New theoretical results concerning gamma-ray emission from classical
Margarita Hernanz, Jordi José
Jordi Gómez-Gomar, Jordi Isern
New results concerning the synthesis of radioactive elements in classical nova
explosions will be presented, together with their influence on the gamma-ray
emission from these objects and the prospects for the detectability with
present and future instruments. The isotopes involved in gamma-ray emission from
classical novae are 13N, 18F, 7Be, 22Na and 26Al.
Both 13N and 18F are crucial for the short duration annihilation
emission, at 511 keV and below, that is emitted during the first hours after
the outburst, before the nova maximum in visual magnitude. New recent results
concerning the nuclear reaction rates involved in 18F destruction have
been incorporated into our hydrodynamic code, which models the nova explosion
with a detailed follow up of the associated nucleosynthesis. As a result of
the larger rates of 18F destruction through proton captures, this isotope
is produced in smaller quantities (typically by a factor of 10), leading to
smaller fluxes in the 30-511 keV range.
Concerning the medium and long lived isotopes, the implementation of the latest
reaction rates available in the NeNa-MgAl cycles provides an enhanced
22Na production with respect to previous results, leading to a larger
1275 keV flux emitted through its decay. 26Al is practically unchanged.
The implications of our new results for the observability of novae by CGRO and
by the future INTEGRAL instruments will be addressed.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:19.