Search Publications
Ultraviolet flare on lambda Andromedae.
Dupree, A. K.; Guinan, E. F.; Baliunas, S. L.
On November 5, 6, 1982, a luminous, flarelike brightening of the ultraviolet emissions was observed with IUE from the active RS CVn type star Lambda And during the phase of rotation period corresponding to maximum area coverage of the visible hemisphere by starspots and active regions. Enhancements during the flare in the ultraviolet emission line…
The temperature of C II emission-line formation regions in cool stars.
Carpenter, K. G.; Brown, A.
An investigation has been conducted of the temperature of C II emission-line formation regions in the outer atmospheres of late-type giant and supergiant stars. A distinct dichotomy is seen in the C II lambda 2325/lambda 1335 ratio between coronal and noncoronal stars. It is found that C II emission from noncoronal giant and supergiant stars comes…
IR Geminorum : indications of a massive white dwarf and a heated secondary in this new SU Ursae Majoris cataclysmic variable.
Szkody, P.; Shafter, A. W.; Cowley, A. P.
We report the discovery of a new SU UMa type cataclysmic variable through confirmation of a 102 minute superhump period during a supermaximum. The superhump has a 30% color-independent amplitude with a decrease in the equivalent widths of the Balmer absorption lines. Spectroscopic and photometric studies during quiescence show a 98-101 minute orbi…
An upper limit to the abundance of 9Be in the population II star HD 76932 from a high resolution spectrum with the IUE.
Molaro, P.; Beckman, J.
A high resolution spectrum (Δλ = 0.2 Å) of the Population II star HD 76932 from the archive of the IUE satellite has been analysed in a search for measurable resonance absorption lines due to 9Be. Matching the observations by a synthesized model of the wavelength region around the doublet at 3130 Å gives a conservative upper limit for t…
Cygnus X-2 : neutron star or degenerate dwarf ?
Hammerschlag-Hensberge, G.; McClintock, J. E.; Remillard, R. A. +2 more
Some conflicting models have been proposed for Cyg X-2: a degenerate dwarf model which predicts a distance of 250 + or 50 pc; and a neutron star model which implies a distance of about 8000 pc. Based on a reddening study, it is found that the distance to Cyg X-2 is greater than 1100 pc, which rules strongly against the degenerate dwarf model. This…
Spectral and temporal features in bursts from 2S 1636-536 observed with EXOSAT.
Turner, M. J. L.; Breedon, L. M.
The well-known X-ray burster 2S 1636-536 (Nor X-1) was observed for 7 hr by the ME instrument on EXOSAT. During this time 7 bursts of unusual shape were detected. The bursts have similar profiles. The results suggest that each burst has two components with an initial helium thermonuclear flash triggering a stronger hydrogen flash; the ratio of con…
Non-LTE analysis of subluminous O-stars. VI. Feige 110.
Heber, U.; Kudritzki, R. P.; Hamann, W. -R. +3 more
An analysis of the ultraviolet (1150-2000 A) and the blue 4000-5100 A) spectra of the subdwarf O-star Feige 110 is presented. Effective temperature, gravity and helium abundance of Feige 110 are determined on the basis of NLTE model atmospheres. The effective temperature of Feige 110 is found to be 40,000 K (+5000 or -3000 K). Helium abundances in…
The many faces of Capella : a search for rotational modulations and astudy of systematic velocities of emission lines in the ultraviolet.
Ayres, T. R.
The ultraviolet emission of the spectroscopic binary Capella has been monitored with IUE over the course of half an orbital cycle (2 months). The first objective was to detect changes in the fluxes or shapes of ultraviolet emission lines in response to the evolution of large-scale active regions or their rotation onto and off the visible hemispher…
Ultraviolet observations of starburst and mini-Seyfert galactic nuclei.
Thuan, T. X.
The high excitation emission line galaxies NGC 1667, NGC 5135, and IC 5135 show activity which, while similar to that of Seyfert 2 galaxies, is 1-2 orders of magnitude smaller. The line and continuum emission is in all three cases more extended than would correspond to a point source. In addition to showing such Seyfert-like characteristics as bro…
The double Seyfert nucleus of MKN 266.
Kollatschny, W.; Fricke, K. J.
A long-exposure short-wavelength UV spectrum of the double nucleus galaxy Mkn 266 is discussed along with earlier optical data. The spectra of the two nuclei are well separated and both show evidence of a nonthermal origin. The weaker nucleus towards the SW is of Seyfert type 2 while the NE nucleus has characteristics intermediate between Seyferts…