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Ultraviolet extinction towards far OB associations.

Perinotto, M.; Aiello, S.; Barsella, B. +2 more

Stars in the Aur OB-2 and Sco OB-1 associations, located in the direction of the galactic anticenter and center, respectively, have been observed for interstellar extinction. No effects due to changes of grain composition across such large distances are seen. A star exhibiting a peculiar extinction is found in each association. The properties of t…

Integrated Fluxes for Emission Lines in the Ultraviolet Spectra of Several Planetary Nebulae

Carpenter, K. G.; Czyzak, S. J.

The IUE satellite observatory has been used to obtain absolutely-calibrated emission line fluxes for diagnostic lines of multiply-ionized C, N, O, Si, Ne, and Ar which occur in the ultraviolet spectral region of planetary nebulae. These data, when combined with data from the blue, visual, and near infrared, will provide improved estimates of ionic…

IUE observations of variability and differences in the UV spectra of double quasar 0957+561 a, b.

Wilson, R.; Gondhalekar, P. M.

The continuum flux from 2500-2800 A and the emission flux in the Lyman alpha line were observed to change substantially in component A of the double quasar but not in component B. The equivalent width of the line increased by 50 percent in A but not in B, which was probably not due to instrument effects. It was expected that these changes should r…

The mid-ultraviolet spectrum of EPS Aur.

Kondo, Y.; Castelli, F.; Hoekstra, R.

An LTE synthetic spectrum with Te = 7800 K and log g = 1 has been computed for the 2455-to-3230 A range of Epsilon Aurigae (F0 1a). This has been compared with the spectra observed with 0.2 A resolution with the IUE experiment and with 0.1 A resolution with the BUSS experiment. As a consequence of this comparison, identifications and abundance val…

UV and visible photometry of the brightest Pleiades stars.

Mauron, N.; Golay, M.

This paper describes 7-color photometric observations of the brightest stars in the Pleiades taken over the last 20 years. These data are analyzed in conjunction with UV photometric and spectroscopic observations made with the OAO-II, IUE satellites and a balloon-borne photometer. Accurate determinations of the interstellar extinction are obtained…

Ultraviolet spectra of planetary nebulae. VIII. The C/O abundance ratio in the ring nebula.

Flower, D. R.

The Ring nebula (NGC 6720) has been observed with the International Ultraviolet Explorer satellite. Measurements of line intensities at a position on the ring, offset from the central star, lead to a value of the abundance ratio C/O approximately 1.2, a result which is insensitive to the adopted value of the electron temperature in the nebula.

Ultraviolet radiation from the environment of the Cohen-Schwartz star.

Bohm-Vitense, E.; Bohm, K. H.

The graphite rich Cepheus OB3 association.

Panagia, N.; Perinotto, M.; Barsella, B.

The four optically brightest stars of the Cepheus OB 3 association have been observed with the IUE satellite in the spectral range 1150-3200 A. The extinction suffered by the stars has been investigated. Both the shape of the bump at approximately 2200 A and the behavior of the extinction at longer wavelengths are close to those of the mean inters…

Ultraviolet shell formation at V1016 Cygni.

Feibelman, W. A.

A recent 330 minute high-resolution International Ultraviolet Explorer (IUE) spectrogram of V1016 Cygni shows splitting of the 1550 A component of the C IV resonance doublet, suggesting that a nebular shell is in the process of formation. An expansion velocity of 15 km/s is indicated by the IUE data and corresponds to the low range encountered wit…

Dependence on Reddening of Interstellar Column Densities in the Direction of O-Stars

Mentese, H. H.

We have investigated 14 O-type stars with IUE high resolution SWP spectra in order to improve the relations of element depletions withE(B-V), and to look for other possible relations with two stellar parameters: namely, the rate of mass loss and rotational velocity. The stars were chosen so as to cover several directions in the Galaxy, as well as …