View Full Version : Plusar system PSR J1311-3430, and 390 rotations per second?

Mister Earl
2012-Oct-28, 05:05 AM
What shape would a pulsar assume rotating at 390 rotations per second? Talking about this with someone on Fark, and he suggested that the gravity of it was intense enough to keep it perfectly spherical. Now, all the science education I've gotten was basic high school and that was some twenty years ago, but I can't see this being correct at all. I'm thinking its rotation has it looking more like a disc, but not quite a disc. Maybe like a severely flattened and rounded top. Can anyone assist?

2012-Oct-28, 07:33 AM
Pulsars do possess an oblateness - however it is not large enough to make them a disk. Leaving oblateness out of the models for pulsars results in bad prediction of their pulse shapes and variability. Oblateness also affects them as a source of gravitational waves and their evolution. So the answer is somewhere between the two of you - they do deform, but not by a huge amount. There is a limiting mechanism that means that very oblate pulsars lose energy faster and so slow down until the gravitational wave energy loss is small. I think the amount of energy lost depends on the fifth or sixth power of spin rate - so it ramps up fast as they spin faster.