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Hungry Millisecond Pulsar Found Feeding

Posted by michael on from the yum-yum dept.

Gopher971 writes: "The latest joint discovery by the Hubble Telescope is a Millisecond Pulsar feeding off of it's companion Red Giant star. Scientists have long speculated on how Milli Pulsars formed and now have proof to back up their claims. See the UniSci link and The Irish Times link."

8 of 15 comments (clear)

  1. is that... no.... by elroyjenkins · · Score: 2, Interesting

    A link to an artists representation of the process...


    tee hee... tell me that "object" in the middle isnt a sperm, geez...
    did disney make the pic or something?

    --
    Did you just grab my ass?
  2. Hmmm, blackhole by Gyl · · Score: 2, Interesting

    So, does anybody out there know enough about astrophysics to know how close this thing would be to becoming a black hole? THAT would be a cool process to watch. Basically, the question is, how massive is the pulsar, and how much stuff is it sucking up from the companion star?

    1. Re:Hmmm, blackhole by Spamalamadingdong · · Score: 2
      So, does anybody out there know enough about astrophysics to know how close this thing would be to becoming a black hole?
      Nothing in the article hinted at that.
      THAT would be a cool process to watch.
      ... from a safe distance of several light-years (mind the neutrinos, they don't care about shielding).

      This pulsar is in a globular cluster, which probably contains a number of other neutron stars already. Sooner or later two of them are going to make close passes and get captured into a mutual orbit, which will then decay. When the two neutron stars merge they will likely collapse catastrophically into a black hole, with the added excitement of kilohertz gravitational waves thrown in.

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      Scientists restrict study to entire physical universe; creationist
    2. Re:Hmmm, blackhole by CheshireCatCO · · Score: 2
      how close this thing would be to becoming a black hole?

      Not very, I would guess. Neutron stars tend to have masses just at or near the Chandrasaker limit (actually, sometimes a bit lower, even). That's 1.4 solar masses. A neutron star becomes a black hole at between 2 and 3 solar masses (number uncertain). So that's a fair margin, particularly if you take the 3 solar mass limit.

      Now, how much matter is transfered? If the neutron star is 1.4 solar masses, if it is typical size (10 km radius) and if the companion is 1 AU from the neutron star, you'd have to transfer about 2.5 X 10-5 solar masses to make a millsecond pulsar, I'm figuring. That's a tiny amount. The mass tranfer required goes like 1/r2 (until the mass transfered is a large fraction of the pulsar's inital mass, anyway). So even at 0.1 AU, it's still only 1/1000 of a solar mass. (0.1 AU = 10 solar radii, roughly) They'd almost have to be in physical contact to require enough mass transfer to push the neutron star over the black hole limit.

    3. Re:Hmmm, blackhole by AndroidCat · · Score: 2

      A supernova in the solar system would kill anyone out to Jupiter just with the neutrinos. (Of course, if you survived that, your problems are just begining!) They interact very weakly with other matter, but when ya gets that many of the buggers...

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  3. Two theories by marcus · · Score: 5, Interesting

    I'm not really up-to-date, but...

    Both say that the material will pile up on the surface until it reaches fusion temperatures and then start to burn.

    One says that the burn will be fast and explosive, blowing all the rest of the new, degenerate and normal matter off of the surface. An extension of this idea suggests that the explosion, since it is very unlikely to be symmetrical and simultaneous all over the surface of the neutron star, will disrupt and break up the neutron star itself. We are talking about a big, nova or supernova class explosion here.

    The other says that the fusion burn will be slow, intermittent or periodic, something more like a continuous series of neutron star sized burps and blow stuff off here and there and simply heat things up. The heat and radiation from the explosions slows the infall of matter, a form of negative feedback, so that the process is self throttling. Somewhere along the way, it might accumulate enough to collapse, otherwise the process just continues until the donor star "runs out of gas" and then everything calms down.

    There are nuances to both depending on the rate of deposition, spin, size of the original neutron star, etc.

    Mostly there's just not enough data to tell, perhaps both happen depending on the situation.

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    Good judgement comes from experience, and experience comes from bad judgement.
    - W. Wriston, former Citibank CEO
  4. The first theory sounds incorrect by Spamalamadingdong · · Score: 2, Informative
    One says that the burn will be fast and explosive, blowing all the rest of the new, degenerate and normal matter off of the surface.
    Where'd that theory come from? I've been reading about neutron stars for some time and I've seen this as an explanation for X-ray bursters (the ignition of the accumulated hydrogen makes the surface extremely hot for a while, then it cools), but the star does not lose matter; the energy of fusing hydrogen is not sufficient to overcome the gravity of a neutron star.

    That sounds more like a certain theory for the collapse of white dwarfs under infalling matter. Supposedly this would always happen at the same mass and produce uniformly bright supernovae.

    --
    Scientists restrict study to entire physical universe; creationist
  5. Globular Clusters! by s0l0m0n · · Score: 2, Informative

    Sounds like a sick snack, don't it.

    here's a link to Globular Cluster NGC6397

    Can you find the pulsar? *grin*

    Photo taken from the Hubble, circa 1994.