Accretion Rates in X–ray Bursting Sources

We present estimates for the accretion rates in 13 X–ray bursting sources which exhibit photospheric expansion, basing on theoretical models of stationary, radiatively driven winds from neutron stars. The relatively high values obtained, Ṁacc∼> 10 M⊙/yr, are in accordance with theoretical limits for unstable helium burning, and, at the same time, almost never exceed the “dynamical” limit for stationary accretion, ∼ 10ṀEdd. The only exceptions are 1820-30, already known to be a very peculiar object, and 1608-522; there are indications, however, that in both sources, accretion could be non–stationary. Subject headings: accretion, accretion disks – stars: binaries – stars: individual – stars: neutron – X–rays: bursts Accepted for publication in the Astrophysical Journal § The Royal Astronomical Society Sir Norman Lockyer Fellow