Search Publications
UV spectroscopy of planetary nebulae.
Perinotto, M.; Benvenuti, P.
The planetary nebulae IC 2149 and NGC 2440, 3242, and 6826 are investigated with spectra obtained using the IUE satellite in the spectral range 1150-3200 A at a resolution of 7 A. The physical conditions in the nebulae are derived, as are the abundances of C, N, O, and Ne. It is noted that carbon is essentially solar while nitrogen appears slightl…
The ultraviolet spectrum of the X-ray source 2A 0526-33.
Bonnet-Bidaud, J. M.; Mouchet, M.; Ilovaisky, S. A. +1 more
Low resolution spectra of the X-ray source 2A0526-33 have been obtained with IUE. The X-ray source 2A0526-33 is confirmed as a cataclysmic variable from both its line and continuum ultraviolet spectra. Observed emission lines are similar to those found in other systems, such as EX Hya (Bath et al., 1980), AM Her or SS Cyg at quiescence (Fabbiano e…
Theoretical and observed UV energy distributions of 7 globular clusters
Nesci, R.
A grid of synthetic UV spectra is computed and the effects of the various parameters are shown. A comparison with the integrated spectra of 7 globular clusters is made with satisfactory results, suggesting that constraints on the HB morphology and the chemical composition may be achieved on the basis of the UV fluxes alone. A spread in the observe…
An ultraviolet study of NGC 7662.
Perinotto, M.; Benvenuti, P.
Spectroscopic observations obtained by the IUE of the planetary nebula NGC 7662 are discussed. Physical conditions in the central regions of the nebula are determined from the intensities of the O III and Ne IV lines, resulting in an electron temperature profile which increases with the ionization potential of the ions, in agreement with predictio…
Phase-dependent optical and ultraviolet observations of the old nova V603 AQL (1918).
Drechsel, H.; Krautter, J.; Rahe, J. +1 more
Continuous photometric and ultraviolet spectroscopic observations of the old nova V 603 Aql (1918) were simultaneously carried out with the IUE satellite. Periodic visible light variations with an amplitude of about 0.3 m were discovered, and an orbital period of 3h18.3m was derived. The UV spectroscopy revealed strong variations of the emission l…
Ultraviolet observations of LMC X-4 and SMC X-1.
Hammerschlag-Hensberge, G.; van der Klis, M.; Willis, A. J. +4 more
Low-resolution IUE spectra of the massive X-ray binaries LMC X-4 and SMC X-1 have been obtained at both short and long wavelengths. The continua are consistent with expected early-type model atmosphere fluxes showing small amounts of reddening and exhibit the characteristic double-wave light curves seen at visible wavelengths.
Ultraviolet observations of 27 CMa, pi AQR and 48 Lib.
Ringuelet, A. E.; Rovira, M.; Fontenla, J. M.
An analysis of 27 CMa, Pi Aqr, and 48 Lib, Be stars and V/R variables is discussed to determine the physical conditions and the gaseous structure surrounding the stars. On the basis of two different types of absorption lines the narrow and deep, and the broad and shallow profiles, the gaseous structure is divided into two regions: (1) a geometrica…
IUE MG II doublet observations in F and G main sequence stars.
Ponz, J. D.; Garcia-Alegre, M. C.; Vazquez, M.
Mg II resonance lines at 2800 A were studied in the spectra of F and G main sequence stars, observed with the IUE satellite in high resolution mode. Correlation with other chromospheric indicators were investigated and a search was conducted for the best candidates to continue further studies of differential rotation. An attempt has been made to s…
Transition region structure in F dwarfs.
Saxner, M.
Strong transition region line emission detected in the IUE spectra of two F dwarfs is discussed. The corresponding surface fluxes are found to be comparable to those of active binaries, such as RS CVn-systems. Line flux ratios formed from the multiplets Si IV 1394 A + 1403 A, C IV 1549 A, and N V 1240 A are used in deriving the structure of the tr…
Evidence for autoionization and dielectronic recombination of SI II in the atmospheres of B-type stars.
Underhill, A. B.
Observations are reported demonstrating that both of the 3s3p3d 2F0 levels of Si II autoionize in the atmospheres of B-type stars. A justification is given for concluding that the 2F05/2 level which lies below the laboratory position for the 3s2(1S) limit of Si II, autoio…