11 ms·
Not an expert. How slow would it have to spin for it to be appreciably “slow” after it speeds up as a neutron star, and how many celestial bodies are spinning
by Waterluvian 2y ago
Not an expert. How slow would it have to spin for it to be appreciably “slow” after it speeds up as a neutron star, and how many celestial bodies are spinning that slowly in general?
So, why do bodies accrete in a non-uniform way as to inherit a significant spin far more often than not? Is that bias found in the matter being accreted? Similar to why things seem to rotate the same way: one direction eventually prevails?
- hatthew 2y agoSuper basic estimate (I'm not an astronomer, this could be wrong): The core of a star has a radius of 100000 km, and after collapse the radius becomes 10 km. Angular momentum is proportional to fr^2, where f is the rotation frequency. Since the radius decreases by 4 orders of magnitude, to keep the same angular momentum the frequency must increase by 8 orders of magnitude. This means that if the new rotation frequency is 1/hour, the original must have been around 10000 years. Statistically some stars like that probably exist somewhere, but it's unlikely that one of the few thousand neutron stars we know of started that way.
- Waterluvian 2y agoPlus the survivorship bias of those very few. We don’t observe the ones that aren’t spinning much.