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Titolo:
THERMONUCLEAR RUNAWAYS IN NOVA OUTBURSTS .2. EFFECT OF STRONG, INSTANTANEOUS, LOCAL FLUCTUATIONS
Autore:
SHANKAR A; ARNETT D;
Indirizzi:
INDIANA UNIV,DEPT ASTRON,SWAIN W 319 BLOOMINGTON IN 47405 UNIV ARIZONA,STEWARD OBSERV TUCSON AZ 85724 UNIV ARIZONA,DEPT PHYS TUCSON AZ 85721
Titolo Testata:
The Astrophysical journal
fascicolo: 1, volume: 433, anno: 1994,
parte:, 1
pagine: 216 - 228
SICI:
0004-637X(1994)433:1<216:TRINO.>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
ACCRETION DISKS; CLASSICAL NOVAE; BOUNDARY-LAYER; MODELS; CARBON; SUPERNOVAE; OXYGEN; DWARF; TIME;
Keywords:
HYDRODYNAMICS; NOVAE, CATACLYSMIC VARIABLES; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES; STARS, INTERIORS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
A. Shankar e D. Arnett, "THERMONUCLEAR RUNAWAYS IN NOVA OUTBURSTS .2. EFFECT OF STRONG, INSTANTANEOUS, LOCAL FLUCTUATIONS", The Astrophysical journal, 433(1), 1994, pp. 216-228

Abstract

In an attempt to understand the manner in which nova outbursts are initiated on the surface of a white dwarf, we investigate the effects fluctuations have on the evolution of a thermonuclear runaway. Fluctuations in temperature, density, or the composition of material in the burning shell may arise due to the chaotic flow field generated by convection when it occurs, or by the accretion process itself. With the aid of two-dimensional reactive flow calculations, we consider cases wherea strong fluctuation in temperature arises during the early, quiescent accretion phase or during the later, more dynamic, explosion phase. In all cases we find that an instantaneous, local temperature fluctuation causes the affected material to become Rayleigh-Taylor unstable. The rapid rise and subsequent expansion of matter immediately cools thehot blob. which prevents the lateral propagation of burning. This suggests that local temperature fluctuations do not play a significant role in directly initiating the runaway, especially during the early stages. However, they may provide an efficient mechanism of mixing core material into the envelope (thereby pre-enriching the fuel for subsequent episodes of explosive hydrogen burning) and of mixing substantial amounts of the radioactive nucleus N-13 into the surface layers, makingnovae potential gamma-ray sources. This suggests that it is the global, not the local, evolution of the core-envelope interface to high temperatures which dominates the development of the runaway. We also present a possible new scenario for the initiation of nova outbursts basedon our results.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/11/20 alle ore 14:38:56