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Ultraviolet and Optical Observations of HDE245770 / A:0535+26 System during an X-Ray Flare

Giovannelli, F.; Persi, P.; Bartolini, C. +4 more

We present high and low dispersion UV spectra of HDE 245770, which is the optical counterpart of the recurrent transient X-ray pulsar A 0535+26,during a decay of an X-ray flare. UBV photometric measurements and medium dispersion optical spectra were simultaneously obtained. The energy distribution of the star in the 12 10 micron range is compared …

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.

Presence of MG II emission in R CrB at maximum light.

Kameswara-Rao, N.; Nandy, K.; Bappu, M. K. V.

The high dipersion spectrum of R CrB in the long wavelength obtained near its maximum with the International Ultraviolet Explorer shows the presence of chromospheric Mg II emission. For comparison the spectrum of Gamma Cyg was obtained immediately afterwards. The Mg II emission width of R CrB is found to be the same as that of Gamma Cyg.

UV observations of X-ray sources 2A 0311-227 and 2A 0526-328.

Coe, M. J.; Wickramasinghe, D. T.

IUE satellite observations of the X-ray sources 2A0311-227 and 2A0526-328, which are suspected to be AM Her-type dwarf novae, are reported. Spectra were obtained by the long-wavelength (1900-3200 A) and short-wavelength (110-1900 A) cameras at 10 A resolution over an 8-hr period. The short-wavelength emission lines and continua of 2A0311-227 are f…

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…

On a more extended correlation between COS-B gamma rays and interstellar matter in the Orion region

Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +7 more

Analysis of IUE observations of the galactic corona and the existence of molecular clouds in the halo

Hartquist, T. W.; Tallant, A.

IUE observations of ions in the galactic corona are reanalyzed and Savage and de Boer's (1979) conclusion that the detected hot phase has a temperature proportional to 80,000 K is confirmed. The cold phase must be at a temperature of less than 24,000 K and probably contains substantial amounts of molecular material. Molecules, such as CH(+), OH an…

Line formation in the wind of alf Cyg.

Praderie, F.; Kunasz, P. B.

In the considered investigation, the method reported by Mihalas et al. (1976) is used to search for plausible atmospheric models for Alpha Cyg and to find limits on its mass-loss rate. Assumptions about the wind and underlying photosphere, and the free parameters of the model are described. The best-suited numerical method is discussed and possibl…

Stephanian's star : the energy distribution reveals a nontypical cataclysmic variable.

Szkody, P.

Einstein, IUE, optical multichannel spectrophotometry, and IR observations of Stepanian's star are discussed in terms of other known cataclysmics. While the X-ray flux and IUE emission-line data are similar to that of dwarf novae, the total continuum flux distribution from uv-IR is cooler (peaking near a 10,000 K blackbody) and is unlike either a …

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…