Edward F. Brown

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We present a detailed observational and theoretical study of a ∼ 3 hr long X-ray burst (the " super burst ") observed by the Rossi X-ray Timing Explorer (RXTE) from the low mass X-ray binary (LMXB) 4U 1820-30. This is the longest X-ray burst ever observed from this source, and perhaps one of the longest ever observed in great detail from any source. We show(More)
We present an analytic calculation of the thermonuclear depletion of lithium in contracting, fully convective, pre-main sequence stars of mass M ∼ < 0.5M ⊙. Previous numerical work relies on still-uncertain physics (atmospheric opacities and convection, in particular) to calculate the effective temperature as a unique function of stellar mass. We assume(More)
Chronic care facility stay has been shown to be an independent risk factor for venous thromboembolism. Review of the literature, however, reveals a paucity of data addressing the issue of venous thromboembolism in nursing home residents. The purpose of this study was to determine the incidence of venous thromboembolic events among nursing home residents. A(More)
Nuclear reactions occurring at densities ≈ 10 12 g cm −3 in the crust of a transiently accreting neutron star efficiently maintain the core at a temperature ≈ (5–10) × 10 7 K. When accretion halts, the envelope relaxes to a thermal equilibrium set by the flux from the hot core, as if the neutron star were newly born. For the time-averaged accretion rates (∼(More)
We develop and calibrate a realistic model flame for hydrodynamical simulations of deflagrations in white dwarf (Type Ia) supernovae. Our flame model builds on the advection-diffusion-reaction model of Khokhlov and includes electron screening and Coulomb corrections to the equation of state in a self-consistent way. We calibrate this model flame—its(More)
The type-I X-ray bursting low mass X-ray binary KS 1731−260 was recently detected for the first time in quies-cence by Wijnands et al., following a τ outburst ≈13 yr outburst which ended in Feb 2001. We show that the emission area radius for a H atmosphere spectrum (possibly with a hard power-law component that dominates the emission above 3.5 keV) is(More)
We re-analyze the available X-ray spectral data of the type I bursting neutron star transients Aql X−1, Cen X−4, and 4U 1608−522 using realistic hydrogen atmosphere models. Previous spectral fits assumed a blackbody spectrum; because the free-free dominated photospheric opacity decreases with increasing frequency, blackbody spectral fits overestimate the(More)
In quasi-persistent neutron star transients, long outbursts cause the neutron star crust to be heated out of thermal equilibrium with the rest of the star. During quiescence, the crust then cools back down. Such crustal cooling has been observed in two quasi-persistent sources: KS 1731Ϫ260 and MXB 1659Ϫ29. Here we present an additional Chandra observation(More)
We investigate the atmospheres, oceans, and crusts of neutron stars accreting at rates sufficiently high (typically in excess of the local Eddington limit) to stabilize the burning of accreted hydrogen and helium. For hydrogen-rich accretion at global rates in excess of 10 −8 M ⊙ yr −1 (typical of a few neutron stars), we discuss the thermal state of the(More)