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Coordinated Optical and Ultraviolet Observations of IM Pegasi
Huenemoerder, David P.; Buzasi, Derek L.; Ramsey, Lawrence W.
IUE spectra and optical observations of IM Peg obtained during the summers of 1985 and 1986 are analyzed. The modulations of the UV emission lines and the H-alpha, H-beta, and the CaII IR triplet (IRT) optical lines are examined. It is observed that: the UV emissin-line modulation increases as a function of height, H-alpha variability is related t…
Photospheric absorption lines in the UV spectra of O and B type stars.
Prinja, R. K.
Measurements of the equivalent widths of ultraviolet photo spheric lines of He II λ1640, C III λ1247, N III λλ1748, 1752, O IV λ1339, Si II λ1265, Si III λ1299, Si III λ1417, Si IV λλ1394, 1403 and Fe IV λ1765 in O3 to B5 stars are presented, using high-resolution IUE spectra of 300 supergiant, giant and dwarf stars.
All the ions exhibit a we…H1722+119: A Highly Polarized X-Ray--selected BL Lacertae Object
Schwartz, D. A.; Tuohy, I. R.; Remillard, R. A. +2 more
We report the discovery of a 15th magnitude X-ray-selected BL Lacertae object as part of a program to identify X-ray sources observed by the Scanning Modulation Collimator experiment during the HEAO I all-sky survey. The BL Lac object, H1722+119, is a strong and persistent X-ray source originally discovered by Uhuru and located by the HRI instrume…
A newly discovered carbon-poor planetary nebula : PN 242-37.1
Pena, M.; Torres-Peimbert, S.; Ruiz, M. T. +1 more
An emission line object with galactic coordinates l = 242.17 deg and b = - 37.11 deg corresponding to a previously unreported very high-excitation planetary nebula is described. The spectrophotometric data obtained in October 1988 is detailed, as well as the UV observations from a satellite in November 1988. Reddening and physical conditions are o…
Rotational modulation and flares on RS Canum Venaticorum and BY Draconis-type stars. XV. Observations of Proxima Centauri and solar calibration data.
Foing, B.; Rodono, M.; Butler, C. J. +2 more
Results are reported from simultaneous Exosat and IUE observations of flaring in Proxima Cen on March 2, 1985. The data are presented in extensive tables and sample spectra and discussed in detail. The peak emission of the soft-X-ray flare is found to be about 3 x 10 to the 27th erg/sec, with energy about 3 x 10 to the 30th erg and an associated i…
Flaring and quiescent X-rays from Castor.
Schmitt, J. H. M. M.; Tagliaferri, G.; Pallavicini, R. +2 more
Using data obtained with the Low Energy (LE) and Medium Energy instruments aboard Exosat, the first detection of both flaring and quiescent X-ray emission from the A-type visual binary Castor (alpha Gem) is reported. In the LE, Castor was clearly resolved from the nearby star YY Gem, which was also observed to flare some hours after Castor. After …
Erratum: Velocity space diffusion of pickup ions from the water group at comet Halley'' [J. Geophys. Res. 94, 9983 (1988)]
Coates, A. J.; Glassmeier, K. -H.; Wilken, B. +2 more
Large dust particles along the Giotto trajectory
Keller, H. U.; Curdt, W.
Images of Comet Halley taken by the Halley Multicolour Camera (HMC) onboard ESA's Giotto spacecraft provide highly accurate information on the viewing direction. As a part of the spacecraft dynamical system, HMC was very sensitive to attitude variations that occurred during the final approach phase. HMC identified several discrete events that were…
Plasma flow inside Comet P/Halley
Johnstone, A.; Amata, E.; Formisano, V. +2 more
The plasma flow parameters (bulk velocity, number density, temperature) have been computed from the Giotto JPA data for the solar wind protons and for the water group cometary implanted ions. The decrease of the plasma bulk speed due to mass loading is followed from the bow shock at 1.16 x 10 to the 6th km from the nucleus down to well inside the …
EXOSAT observations of a long X-ray burst from XB 1905+000.
Ilovaisky, S. A.; Chevalier, C.
During a 17-hour continuous Exosat observation of the faint X-ray source XB 1905 + 000 a single burst was detected which shows a long decay following a radius expansion-contraction phase near maximum bolometric flux. The best spectral fits for the persistent emission are found when a 10-percent contribution from a cool blackbody component is added…