The Nova Outburst: Thermonuclear Runaways on Degenerated Dwarfs
Observational and theoretical studies of the outbursts of classical novae have provided critical insights into a broad range of astrophysical phenomena. Thermonuclear runaways (TNRs) in accreted hydrogen-rich envelopes on the white dwarf (WD) components of close binary systems constitute not only the outburst mechanism for a classical nova explosion, but also the recurrent novae and a fraction of the symbiotic novae explosions. Studies of the general characteristics of these explosions, both in our own galaxy and in neighboring galaxies of varying metallicity, can teach us about binary stellar evolution, while studies of the evolution of nova binary systems can constrain models for the (as yet unidentified) progenitors of Type Ia supernovae. Further, the empirical relation between the peak luminosity of a nova and the rate of decline, which presents a challenge to theoretical models, allows novae to be utilized as standard candles for distance determinations out to the Virgo Cluster. E xtensive studies of novae with IUE and the resulting abundance determinations have revealed the existence of oxygen-neon white dwarfs in some systems. The high levels of enrichment of novae ejecta in elements ranging from carbon to sulfur confirm that there is significant dredge-up of matter from the core of the underlying white dwarf and enable novae to contribute to the chemical enrichment of the interstellar medium. Observations of the epoch of dust formation in the expanding shells of novae allow important constraints to be placed on the dust formation process and confirm that graphite, SiC, and SiO{sub 2} grains are formed by the outburst. It is possible that grains from novae were injected into the pre-solar nebula and can be identified with some of the pre-solar grains or ''stardust'' found in meteorites. Finally, <font face=''symbol''>g</font>-ray observations during the first several years of their outburst, using the next generation of satellite observatories, could confirm the presence of decays from {sup 7}Be and {sup 22}Na.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOD (US)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 760442
- Report Number(s):
- LA-UR-99-3305; TRN: AH200037%%478
- Resource Relation:
- Conference: Cataclysmic Variables: 60th Birthday Symposium in Honour of Brian Warner, No location provided, No date provided; Other Information: PBD: 8 Jul 1999
- Country of Publication:
- United States
- Language:
- English
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