Could this be a case similar to the “black widow pulsar” which actaully evapourated its companion star away entirely?

Or could this pulsar have formed through the merger of two white dwarf stars?

In either case, this scenario has taken place in a triple star syetem with only the sun-like star & milli-second pulsar remaining ..

Either of those options plausible &/or testable?

# Libraryguy on 15 May 2008 at 3:10 pm
Quick Question- What is the difference between a ‘cold’ and ‘hot’ neutron star?

I’m guessing time & / or temperature.

Like white dwarfs, neutron stars cannot fuse elements into energy and thus shine only by radiating away their massively hot temperatures they were born with.

A young – and hence still very* hot – neutron star would therefore be a bit different from one that has cooled down over the aeons.

The young hot neutron star or pulsar would have – usually – a far higher spin rate, immensely strong magnetic field, a searingly blue hot surface etc …

Vs

the old cold neutron star which would’ve spun down to a slower roatation or spin rate, had its magnetic field fade away a fair bit in intensity – and hence perhaps stopped pulsing, cooled down to a mere white or yellow hot surface etc .. (Ultimately, neutron stars and white dwarfs cool all the way to red heat and finally cold black dwarfs – but that will take longer than the cosmos has been around for yet! )

That’s just my guess anyway I’m not really 100% sure what you’re referring to here.

—————-
* “very” is utterly inadequate at describing the extremes in play with neutron stars, pulsars & magnetars – but then no words really come close to describing them.

The best evidence is that we actually *see* pulsars being spun up. Binary systems called high-mass X-ray binaries consist of a high-mass star and (in some cases) a pulsar, in which matter from the companion is falling on the pulsar. We can often observe the rotation of the pulsar, and what we see is that the rotation rate of the pulsar is controlled by the infalling material – as the rate of infall varies, the torque on the pulsar increases or decreases in just the way predicted by theory. Now, high-mass X-ray binaries lead to very slowly spinning pulsars, so they are not directly applicable, but they give us confidence that low-mass X-ray binaries (in which it is much more difficult to see the pulsar’s rotation) exhibit the same phenomenon. In such a case the theory predicts that the neutron star should be spun up.

As for isolated millisecond pulsars, many millisecond pulsars (and in particular many of the ones we have found) occur in globular clusters. Globular clusters are very dense, so over the (very long) lifespan of a millisecond pulsar, there is plenty of time for a third star to come along and break up a binary pair.

There are also plenty of stars available in a globular cluster to kick 1903 into an elliptical orbit – or rather, there would be, if it were in a globular cluster. But it’s not, it’s floating around loose in the galaxy. Which is one reason it’s so weird.

I would guess that the 1 in 5 pulsars that spin fast but have no companion were quite heavy to begin with, leading to high angular velocity. They should not, however, accelerate.

There has to be a better explanation for what we are observing!

BTW, given the spin rate of these objects Phil, would it be too much to make a new amusement park ride called “The Pulsar”?

“Pulsars are highly magnetized rotating neutron stars which emit a beam of detectable electromagnetic radiation in the form of radio waves. …The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name.”

Maybe the pulsar and neutron star were orbiting so close that their orbits decayed and they merged into a single object (giving off lots of gravitational radiation in the meantime). That could possibly be a reason for the mass of the pulsar being larger than usual.

Sometimes supernova explosions are fairly symmetric (spherical) and sometimes they’re pretty asymmetric. Pulsars, when they’re created, can either get very small kicks (like the Crab Pulsar), or very very large ones (up to ~1000 km/s is not rare). They can get shot out of star systems or they can barely change their orbit.

While an explosion can impart a tremendous amount of energy, if there’s a companion not all that close, it may not be disturbed so much. Why? Because even though a lot of energy is released, the amount that reaches the companion star decreases with the distance between the supernova and the companion. Since not all supernovae are created equal (more massive=bigger explosion), it won’t necessarily eject anything.

There’s no universal rule for these things; there’s a lot of variety!

Ethan

but the pulsar would probably not stay where it is, wouldn’t it?
Unfortunately I don’t know enough physics to work out all the maths involved.