Russell Lecture: Dark Star Formation and Cooling Instability

Optically thin cooling gas at most temperatures above 30K will makecondensations by pressure pushing material into cool dense regions. This workswithout gravity. Cooling condensations will flatten and becomeplanar/similarity solutions. Most star formation may start from coolingcondensations - with gravity only important in the later stages. The idea thatsome of the dark matter could be pristine white dwarfs that condensed slowly onto planetary sized seeds without firing nuclear reactions is found lacking.However, recent observations indicate fifty times more halo white dwarfs thanhave been previously acknowledged; enough to make the halo fraction observed asMACHOS. A cosmological census shows that only 1% of the mass of the Universe is ofknown constitution.Comment: 32 Pages, Latex (uses aastex & natbib), 5 eps figures, submitted to ApJ April 200