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Ultraviolet Observations of Interstellar Absorption Lines toward SN 1987A
Jenkins, Edward B.; Savage, Blair D.; Joseph, Charles L. +1 more
An average of all high-resolution UV spectra of SN 1987A recorded by IUE a few days after the explosion reveals numerous interstellar absorption lines between 1200 and 3100 A. Features produced in the neutral medium of our Galaxy and the LMC (e.g., those arising from O I, C I, C II, Mg I, Mg II, Fe II, Mn II, Si II, Ni II, etc.), together with lin…
He 2-104: A Link Between Symbiotic Stars and Planetary Nebulae
Shaw, Richard A.; Lutz, Julie H.; Kaler, James B. +2 more
Ultraviolet, optical and infrared observations of He 2-104 are presented, and estimates for some of the physical properties of the nebular shell are made. It is argued that He 2-104 is in transition between the D-type symbiotic star and bipolar planetary nebula phases and, as such, represents a link between subclasses of these two types of objects…
The Discovery of 2.93 Hour Periodic Intensity Dips from X1323-619
Parmar, A. N.; van Paradijs, J.; van der Klis, M. +1 more
A 30 hr duration Exosat observation of the low-mass X-ray binary X1323-619 is reported. The 1-8 keV light curve obtained with the medium-energy (ME) instrument shows irregular intensity dips that recur every 2.93 hr as well as type 1 X-ray bursts. The intensity declines to about 50 percent of its unaffected value during the 50-minute duration dips…
Absorption dips and the properties of the accretion stream in polars.
Motch, C.; King, A. R.; Watson, M. G. +1 more
Simultaneous X-ray, optical and infrared observations of the absorption dips in the polar system EF Eri are presented. These observations are used to determine the properties of the dips and develop a simple model for the dips in which they are caused by absorption in the accretion stream as it crosses the line-of-sight to the X-ray/optical emissi…
Multi-Wavelength Observations of Stellar Flares
Byrne, P. B.
We present observational data on stellar flares from a range of wavelength regimes, many of which were obtained simultaneously. Physical parameters of these flares are derived and discussed in the frame-work of the general solar flare model. It is found that flares on dMe stars are solar-like, except in mean energy. The parameters of flares on RS …
Observations of a shock and a recombination layer at the contact surface of comet Halley
Schwenn, R.; Altwegg, K.; Balsiger, H. +6 more
Observations in the vicinity of the contact surface (ionopause) of comet Halley obtained by the Giotto ion mass spectrometer (IMS) are reported. Two specific events in this region were observed on the inbound pass. Two seconds before the contact surface was encountered, a burst of energized ions (about 20 eV, much greater than thermal energies) wa…
X-Ray Spectroscopy of the Ultrasoft Transient 4U 1543-47
White, N. E.; van der Woerd, H.; Kahn, S. M.
The X-ray transient 4U 1543 - 47 was observed in August 1983 by the Exosat observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). A broad (FWHM about 2.7 keV) line at 5.9 keV is detected in the GSPC, which is interpreted as a …
Soft X-ray observations of the VELA pulsar PSR 0833-45.
Oegelman, H.; Zimmermann, H. -U.
X-ray maps produced from Exosat observations of the Vela pulsar in the 0.03-2.4 keV range confirm the components discussed by Harnden et al. (1985). Restricting the central source to a neutron star with an 8-15 km radium emitting blackbody-like radiation suggests a surface temperature in the 600,000 to 1,000,000 K. It is found that the observed bl…
Flux-flux relation : MG II H and K versus X-rays in dwarf M and K stars.
Doyle, J. G.; Mathioudakis, M.
Surface X-ray and Mg II h and k fluxes are presented for a group of dMe, dKe, dM, and dK stars. No correlation is apparent between the fluxes for the group of stars as a whole, although a good correlation is present for a subgroup, i.e., the dMe/dKe's. The Mg II and X-ray luminosities for these active stars define an upper boundary, which is depen…
Chromospheric Structure of Cool Carbon Stars
Johnson, Hollis R.; Luttermoser, Donald G.; Avrett, Eugene H. +1 more
A semiempirical chromospheric model is proposed for TX Psc which is a prototype for the N-type carbon stars. Observational data imply that the chromospheric temperature rise must begin at a low density, that the temperature gradient in the lower chromosphere must be steep, that partial redistribution must be employed in the Mg II calculation, and …