Results 1 to 6 of 6

Thread: Can a neutron star or black hole initiate a type 1a supernova?

  1. #1
    Join Date
    Nov 2004
    Posts
    5,616

    Can a neutron star or black hole initiate a type 1a supernova?

    You always hear about white dwarfs doing it, why can't neutron stars or black holes?

    Also, what happens when two white dwarfs collide?
    "Occam" is the name of the alien race that will enslave us all eventually. And they've got razors for hands. I don't know if that's true but it seems like the simplest answer."

    Stephen Colbert.

  2. #2
    Join Date
    May 2003
    Posts
    6,146
    Quote Originally Posted by parallaxicality View Post
    You always hear about white dwarfs doing it, why can't neutron stars or black holes?
    Well the current consensus model of a type Ia supernova is that as a white dwarf gradually accretes matter from a companion, the temperature and pressure eventually reach the point where carbon fusion is possible, and most of the star undergoes fusion all at once, releasing a huge burst of energy. But a neutron star isn't composed of carbon (or anything else) that could undergo fusion to release energy; in fact it's a remnant of a supernova explosion. Material falling on the surface of a neutron star usually just gives a burst of intense radiation immediately from the force of the impact, and is immediately compressed to the density of the neutron star. It won't build up to a limit the way matter falling onto a white dwarf does (although in principle, if it were to accrete enough matter, it would become a black hole; for the most part, we don't think this would cause an explosion, but might have a gravitational wave signature). As for a black hole, anything falling in is trapped there, and never escapes, with the black hole just becoming larger. You'd never get an explosion caused by matter building up.

    Quote Originally Posted by parallaxicality View Post
    Also, what happens when two white dwarfs collide?
    It's believed that this could also trigger a type Ia supernova, as the total mass gets pushed over the mass limit for a white dwarf. These should be pretty rare, but there are a few events that look like they could have been triggered by white dwarf mergers.
    Last edited by Grey; 2020-May-28 at 02:04 PM. Reason: Corrected spelling.
    Conserve energy. Commute with the Hamiltonian.

  3. #3
    Join Date
    Nov 2004
    Posts
    5,616
    As for a black hole, anything falling in is trapped there, and never escapes, with the black hole just becoming larger. You'd never get an explosion caused by matter building up.
    But black holes can form quasars. Is it possible for a quasar to explode if enough matter collects in one area in a short time?
    "Occam" is the name of the alien race that will enslave us all eventually. And they've got razors for hands. I don't know if that's true but it seems like the simplest answer."

    Stephen Colbert.

  4. #4
    Join Date
    Jul 2005
    Posts
    19,291
    Quote Originally Posted by parallaxicality View Post
    But black holes can form quasars. Is it possible for a quasar to explode if enough matter collects in one area in a short time?
    Quasars self-regulate at close to the Eddington limit. As you add more mass to the accretion disc, its luminosity increases until the radiation pressure is sufficient to blow any further infalling material away from the disc, against gravity. So you'd have to find a natural process that actually fires material into the disc with a high inward velocity.

    Grant Hutchison

  5. #5
    Join Date
    May 2003
    Posts
    6,146
    It's also worth noting that the luminosity of a type Ia supernova peaks at about 5 billion solar luminosities, while a typical quasar is already at a few trillion solar luminosities, or a couple orders of magnitude higher for the brightest ones. That is to say, a quasar is already producing far more energy than a supernova.
    Conserve energy. Commute with the Hamiltonian.

  6. #6
    Join Date
    Jul 2005
    Location
    Massachusetts, USA
    Posts
    22,081
    Grey, in post #2 comes closest to my answer, so just elaborating: for the single degenerate model of Type 1a, no. For the double degenerate model (Note: when two white dwarfs merge, it is called double degenerate and creates a Type 1a SN), IIRC, that LIGO has observed a black hole white dwarf merger, and there was no SN associated with it. Let's look at a low mass neutron star merging with a high mass white dwarf... This would be a disruptive event certainly, the question is could it suddenly inspire all of the Carbon and Oxygen nuclei of the white dwarf to fuse into Cobalt and Nickel (yielding the decay curve of the light from a classic Type 1a)? I'm not sure, but suspect not. Without setting up a computer model and running it, my guess is that some considerable amount of fusion would go on at the neutron star's surface but that this would be localized and would blast away the white dwarf material near the NS in its spiral into the white dwarf, creating something looking like the Cat's Eye nebula. It would be fairly bright while the white dwarf was being destroyed, but not supernova bright. Probably not even kilonova bright.

    On a related topic, IF a black hole were to be on a trajectory into the center of a large star that was still mostly Hydrogen, it would probably create an explosion with about the energy output of a supernova, but it wouldn't be a Type 1a, and would have a very different light curve.
    Forming opinions as we speak

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •