Fermi establishes classical novae as a distinct class of gamma-ray sources

Abstract

Gamma-ray novas may be garden variety When astronomers detected gamma rays from the nova V407 Cyg, an explosive mass transfer from a red giant onto a white dwarf, they found it surprising enough. They blamed the rays on strong stellar winds enabling particle acceleration. Now, the Fermi-LAT Collaboration has observed gamma rays from three more novas, all lacking the strong winds. Although the three sources vary slightly in nature, none is particularly unusual. If all novas emit gamma rays, then astronomers would expect to see the same number of novas that they did in fact see within a 5-kpc distance over 5 years. Science , this issue p. 554