Our weekly Stars and Exoplanets Meeting at Flatiron was all about stellar rotation somehow this week (no we don't plan this!). Adrian Price-Whelan (Flatiron) showed that stellar rotations can get so large in young clusters that stars move off the main sequence and the main sequence can even look double. We learned (or I learned) that a significant fraction of young stars are born spinning very close to break-up. This I immediately thought was obviously wrong and then very quickly decided was obvious: It is likely if the last stages of stellar growth are from accretion. Funny how an astronomer can turn on a dime.
And in that same meeting, Jason Curtis (Columbia) brought us up to date on his work on on stellar rotation and its use as a stellar clock. He showed that the usefulness is great (by comparing clusters of different ages); it looks incredible for at least the first Gyr or so of a stars lifetime. But the usefulness decreases at low masses (cool temperatures). Or maybe not, but the physics looks very different.
In the morning, before the meeting, Megan Bedell (Flatiron) and I built a mechanical model of an asteroseismic mode by literally making a code that produces a damped, driven harmonic oscillator, driven by random delta-function kicks. That was fun! And it seems to work.
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