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Rare Lone Neutron Star Found Nearby
F4_W_weasel sends us to the BBC for news of the eighth lone neutron star ever discovered. It has no associated supernova remnant, binary companion, or radio pulsations. It's in our stellar neighborhood, at most 1,000 light years away. The object emits all its radiation (as far as wa can detect with current instruments) in X rays. The object is called Calvera, after the bad guy in The Magnificent Seven — which is itself the collective nickname for the seven such objects previously known.
Makes me wonder how much data has been colected, but not analyzed, and what other astronomical wonders and oddities will be found when that data is analyzed.
"I think the "new discovery" part is the "without supernova remnant". Aren't most pulsars embedded in their supernova remnants?"
While true I don't think it's exactly all that interesting that you'd find a neutron star without the remnants. There are many things that could have happened to eject such an object out of its normal position. Take a binary star system for example. If one star lost significant mass, and another gained (mass blown off of its partner) than an irregular orbit would cause the first to slingshot. That's one theory anyway.
Actually, the "new discovery" part is that we used a standard method to discover a specific class of neutron star -- the isolated, X-ray bright, radio dim class -- but found an object that, if we assumed it was a member of that class, would have placed it well outside the galactic plane. That offends theorists, mightily, since they are unlikely to be produced in SNe up there (no stars) and cool to quickly to travel there from the plane, unless this particular object is moving with a velocity much much greater than ever observed from a neutron star before (>5100 km/sec; 300 km/sec is more typical). We compared the NS with other classes we know; and it just doesn't fit well with those, with the exception of a radio pulsar whose beam does not cross our line of sight. If that is true, then Calvera's X-ray flux is such that it should be close by, perhaps the closest known neutron star. Other notes: supernovae remnants dissipate after about 10,000 years (not 10 Billion). Most of the neutron stars we've observed are not observed with their supernova remanent, but are instead radio pulsars wandering alone. I'll try to hang out a bit and field more questions.
Here's one way it *may* matter: The best explanation we have for this object, at this point, is that it is a nearby neutron star. If it is spinning rapidly (and that's an if -- we don't know how rapidly it is spinning) and it is not a perfect sphere, then it can be giving off gravitational radiation -- if, in fact, graviational radiation exists as predicted. The fact that it's nearby would make it easier to detect such radiation -- so the object is a potential target for existing gravitational wave detectors, such as LIGO. But that only matters if theories of gravity are of interest to you.