Search Publications
Ultraviolet spectrum variability of UX UMa.
Holm, A. V.; Panek, R. J.; Schiffer, F. H., III
IUE spectra show UX Ursae Majoris to be a spectacular ultraviolet line spectrum variable on time scales of months. Time-resolved spectra around the orbit show that the continuum is strongly eclipsed, whereas the line emission is not. Features in the light curve which are identified with a hot spot are not prominent in the far-UV. The UV line emiss…
Spectral analysis of the OB subdwarf HD 149382.
Kudritzki, R. P.; Scholz, M.; Simon, K. P. +1 more
The ultraviolet and blue spectrum of the OB subdwarf HD 149 382 is analyzed in an investigation of the star's evolutionary status. An effective temperature of 35,000 + or - 2000 K is derived from fitting the observed continuum, hydrogen lines and helium lines to fluxes of unblanketed non-LTE models. LTE analyses of heavy-element lines yield defici…
The interpretation of the spectra of two magnetic degenerates
Oke, J. B.; Greenstein, J. L.
Ultraviolet and optical fluxes are measured for two magnetic degenerates, Feige 7 (Gr 267) and Grw + 70 deg 8247 (EG 129), from 10,000 to 1150 A. A method is developed for fitting blackbodies and models to this broad range of fluxes. From models, the best effective temperatures average 20% below the blackbody temperatures. Feige 7, a mixed H + He …
The ionization structure of the ring nebula. II. Ultraviolet observations.
Barker, T.
Good agreement is found for O and N abundances, and the importance of charge-transfer reactions to the ionization of Ne is confirmed, in UV observations of emission line intensities for four positions in the Ring Nebula that have been previously studied optically. It is noted that the C(2+) abundance inferred from the optical 4267 A recombination …
Ultraviolet absorption by interstellar gas near the LMC star HD 36402in the interstellar bubble N51D.
de Boer, K. S.; Nash, A. G.
Four interstellar absorption components associated with the immediate surroundings of the star are found in UV, high-dispersion IUE spectra of the LMC star HD 36402 in the N51D nebulosity. The 305 km/sec absorption is found to originate in low-density, 10,000 K gas, and the density and velocity structures agree with that derived from visual emissi…
Angular diameters, effective temperatures, radii and luminosities of 03, 04 and 05 stars.
Underhill, A. B.
UV and visible photometry is used to determine the effective temperatures, angular diameters, linear radii and luminosities of 24 O3, O4, and O5 stars. No correlation is found between effective temperatures, which ranged from 24,800 K to 63,000 K, and spectral type or luminosity class for the early O stars. Since conditions in the outer atmosphere…
High-energy γ-ray light curve of PSR0531 + 21
Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +8 more
The Crab pulsar (PSR0531 + 21) was one of the earliest identified sources of high-energy γ radiation1-6. As such it was selected as the first object of detailed study by ESA's γ-ray astronomy satellite COS B, launched in August 1975. The experiment and mission have been described elsewhere7. In the first 6 yr of operation COS…
The gaseous galactic halo as infrared from the line spectra of the galaxies Markarian 509 and Fairall 9.
York, D. G.; Cowie, L. L.; Blades, J. C. +3 more
Narrow interstellar absorption lines of S II 1259.52, Si II 1260.42, and Fe II 1608.46 due to gas in the disk and the halo of the Galaxy have been detected in the spectrum of the Seyfert galaxy Mrk 509 with the International Ultraviolet Explorer. This gas is also seen at higher resolution in the Ca II and Na I absorption lines in two components at…
Chromospheric MG II emission in A5 to K4 main sequence stars from high resolution IUE spectra.
Blanco, C.; Catalano, S.; Marilli, E. +1 more
Observations of the emission cores of the Mg II resonance doublet for 11 main sequence stars in the spectral type range A5-K5 obtained with the IUE satellite at 0.2 A resolution are discussed. Calibrated observed fluxes are used to evaluate the Mg II chromospheric losses as they correlate with effective temperature convection and rotation and othe…
The ultraviolet continuous and emission line spectra of the Herbig-Haro objects HH 2 and HH 1.
Nemec, J. M.; Boehm-Vitense, E.; Cardelli, J. A. +1 more
Recent studies of the continuous spectrum of Herbig-Haro (HH) objects at optical and near-infrared wavelengths and the observation of continuous radiation in the ultraviolet have shown an unexpectedly steep increase of the flux toward shorter wavelengths. The present investigation provides the results of ultraviolet observations of HH 2. The obtai…