Here's a news item I found yesterday on Space.com on the detection of a strange form of superconducting matter called a superfluid in Cassiopea A (Cas A) . Cas A is a neutron star and the youngest known supernova remnant in the Milky Way and a distance of about 11, 000 light-yrs. The drop in temperatures is consistent with theory that predicts that a neutron star should undergo a sharp "cool-down" as it transforms to the superfluid state.Neutron stars are dense objects, and models have been developed to predict how matter behaves at these high densities, including the possibility that super-fluids will form. In this report, NASA researchers found a huge temperature drop in Cas A. The drop in temperatures is consistent with theory that predicts that a neutron star should undergo a sharp "cool-down" as it transforms to the superfluid state. NASA suggests that Cas A can serve as a test case for studying the way ultra-dense matter behaves at the atomic level. The research provides the first direct evidence for superfluid neutrons and protons in the core of a neutron star.
Thanks for posting this. This actually happens to be my own particular subject area in astrophysics. It has been generally accepted for the last half century, even before neutron stars were confirmed as existing, that some of the matter in the star should be superfluid. This later result really pins down the temperature at which neutron star matter becomes superfluid and the region of the star in which a certain form of superfluid exists.
ReplyDeleteI'm confused.... does the star undergo a change in temperature that brings it down to the superconducting temperatures we observe here on Earth (on the order of 4K)? Isn't that a pretty big swing from it's earlier temperature?
ReplyDeleteThat's a good question, Pamela. Superfluidity/superconductivity in terrestrial applications are caused by pairing up of electrons; in neutron stars they are due to pairing up of neutrons and (to a lesser extent protons). The superfluid transition for electrons occurs at extremely low temperatures - as you say, of order 4K - but the superfluid transition for neutrons and protons occurs at temperatures of order 10^8 - 10^9 K! The effect of pairing is actually very important in understanding 'normal' terrestrial nuclei, and is on good experimental footing, so we understand this effect pretty well. You can consider the nuclei of the atoms around us as being at least partially superfluid!
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