Search Publications
Anomalous extinction in the planetary nebula Abell 30.
Greenstein, J. L.
The stellar continuous energy distribution from 8000 to 1250 A in Abell 30 is quite peculiar. The observed flux can be understood if a hot central star (approximately 200,000 K) is immersed in an absorbing dust cloud which has anomalous absorption with its peak near 2470 A. The dust nebula is a strong infrared source, maintained by conversion of t…
Ionized species observed in the spectrum of the nearby white dwarf G 191-B2B.
Kondo, Y.; Bruhweiler, F. C.
High-resolution spectra of the nearby (48 pc) white dwarf G191-B2B, obtained with the International Ultraviolet Explorer, reveal sharp resonance lines of N V, C IV, and Si IV. The origin of these features is most likely linked to the white dwarf, possibly being formed in an expanding halo around the star. Interstellar lines of C II, N I, Mg II, Si…
IUE observations of two elliptical galaxies : NGC 3379 and NGC 4472.
Capaccioli, M.; Oke, J. B.; Bertola, F.
The International Ultraviolet Explorer observations of the nuclei of the elliptical galaxies NGC 3379 and NGC 4472 show that the flux drops rapidly with decreasing wavelength until about 2300 A, below which the flux increases rapidly. The hot UV component of the radiation can be approximately represented by a blackbody at 30,000 K. The spectra of …
On the relationship between coronae and mass loss in late-type stars.
Raymond, J. C.; Dupree, A. K.; Hartmann, L.
High-dispersion spectra taken with the IUE are used to examine the temperature stratification of the wind of the hybrid atmosphere star Alpha TrA (K4 II). C IV emission is shown to have a line width of 150-200 km/s, with Si III and C III exhibiting 100 km/s widths. It is suggested that the line widths reflect wind expansion, with C IV formed in an…
Concerning the Wolf-rayet and other luminous early-type stars.
Underhill, A. B.
Effective temperatures, radii, and luminosities were determined from S2/68, ANS, UBV, and uvby photometry for four B0/B1 supergiants, four O4 stars, and four WN7/WN8 stars as well as for four test stars having spectral types between B1.5 V and 09 V and five stars with known angular diameters and effective temperatures. The effective temperatures o…
On the origin and distribution of C IV and SI IV ions in the neighboring interstellar medium.
York, D. G.; Cowie, L. L.; Taylor, W.
IUE spectrometer observational data are reported on the C IV, Si IV, and N V absorption lines in 46 distant stars at FWHM resolution of 30 km/sec. A simple analytic theory is given for these contributions, including the effects of ionization by a soft X-ray background. While for some of the most distant field stars a photoionized contribution may …
Water production models for comet Bradfield /1979 X/
Feldman, P. D.; A'Hearn, M. F.; Weaver, H. A. +1 more
Whipple (1950, 1951) has proposed that water might be the dominant volatile constituent of the cometary nucleus. The considered investigation is concerned with the clues which observations of the cometary coma provide regarding the parents of the dominant observed coma species. In the early part of 1980, comet Bradfield (1979 X) was observed with …
Ultraviolet emission of the VELA supernova remnant and the Cygnus Loop
Raymond, J. C.; Dupree, A. K.; Black, J. H. +1 more
Ultraviolet emission spectra of several filaments in the Vela supernova remnant and the Cygnus Loop are compared with theoretical models of radiative shocks. Shock velocities range from 85 to 130 km/s. Little or no grain depletion is apparent. Several of the observed filaments deviate from the steady-flow models in the sense that much of the photo…
Ultraviolet and coordinated; ground-based observations of A And.
Altamore, A.; Baratta, G. B.; Friedjung, M. +4 more
High- and low-resolution UV spectrograms of the symbiotic star Z Andromedae were made during 1978-79 with the International Ultraviolet Explorer (IUE) and coordinated with ground-based observations. The spectrograms extend from 1200 to 3341 A and show a rich emission line spectrum with a wide range of ionization energy, from O I, Mg I and II and F…
IUE observations of pre-main-sequence stars. I. MG II and CA II resonance line fluxes for T Tau stars.
Calvet, N.; Giampapa, M. S.; Imhoff, C. L. +1 more
IUE satellite and Lick 3 m reflector image tube scanner measurements of the Mg II and Ca II resonance lines in a sample of T Tauri stars are the basis of a discussion of the Mg II h and k line emission and the Ca II H and K line emission, within the context of stellar chromospheres. Corroborative evidence is presented for the chromospheric origin …