The self-sustained turbulence that develops in magnetized accretion disks is suppressed in the weakly ionized, quiescent disks of close binary stars. Because accretion still proceeds during quiescence, another viscosity mechanism operates in these systems. An anticorrelation of the recurrence times of SU UMa dwarf novae with their mass ratio supports spiral waves or shockwaves tidally induced b...

Rapidly accreting massive protostars undergo a phase of deuterium shell burning during pre-main sequence evolution that causes them to swell to tenths of an AU in radius. During this phase, those with close binary companions will overflow their Roche lobes and begin transferring mass. Since massive stars frequently have companions at distances well under 1 AU, this process may affect the early ...

Ice accretion on aircraft wings poses a performance and safety threat as aircraft encounter supercooled droplets suspended in the cloud layer. The details of the ice accretion depend on the atmospheric conditions and the flight parameters. The icing process on the wing consists of a complex interaction of water deposition, surface water transport, and freezing. The aerodynamics affect the water...

Some recent observations of the abundances of s-process, r-process, and α elements in metal-poor stars have led to a new scenario for their formation. According to this scenario, these stars were born in a globular cluster and accreted the s-process enriched gas expelled by cluster stars of higher-mass, thereby modifying their surface abundances. Later on, these polluted stars evaporated from t...

We present new numerical simulations in the thin-disk approximation which characterize the burst mode of protostellar accretion. The burst mode begins upon the formation of a centrifugally balanced disk around a newly formed protostar. It is comprised of prolonged quiescent periods of low accretion rate (typically . 10M⊙ yr ) which are punctuated by intense bursts of accretion (typically & 10M⊙...

A research project is underway at NASA Glenn to produce computer software that can accurately predict ice growth under any meteorological conditions for any aircraft surface. This report will present results from the newest LEWICE, version 3.5. This program differs from previous releases in its ability to model mixed phase and ice crystal conditions such as those encountered inside an engine. I...

A high angular resolution study of the nucleus of the FR I galaxy IC4296 using Chandra ACIS-S and VLBA observations is presented, with the aim of studying the nature of the accretion process. Pointlike and hard X-ray emission is found, well described by a moderately absorbed power law of Γ = 1.48 −0.34; no iron fluorescence line from cold material is detected. The 0.3–10 keV luminosity is 2.4 ×...

Young stellar systems orbiting in the potential of their birth cluster can accrete from the dense molecular interstellar medium during the period between the star’s birth and the dispersal of the cluster’s gas. Over this time, which may span several Myr, the amount of material accreted can rival the amount in the initial protoplanetary disk; the potential importance of this ‘tail-end’ accretion...

We apply an eclipse mapping technique to observations of the eclipsing magnetic cataclysmic variable HU Aqr. The observations were made with the S-Cam2 Superconducting Tunnel Junction detector at the WHT in October 2000, providing high signalto-noise observations with simultaneous spectral and temporal resolution. HU Aqr was in a bright (high accretion) state (V = 14.7) and the stream contribut...