.e., they are the hottest known subdwarfs. From their spectral appearance and location in a H.R.…
International Ultraviolet Explorer observations of stars in 30 Doradus : extinction and stellar continua.
Savage, B. D.; Fitzpatrick, E. L.
A study of ultraviolet interstellar extinction in and near the core of the 30 Doradus nebula is presented. The pair method is used to determine the shape of the ultraviolet extinction curve, and reddened stars from within 80 pc of the core and unreddened stars from a variety of locations in the Large Magellanic Cloud (LMC) are considered. All star…
The variation of galactic interstellar extinction in the ultraviolet.
Bohlin, R. C.; Witt, A. N.; Stecher, T. P.
The interstellar extinction in the UV (3.25 µm-1 ≤ λ-1 ≤ 8.0 µm-1) has been determined from IUE spectra for 29 reddened early-type stars by use of the pair method. The star sample was selected on the basis of highly deviant ratios of the strength of the 4430 Å diffuse interstellar absorption feature to …
The problem of the barium stars.
Bohm-Vitense, E.; Proffitt, C.; Nemec, J.
The authors report on ultraviolet observations of barium stars and other cool stars with peculiar element abundances. Those observations attempted to find hot white dwarf companions. Among six real barium stars studied, only ζ Cap was found to have a white dwarf companion. Among seven mild, or marginal, barium stars studied, at least three were fo…
Evidence for a high-temperature accretion region in Algol-type binarysystems.
Peters, G. J.; Polidan, R. S.
The recent discovery of strong absorption lines of N V, C IV, and Si IV in the UV spectra of Algol primaries, whose photospheric temperatures are much too cool to form such ions, has suggested the presence of a high-temperature component in the circumstellar matter in these systems. The authors have employed timed, high-resolution IUE observations…
IUE observations of DQ Herculis and its nebula, and the nature of thecold nova shells.
Gondhalekar, P. M.; Lambert, D. L.; Shields, G. A. +4 more
The nebula ejected in the 1934 outburst of the classical nova DQ Her is remarkable for its unprecedentedly low temperature of Te 500 K as measured by Williams et al. (1978). In this paper, IUE observations are combined with Steward optical spectra. It is confirmed that the gas is quite cold. It is further shown that the gas is ionized by the radia…
Multifrequency observations of the BL Lacertae object 0735 +178.
Rieke, G. H.; Pollock, J. T.; Huggins, P. J. +18 more
Four simultaneous spectra covering the radio through the X-ray regimes were made between 1979 October and 1981 March of the variable BL Lac object 0735+178. In each spectrum, the IR-UV synchrotron continuum dominates the total observed power (1047 ergs s-1) and presumably becomes opaque between 1011 and 1013