Abstract: We consider disk accretion onto a slowly rotating neutron star with a weak magnetic field H < 10^8 G in a wide of luminosities 0.01 < L/Ledd, where Ledd is the Eddington Luminosity. We construct a theory for the deceleration of rotation and the spread of matter over the stellar surface in the shallow-water approximation. The deceleration of Keplerian rotation and energy release take place on the stellar surface in the levitating latitude belt whose meridional extent increases with increasing accretion rate. The combined effect of centrifugal force and radiation pressure gives rise to two latitude rings of enhanced brightness which are symmetric about the equator in the upper and lower hemispheres.

Biog: Rashid Sunyaev was born in Tashkent, Uzbekistan, and educated at the Moscow Institute of Physics and Technology and Moscow University. The head of the High Energy Astrophysics Department of the Russian Academy of Sciences from 1982 to 2002 and chief scientist of the Academy’s Space Research Institute since 1992, he holds several concurrent positions, including editor-in-chief of Astronomy Letters. He currently divides his time between Moscow and Garching, Germany, where he is managing director of the Max Planck Institute for Astrophysics. He worked for several years with his teacher, Yakov B. Zel’dovich, in the Moscow Institute of Applied Mathematics, where the two proposed what is known as the Sunyaev-Zel’dovich effect, an important method for determining absolute distances and hence the Hubble constant from the effect of gas in galaxy clusters on the cosmic microwave background radiation. Sunyaev and N. Shakura developed a model of disk accretion onto black holes, and he has proposed a signature for X-radiation from matter spiraling into a black hole. He has collaborated in important studies of the early universe, including the recombination of hydrogen and the formation of the cosmic microwave background radiation.