Synthesis of radioactive nuclei and gamma-line radiation from novae
Alexander D. Kudryashov
A possible range of radioactive nuclei abundances in CO and ONeMg
nova ejecta was found on the basis of kinetic computations of the
thermonuclear burning in the one-zone hydrogen-rich envelope.
The total amount of radioactive N, O and F isotopes in the model
envelope is determined by the amount of dwarf CO matter admixed during
the accretion and/or outburst.
The fraction of synthesised 18F is 0.1-1% by mass.
We calculated light curves of annihilation line from the
short-lived NOF isotopes for various envelope parameters
(expansion velocity, mixing degree) and
expansion kinematics (free expansion against wind-like outflow).
Light curve as a rule consists of two major peaks.
Their intensity is sensitive to the degree of mixing of
radioactive isotopes in the envelope.
The presence of only one per cent of unmixed matter in the outer
layer leads to the strong suppression of the first luminosity peak
related to radioactive N and O isotopes.
However, the second luminosity peak determined by 18F decays
survives if the fraction of the outer unmixed layer is less than 10%.
We propose to use 18F annihilation line flux observations
by CGRO and INTEGRAL and independent estimate of the total amount
of synthesised 18F from the 18O mass in the envelope to
assess the mixing degree of radiactive nuclei.
Calculations of the amount of synthesised 22Na and 26Al
are compared with upper limits from gamma-ray observations.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 12:44.