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Spectroscopy of a Balmer-dominated filament in the Cygnus Loop with the Hopkins Ultraviolet Telescope
- Source :
- Astrophysical Journal, Part 1. 400(1)
- Publication Year :
- 1992
- Publisher :
- United States: NASA Center for Aerospace Information (CASI), 1992.
-
Abstract
- A fair UV spectrum of a nonradiative filament in the Cygnus Loop covering the wavelength range 830-1860 A at 3.5-A resolution was obtained using the Hopkins Ultraviolet Telescope (HUT) on the Astro-1 space shuttle mission. Nonradiative shock models which include a more sophisticated treatment of Lyman line transfer are calculated. It is found that the HUT spectrum can be explained in terms of a shock with velocity 175-185 km/s propagating into a low-density medium. This shock velocity can be reconciled with the 135-km/s width of the broad component of H-alpha in this filament if equilibration of the postshock electron and ion temperatures proceeds much more rapidly than Coulomb equilibration time scales. The time required for a 180-km/s shock to develop a partial recombination zone is short, about 200 yr if n is approximately equal to 2/cu cm. This suggests that the shock is decelerating as it encounters denser material. The current analysis patently favors rapid equilibration of electrons and ions behind the shock.
- Subjects :
- Astrophysics
Subjects
Details
- Language :
- English
- ISSN :
- 0004637X
- Volume :
- 400
- Issue :
- 1
- Database :
- NASA Technical Reports
- Journal :
- Astrophysical Journal, Part 1
- Notes :
- NAS5-27000, , NAGW-528, , NAG5-87
- Publication Type :
- Report
- Accession number :
- edsnas.19930032124
- Document Type :
- Report
- Full Text :
- https://doi.org/10.1086/171988