Which indicator traces star formation timescales significantly longer than $10^8$ years, representing the fuel supply?

Answer

$ ext{CO}$ Intensity

The different tracers of star formation sample vastly different timescales. While UV and $ ext{H} ext{ extalpha}$ provide views on the order of $10^7$ years, and Far-Infrared (FIR) emission, tracing heated dust, averages over about $10^8$ years, the molecular gas tracers operate on much longer timescales. $ ext{CO}$ intensity maps the distribution of the molecular hydrogen ($ ext{H}_2$) reservoir, which represents the fuel available for *future* star birth. Since the gas supply lasts much longer than the short lives of the massive stars powering the emission lines, the timescale probed by the $ ext{CO}$ reservoir is much greater than $10^8$ years, effectively showing the potential for star formation over extended cosmic durations.

Which indicator traces star formation timescales significantly longer than $10^8$ years, representing the fuel supply?

Related Questions

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stellar evolutionstar formationastrophysicsnebulaeprotostars