WHY is so little gas observed within globular clusters? A typical globular cluster contains ∼103 post-turn off stars, each of which will lose ∼0.2M⊙ before its asymptotic giant branch phase of evolution, and ∼0.1M⊙ during this phase1, and so should accumu-late 102∼103M⊙ of gas in the 108-year interval between passages of the globular cluster through the galactic disk. (At each disk passage, gas ram pressure will remove the accumulated material2,3.) But observational searches show that there is scant intracluster gas; in many clusters, there is less than 1M⊙ of gas, orders of magnitude less than theoretical predictions3. The recent discovery4,5 of multiple millisecond pulsars in globular clusters may resolve this long-standing problem: the relativistic wind from these pulsars is enough to drive gas from stellar mass loss out of the globular cluster.
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