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The Identification of H 3S + with the Ion of Mass per Charge (m/q) 35 Observed in the Coma of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
A sharp peak in the mass spectrum at 35 amu is observed by the heavy ion analyzer on board the Giotto spacecraft just inside the ionopause. This peak is identified with H3S(+) and it is argued that the dominant source of its likely parent molecule (H2S) is the observed distributed source of circumnuclear dust, rather than the central nucleus. In t…
IUE Observations of WX Ceti in Outburst
Downes, Ronald A.
IUE observations of the peculiar dwarf nova WX Ceti roughly two weeks into a rare outburst, the first since 1963, are obtained. The SWP and LWP observations are very similar to other erupting dwarf novae, both in the line and continuum spectrum. The C IV 1549 A doublet displays blueshifted absorption, indicating the presence of a wind which has a …
Ultraviolet and Infrared Monitoring of FG Sagittae during 1982--1989: Evolutionary Status
Fernandez-Castro, Telmo; Cassatella, Angelo; Eiroa, Carlos +3 more
Ultraviolet IUE spectra and infrared JHKL photometry of FG Sge obtained over the period 1982-1989 indicate that the cooling rate of the star observed until about 1980 seems to have stopped and that an increase of the effective temperature may have occurred, this being a significant change in the evolutionary path traced so far. The current spectra…
IUE Observations of PG 1115+080: The He i Gunn-Peterson Test and a Search for the Lensing Galaxy
Tripp, Todd M.; Green, Richard F.; Bechtold, Jill
We have obtained new IUE observations of PG 1115+080 (z_em_ = 1.722), the "triple quasar," in order to carry out the He I Gunn-Peterson test with greater sensitivity and to search for a Lyman-limit discontinuity which could reveal the redshift of the gravitational lens. We find that n_HE I_(z = 1.722) ~ 7x10^11^ h_100_ cm^-3^ at the 3 σ level. We …
Comparison of picked-up protons and water group ions upstream of comet Halley's bow shock
Coates, A. J.; Neubauer, F. M.; Neugebauer, M.
Data are presented on the properties of picked-up cometary protons and water group (WG) ions observed upstream of the bow shock of comet Halley by the ion mass spectrometer and Johnstone plasma analyzer experiments on the Giotto spacecraft. The number of WG ions exceeded the number of cometary protons at cometocentric distances r<1.3×106
The Evolution of Magnetic Activity on V711 Tauri and Evidence for a Significant Facular Contribution
Guinan, E. F.; Dorren, J. D.
The nature of the long-term evolution of magnetic activity in the RS CVn binary V711 Tauri is investigated using the complete set of available archival IUE SWP low-dispersion spectra of V711 Tau for the period covering August 1978 - December 1984. An analysis of the spectra confirmed the pattern of a long-term smooth variation of chromospheric and…
Giotto magnetic field observations at the outbound quasi-parallel bow shock of comet Halley.
Coates, A. J.; Neubauer, F. M.; Glassmeier, K. H. +4 more
The investigation of the outbound bow shock of comet Halley using Giotto magnetometer data leads to the following results: the shock is characterized by strong magnetic turbulence associated with an increasing background magnetic field and a change in direction by 60° as one goes inward. The thickness of the quasi-parallel shock was 120000 km. The…
The absolute magnitudes of RR Lyrae stars - III. DH Peg.
Jameson, R. F.; Fernley, J. A.; Skillen, I. +1 more
UV optical and IR photometry of the RRc Lyrae star DH Peg is presented. Using this photometry plus previously published data the IR Flux Method of Blackwell & Shallis (1977) is applied to estimate effective temperatures and angular diameters at all phases of the pulsation cycle. The angular diameters are then matched with the integrated radial…
Optical Variability of Extragalactic Objects Used to Tie the HIPPARCOS Reference Frame to an Extragalactic System Using Hubble Space Telescope Observations
Bozyan, Elizabeth P.; Hemenway, Paul D.; Argue, A. Noel
Observations of a set of 89 extragalactic objects (EGOs) will be made with the Hubble Space Telescope Fine Guidance Sensors and Planetary Camera in order to link the HIPPARCOS Instrumental System to an extragalactic coordinate system. Most of the sources chosen for observation contain compact radio sources and stellarlike nuclei; 65% are optical v…
The X-ray orbital lightcurve of TY Pyx : a 3.2-day eclipsing RS CVn system.
Parmar, A. N.; White, N. E.; Culhane, J. L. +1 more
An Exosat observation of one orbital cycle of the eclipsing 3.2-d RS CVn system TY Pyx is reported. This system contains two almost identical GV stars, which is unusual because most RS CVns contain F or G main-sequence star and a K subgiant. The X-ray light curves of the primary and secondary eclipses are different above and below 1 keV. At lower …