AAS 196th Meeting, June 2000
Session 17. Stellar Remnants
Oral, Monday, June 5, 2000, 2:00-3:30pm, Highland A/K

## [17.03] Helium Detonations on Neutron Stars

M. Zingale, F. X. Timmes, B. Fryxell, D. Q. Lamb, K. Olson, A. C. Calder, L. J. Dursi, P. Ricker, R. Rosner, J. W. Truran (University of Chicago), P. MacNeice (Goddard Space Flight Center), H. Tufo (University of Chicago)

We present the results of a numerical study of helium detonations on the surfaces of neutron stars. We analyze the evolution of a detonation as it breaks through the envelope of the neutron star and propagates across its surface. A series of surface waves propagate across the pool of hot ash with a speed of 1.3 \times 109 \ cm \ s-1, matching the speed expected from shallow water wave theory. The entire envelope bounces in the gravitational potential well of the neutron star with a period of 50 \mu s. The photosphere reaches a height of 15 km above the surface of the neutron star. The sensitivity of the results to the spatial resolution and assumed initial conditions are analyzed, and the relevance of this model to Type I X-ray bursts is discussed.

This work is supported by the Department of Energy under Grant No. B341495 to the Center for Astrophysical Thermonuclear Flashes at the University of Chicago.