Search Publications
Images in the rocket ultraviolet : the starburst in the nucleus of M 83.
Bohlin, R. C.; Stecher, T. P.; Cornett, R. H. +2 more
Ultraviolet images of the SAB(s)c I-II galaxy M83 (NGC 5236) obtained with a rocketborne telescope in broad bandpasses centered at 1540 A and 2360 A show a bright resolved nuclear source which accounts for approximately 20 percent of the flux of the galaxy in both bandpasses. Low-resolution International Ultraviolet Explorer spectra of this source…
Two hot, low-field magnetic DA white dwarfs.
Green, R. F.; Liebert, J.; Stockman, H. S. +2 more
The authors report the discovery of two hot DA white dwarf stars from the Palomar Green Survey, one of which is proved to be, and the other likely to be, a star with surface magnetic field in excess of 106 gauss. PG 1658+441 has an energy distribution fitted by a 30,000 K pure hydrogen atmospheric model. Circular spectropolarimetry reve…
Chromospheric and coronal emissions from the giants in the Hyades.
Dupree, A. K.; Hartmann, L.; Baliunas, S. L.
The visible Ca II K and International Ultraviolet Explorer spectra from the four K0 III stars (theta-1, gamma, delta, and epsilon Tau) in the Hyades, along with a field giant of similar spectral type, beta Gem, have been measured. Among the Hyades giants, the range of the high-temperature emissions can be a factor of 6 or more for C IV and an orde…
Chromospheric emission of W Ursae Majoris-type stars and its relationto the structure of their common envelopes.
Eaton, J. A.
Short-wavelength IUE spectra of 14 W UMa binary systems were analyzed. All but the A2 V system GK Cep and possibly the A8 system AG Vir show chromospheric and transition-region emission lines. This property extends to at least as early as A8-9. The luminosity in transition-region emission lines is roughly proportional to bolometric luminosity. The…
Outer atmospheres of cool stars. XIII. Capella at critical phases.
Linsky, J. L.; Ayres, T. R.; Schiffer, F. H., III
The results are presented of a program of high-dispersion spectroscopy of Capella at critical orbital phases utilizing the International Ultraviolet Explorer. The considered program had the objective to establish as carefully as possible the relative ultraviolet emission levels of the Capella primary and secondary in order to obtain an understandi…
Observationally determined Fe II oscillator strenghts.
Shull, J. M.; Seab, C. G.; van Steenberg, M.
Absorption oscillator strengths for 21 Fe II resonance lines, have been determined using a curve-of-growth analysis of interstellar data from the Copernicus and International Ultraviolet Explorer (IUE) satellites. In addition to slight changes in strengths of the far-UV lines, new f-values are reported for wavelength 1608.45, a prominent line in i…
Multifrequency observations of the flaring quasar 1156+295.
Spinrad, H.; Impey, C.; Pollock, J. T. +19 more
A report is presented on the optically violent variable quasar 1156+295, known also as 4C 29.45 and Ton 599. A large outburst of this quasar was discovered in April 1981 in the course of a program to obtain simultaneous multifrequency spectra of variable quasars. Ultraviolet observations taken with the International Ultraviolet Explorer satellite …
The nature of R 136a, the superluminous central object of the 30 Doradus nebula.
Savage, B. D.; Ebbets, D. C.; Fitzpatrick, E. L. +1 more
The authors present an analysis of all their IUE ultraviolet data obtained so far for R136a, the central object of the 30 Doradus nebula. They present new average UV spectra with much higher signal-to-noise ratios than those discussed in an earlier paper. New information about the problems due to the presence of nearby stars in the crowded field i…
IUE observations of the high velocity symbiotic star AG Draconis during active phase.
Altamore, A.; Baratta, G. B.; Friedjung, M. +5 more
New high and low resolution IUE spectra of AG Dra, obtained when the star was still in its active phase, are analyzed and interpreted. The spectra are characterized by strong permitted and weak intercombination emission lines belonging to a wide ionization range, from O I, Mg II, to He II, O V, S V, superimposed on an intense continuum. Several st…
Ultraviolet Spectroscopy and the Composition of Cometary Ice
Feldman, P. D.
Our current knowledge of the composition of the cometary nucleus is largely inferred from observations of the gas and dust comae that are produced by sublimation of cometary ice when a comet is near the sun. During the past decade, far-ultraviolet spectroscopy from above the terrestrial atmosphere has shed new light on the physics and chemistry of…