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Rotational modulation and flares on RS CVn and BY Draconis stars. XIII. IUE spectroscopy and photometry of II Pegasi during September 1986.
Doyle, J. G.; Rodono, M.; Butler, C. J. +3 more
UV spectroscopy obtained for the RS CVn star II Pegasi in September, 1986, indicates the presence of a rotational modulation effect for the Mg II h and k and O I 1305 A lines; the largest flux is observed when the primary spot concentration is nearly on the opposite hemisphere, and the rotational modulation is noted to be of opposite sense to that…
Fast Winds from the Central Stars of NGC 6543 and NGC 6826
Lamers, H. J. G. L. M.; Perinotto, M.; Cerruti-Sola, M.
The Sobolev exact integration method and high-resolution IUE data are used to examine the properties of the fast winds exhibited by the central stars of the planetary nebulae NGC 6543 and NGC 6826. An attempt is made to evaluate the parameters of the central stars as accurately as possible. The associated mass-loss rates (M-dot) are (4.0 + 10 or -…
One-pole and two-pole X-ray emission in the AM Herculis binary BL Hyi.
Beuermann, K.; Schwope, A. D.
This paper reports the results of extensive X-ray observations of BL Hyi = H0139-68 with the Exosat satellite when the source was in states of low and intermediate brightness. In the low state, X-rays were observed only between orbital phases phi = 0.0 and about 0.4, coincident with the orbital hump of cyclotron emission from the main pole. In the…
The density of cometary protons upstream of comet Halley's bow shock
Schwenn, R.; Balsiger, H.; Neubauer, F. M. +3 more
Cometary protons picked up by the solar wind were detected by the high energy range spectrometer of the Giotto ion mass spectrometer starting at a cometocentric distance of ~12×106 km. On the average, the density of cometary protons varied approximately as the inverse square of the cometocentric distance, reaching a value of 0.11 cm
On the nature of the old nova CP Puppis.
O'Donoghue, D.; Wargau, W.; Warner, B. +1 more
Results are reported from nearly 48 h of high-speed photometry of the ex-nova CP Pup, obtained at Sutherland or Mount Stromlo, and 23 h of spectroscopic coverage from Sutherland, during the period 1985-88. Analysis of the photometry and radial velocities derived from the spectroscopy gives a modulation period of 0.06143 d, free from the alias prob…
Eclipsing Binary Stars as Tests of Gravity Theories: The Apsidal Motion of AS Camelopardalis
Guinan, Edward F.; Boyd, Patricia T.; Maloney, Frank P.
AS Camelopardalis is an 8th-magnitude eclipsing binary that consists of two main-sequence (B8 V and a B9.5 V) components in an eccentric orbit (e = 0.17) with an orbital period of 3.43 days. Like the eccentric eclipsing system DI Herculis, and a few other systems, AS Cam is an important test case for studying relativistic apsidal motion. In these …
The absolute magnitudes of RR Lyrae stars - II. DX Delphini.
Jameson, R. F.; Fernley, J. A.; Lynas-Gray, A. E. +2 more
UV, IR and visual photometry of the short-period RR Lyrae star DX Del is presented and treated by means of the Blackwell and Shallis (1977) IR Flux Method-based formulation of the Baade-Wesselink method. Upon correcting to common reddening, extinction, and radial-velocity conversion factors, as well as applying the Baade-Wesselink analysis of Burk…
A comparison of solar and stellar ultraviolet spectra obtained with SKYLAB and IUE.
Pallavicini, R.; Cheng, C. C.; Cerruti-Sola, M. +1 more
A comparison is presented of 78 Short-Wavelength Primary (SWP) low-resolution IUE spectra of 45 late-type stars and 10 high-resolution Skylab spectra of spatially-resolved solar regions of various degrees of magnetic activity, including quiet areas, plage regions, and one flare. The results show that the different levels of chromospheric and trans…
Coordinated observations of a large impulsive flare on UV Ceti.
Heise, J.; van Genderen, A. M.; Waelkens, C. +16 more
The characteristics of the major flare observed on UV Ceti on Decemmber 1985 at 01:26 UT during an international observing campaign are described. X-ray observations were obtained with Exosat in the 0.06-0.3 keV bands and 1-6 keV bands; optical photometry was obtained in 11 wavelength bands, and spectra were recorded in the wavelength range 3500 t…
Studies of symbiotic stars. I. Location of the UV emitting regions in6 S-type systems monitored by the IUE satellite.
Munari, U.
IUE archive low resolution short wavelength spectra for the 6 binary symbiotic stars EG Andromedae, V1329 Cygni, AG Pegasi, CI Cygni, AX Persi, and SY Muscae are investigated to locate the regions responsible of the UV emission, both lines and continuum. It is demonstrated that, in all these S-type systems, the majority of UV emission lines and co…