Search Publications
Star formation and extinction in extragalactic H II regions.
Kunth, D.; Deharveng, J. M.; Lequeux, J. +1 more
Evolutionary models are presented of far UV luminosity, production of ionizing photons, effective temperature, and ejection of heavy elements for an ionizing star cluster. The way in which interstellar extinction in our Galaxy and inside and outside the H II region affects the UV and optical emission of the complex is discussed. Conclusions are de…
Spectroscopy of the unique degenerate binary star LS I +61 303.
Hutchings, J. B.; Crampton, D.
IUE ultraviolet, and ground-based spectroscopic data are presented and discussed. The primary is a rapidly rotating B0 main-sequence star, with a stable shell. The radial velocities indicate binary motion in a 26.5-day orbit (in agreement with the radio flaring period), with a secondary of mass 1.1-1.5 solar masses. The broad Balmer emission appea…
Interstellar extinction in the Large Magellanic Cloud.
Nandy, K.; Willis, A. J.; Wilson, R. +2 more
Interstellar extinction in the ultraviolet as a function of position in the Large Magellanic Cloud (LMC) is investigated using an enlarged sample of reddened and comparison stars. With the exception of SK-68-108, the extinction curves of the LMC stars do not show significant variation. The mean extinction curve increases towards 2200 A, with some …
Ultraviolet stars in the Orion Nebula and toward HD 147889.
Savage, B. D.; Bohlin, R. C.
The International Ultraviolet Explorer (IUE) was used to obtain low resolution absolute ultraviolet energy distributions for the four Trapezium stars Theta(1) Orionis A, B, C, and D, Theta(2) Orionis A and B, HD 147889, and several unreddened standard stars. The observations for Theta(1) Orionis B reveal a peculiar extended object. The measurement…
3C 273 revisited : confirmation by COS-B of high energy gamma-ray emission.
Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +11 more
The results of a second observation in the Virgo region by the ESA COS-B satellite are presented. The presence of a high- energy (50-800 MeV) gamma-radiation source is confirmed, and its position is consistent with 3C273. The error box at the 90% confidence level containing the quasar is ∼2.5 square degrees, and the probability of a chance coincid…
Ultraviolet interstellar extinction in the Large Magellanic Cloud using observations with the international ultraviolet explorer.
Koornneef, J.; Code, A. D.
Ten early-type supergiants in the Large Magellanic Cloud (LMC) have been observed with the International Ultraviolet Explorer (IUE). The spectra (1150-3200 A) are shown, and their photometric properties are discussed. It is confirmed that the LMC interstellar extinction law for these stars deviates significantly from the average galactic law in th…
Central Object of the 30 Doradus Nebula, a Supermassive Star
Savage, B. D.; Cassinelli, J. P.; Mathis, J. S.
R136 (HD 38268) is the central object of the 30 Doradus Nebula, a giant region of ionized hydrogen in the Large Magellanic Cloud. Observations of R136 at low and high spectral resolution with the International Ultraviolet Explorer reveal a peculiar hot object with a massive stellar wind. An outflow speed of 3500 kilometers per second and a tempera…
The optical and ultraviolet spectrum of the planetary nebula NGC 2440.
Czyzak, S. J.; Shields, G. A.; Keyes, C. D. +1 more
New measurements of the optical and ultraviolet emission-line intensities of the high-excitation planetary nebula NGC 2440 in the wavelength range 1240-8578 A are analyzed with the aid of photoionization models. The observed O III and N II forbidden-line temperatures (13,800 K and 10,000 K, respectively) differ by more than the models predict. Inc…
A model of V1016 CYG based on the ultraviolet spectrum.
Nussbaumer, H.; Schild, H.
The ultraviolet spectrum of the suspected symbiotic star V 1016 Cygni is interpreted in terms of a single star model. Spectra were obtained at low and high resolutions in the range 1100 to 3200 A by the IUE. From analyses of spectral features including the forbidden Ne V lines, He II UV recombination lines and the continuum flux, an interstellar r…
Physical conditions in the nucleus of M 81.
Torres-Peimbert, S.; Peimbert, M.
IUE and visual observations of the emission lines in the nucleus of M8 1 are presented. The permitted lines show broad and narrow features qualitatively similar to those in Seyfert galaxies. The observed luminosity for the broad component is L(Hβ) = 7.4 × 1037 ergs s-1, which is about two orders of magnitude smaller than in t…