Search Publications
Evolution of chromospheres and coronae in solar mass stars : a far-ultraviolet and soft X-ray comparison of Arcturus (K2III) and alf CEN A (G2V).
Linsky, J. L.; Simon, T.; Ayres, T. R.
IUE far-UV and Einstein Observatory soft X-ray observations for the red giant Arcturus and the nearby yellow dwarf Alpha-Centauri A, which are archetypes of solar mass stars in different stages of evolution, are compared. Evidence is found for neither coronal soft X-ray emission from the red giant, at surface flux levels of only 0.0006 that detect…
The low state of AM HER : observations from 0.12 to 10 microns.
Raymond, J. C.; Szkody, P.; Capps, R. W.
Observations of AM Her during a low state over a wavelength range from 0.12 to 10 microns are reported. These include IUE ultraviolet spectra, light curves at U, B, V, R, J, H, K, and magnitudes at L, M, and N. The UV observations reveal a nearly Rayleigh-Jeans continuum spectral distribution and broad Lyman-alpha absorption from a hot (effective …
Physical conditions in the accretion disk of V603 Aql.
Lambert, D. L.; Shields, G. A.; Ferland, G. J. +2 more
Ultraviolet and optical spectra of the old nova V603 Aql are discussed. The UV-optical continuum is dominated by emission from the accretion disk. Emission lines from ions of H, He, C, N, and O are identified. These lines are probably formed in a circumstellar shell with radius comparable to the binary separation, density ten billion per cu cm, an…
The violent interstellar medium associated with the Carina Nebula. I.The line of sight toward HD 93205.
Paul, J. A.; Pettini, M.; Laurent, C.
Four high velocity and two low velocity components have been identified by the analysis of interstellar absorption lines in high resolution spectra of HD 93205. The chemical composition and physical conditions of the different regions are discussed in light of UV, optical and radio observations, and the two main high velocity components are found …
Ultraviolet observations of four symbiotic stars.
Feibelman, W. A.; Kafatos, M.; Michalitsianos, A. G. +1 more
Observations were obtained with the International Ultraviolet Explorer (IUE) of four symbiotic stars. The UV spectra of YY Her, SY Mus, CL Sco, and BX Mon are characterized by varying degrees of thermal excitation. These low resolution spectra have been analyzed in terms of line-blanketed model atmospheres of early A, B, and F type stars in order …
Ultraviolet spectroscopy of the nova-like variable V3885 Sgr.
Sion, E. M.; Guinan, E. F.
Low-dispersion long and short wavelength IUE spectra of the nova-like system V3885 Sgr were obtained on 1979 August 24 UT. The UV spectrum exhibits strong, high-temperature absorption lines of C III, C IV, He II, N IV, N V, and Si IV which all have relatively large negative velocities of 600-1000 km/s at their line centers. The C IV (1550 A) featu…
The peculiar extinction of Herschel 36.
Wolf, J.; Donn, B.; Pipher, J. L. +2 more
The extinction of Herschel 36 has been measured and been found to be peculiar in the same sense as that observed in Orion. Following the treatment of Mathis and Wallenhorst (1981), this can be explained by the presence of silicate and graphite grains that are larger than those normally found in the interstellar medium. Correcting the stellar flux …
IUE observations of the peculiar star RX Pup.
Feibelman, W. A.; Kafatos, M.; Michalitsianos, A. G.
The first set of high-dispersion UV observations of RX Pup are presented. Anomalous line profile structure observed in a number of high-excitation emission lines is discussed in context with a model that includes streams and complex mass motions in the system. Anomalies in high-excitation lines suggest dynamic activity in circumstellar material th…
Ultraviolet spectrophotometry of 2A 1822-37.1 : a bulge on the accretion disk.
Mason, K. O.; Cordova, F. A.
It is suggested that the 5.57-hour modulation of the X-ray source 2A 1822-371 is caused by the combined effects of (1) an occultation of the emitting region by a companion star, and (2) a bulge on the accretion disk surrounding the X-ray source. It is speculated that the changing aspect of the X-ray-heated inner face of the bulge with orbital phas…
Ultraviolet spectroscopy of planetary nebulae in the Magellanci Clouds.
Gull, T. R.; Stecher, T. P.; Maran, S. P. +1 more
Ultraviolet spectra of the high excitation planetary nebulas LMC P40, SMC N2, and SMC N5 are presented in an investigation of their chemical composition in an effort to make reliable estimates of the carbon abundance in extragalactic planetary nebulas. The carbon abundance is found to be almost 40 times more abundant in the SMC planetaries than in…