BATSE observations of classical novae.

Detection of gamma-ray emission from classical novae, in the range between 30 and 511 keV, would provide a crucial test of the thermonuclear runaway (TNR) model. This emission results from the annihilation of positrons, emitted by some radioactive nuclei ([sup 13]N and [sup 18]F) synthesized during the TNR; it has a short duration and is produced before the optical maximum. Therefore, it can only be analyzed “a posteriori,” once the nova has been discovered optically. The capability to observe all the sky, together with its high sensitivity in the low-energy range, make BATSE an ideal instrument to detect this emission. Data analysis techniques previously applied for BATSE observations of 511 keV transients of short duration have been used. The first results from the systematic search in BATSE background data which is under way are presented, which include nearby novae that have exploded since CGRO launch. Comparison with recent updated theoretical models is made in each case. Although no positive detection has been obtained up to now, upper limits to the emitted flux are presented. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]