The heating of nova ejecta by radioactive decays of the β-unstable nuclei

Shlomi Pistinner, Giora Shaviv, Sumner Starrfield

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Recent nucleosynthesis and hydrodynamic calculations of the consequences of accretion onto massive ONeMg white dwarf stars show that under certain circumstances significant amounts of the β-unstable nuclei can be produced and ejected by the resulting explosion. We use these calculations as a guide in order to obtain the conditions under which the heating of the ejected material by the nonthermal electrons and positrons produced by the decays of the β-unstable nuclei is sufficient to overcome the cooling from adiabatic expansion and lead to the production of X-ray-emitting coronal gas. These conditions are as follows: 1. A mass fraction for 22Na of the order of 10-3 or greater. 2. An expansion velocity in the range ∼ 102-103 km s-1. 3. A photospheric radius of ∼ 1014 cm. 4. If the density distribution in the atmosphere satisfies a power law, then the exponent must be less than 3 for heating to overcome adiabatic cooling. Both the simulations of the outburst and the model atmosphere fits to the observed energy distributions, however, imply that the exponent is ≥ 3 during the early phases of the outburst. Nevertheless, for a value of the exponent of 2, we predict the time when hot coronal gas can form during the expansion phases of the envelope.

Original languageEnglish (US)
Pages (from-to)794-801
Number of pages8
JournalAstrophysical Journal
Volume437
Issue number2
StatePublished - Dec 20 1994

Fingerprint

radioactive decay
ejecta
outburst
exponents
heating
cooling
nuclei
expansion
atmosphere
gas
white dwarf stars
explosion
atmospheres
power law
hydrodynamics
accretion
nuclear fusion
gases
electron
density distribution

Keywords

  • Novae, cataclysmic variables
  • Nuclear reactions, nucleosynthesis, abundances
  • Stars: coronae
  • White dwarfs

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

The heating of nova ejecta by radioactive decays of the β-unstable nuclei. / Pistinner, Shlomi; Shaviv, Giora; Starrfield, Sumner.

In: Astrophysical Journal, Vol. 437, No. 2, 20.12.1994, p. 794-801.

Research output: Contribution to journalArticle

Pistinner, Shlomi ; Shaviv, Giora ; Starrfield, Sumner. / The heating of nova ejecta by radioactive decays of the β-unstable nuclei. In: Astrophysical Journal. 1994 ; Vol. 437, No. 2. pp. 794-801.
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