Hopkins Ultraviolet Telescope Observations of Nova Circini 1995 and Nova Aquilae 1995

Bradford W. Greeley and William P. Blair
Department of Physics and Astronomy
The Johns Hopkins University
Charles and 34th Streets
Baltimore, Maryland 21218
E-mail: greeley@pha.jhu.edu

and

Knox S. Long
Space Telescope Science Institute
3700 San Martin Drive
Baltimore, MD 21218

Abstract:

We observed Nova Cir 1995 and Nova Aql 1995 with the Hopkins Ultraviolet Telescope during the Astro-2 space shuttle mission in 1995 March. The spectra provide coverage from 820 Å to 1840 Å with a spectral resolution of about 3 Å, extending the ultraviolet wavelength coverage of novae to the region between Ly and the Lyman limit for the first time. The Nova Cir 1995 observation exhibits many broad carbon, nitrogen, and oxygen emission lines thoughout the HUT wavelength range. We approximate its extinction, and fit absorption by the Lyman and Werner bands of molecular hydrogen to find an H column density of log N(H) = 20.7 cm. We calculate electron temperatures and abundances in the nova shell. The abundances are substantially non-solar, with nitrogen enhanced relative to carbon by a factor of 2, and oxygen deficient by a factor of 9 relative to carbon. The broad asymmetric line profiles in the Nova Aql 1995 spectrum show that this nova has not evolved as quickly as Nova Cir 1995 . The Nova Aql 1995 spectrum is significantly reddened, with little flux detected below Ly . A series of three spectra taken over 10 days shows dramatic changes in the ultraviolet line strengths and profiles as the shell evolves.

Subject headings: novae -- stars: individual (Nova Cir 1995, Nova Aql 1995)





greeley@pha.jhu.edu