back to article Meet the super-speedy white dwarf binary system that's going to grav-wave our world

Astronomers have discovered the fastest-known eclipsing white dwarf pair yet, with the dead stars whizzing around each other every 6.91 minutes, according to a Nature paper published on Wednesday. The binary system known as ZTF J1539+5027 was spotted by the Zwicky Transient Facility (which put the ZTF into its name) …

  1. Evil Harry
    Thumb Up

    It's great to know when the world is being turned upside down with politics, climate change and all that stuff, there are still people out there making these awesome discoveries.

  2. Sanctimonious Prick
    Happy

    LISA!

    Damnit! I want LISA now!

    1. Loyal Commenter Silver badge
      Coat

      Re: LISA!

      You're my future wife Lisa!

      1. BigSLitleP Silver badge

        Re: LISA!

        You're tearing me apart, Lisa!

        1. Loyal Commenter Silver badge

          Re: LISA!

          Oh hi Danny

  3. Conundrum1885 Bronze badge

    Re. LISA

    Isn't that the space based GWO ?

    Last I heard it was still being tested.

    1. John Mangan

      Re: Re. LISA

      A PoC was launched a few years back to test some of the required technologies. We are nowhere near launching the real thing - as the estimated date of 20134 demonstrates.

      1. John Mangan

        Re: Re. LISA

        I don't know where the intrusive '1' came from - it's not next to '0' or '3' on the keyboard?

        1. A.P. Veening Silver badge

          Re: Re. LISA

          It is above the zero on the numeric keypad.

        2. Rich 11 Silver badge
          Alien

          Re: Re. LISA

          I know where it came from.

        3. Symon Silver badge
          Happy

          Re: Re. LISA

          It is next to '0' on the numeric keypad. Over there ---->

  4. Martin Gregorie Silver badge

    Search method

    Surely you meant:

    "Burdge said he used algorithms sped up by GPUs to comb through optical image data to find the eclipsing binary system."

    1. tfb Silver badge
      Boffin

      Re: Search method

      Yes, that's what they meant. I've sent a correction; dunno if they will change the article. This thing is way outside anything LIGO / VIRGO could hear even if it was loud enough: they're sensitive at audio frequencies, basically, and this is hundredths of a Hz.

  5. Timbo

    Need new image...or maybe some copy editing?

    "One is slightly smaller and less bright than the other..."

    ...and yet the image shown, shows that "One is quite a bit smaller and BRIGHTER than the other..."

    1. tfb Silver badge
      Boffin

      Re: Need new image...or maybe some copy editing?

      I suspect they mean 'less luminous': its surface brightness may be higher.

      However all these images are just what someone drew of course.

    2. Brewster's Angle Grinder Silver badge

      Re: Need new image...or maybe some copy editing?

      I haven't read the paper. However I suspect the smaller one could have a lower total luminosity but a higher luminosity per unit area - hence it "appears" brighter.

  6. TechnicalBen Silver badge

    Reg units?

    What is the gravitational wave unit in Reg language? I'm thinking "number of belly flops" or "baked beans eaten" scales?

    1. Jason Bloomberg Silver badge
      Coat

      Re: Reg units?

      What is the gravitational wave unit in Reg language?

      I would think it has to be based upon the pull which Gregg's exerts on the average passerby.

      1. DJO Silver badge

        Re: Reg units?

        That would be a negative quantity.

        A less contentious value is necessary, how about the gravitational effect from a million spherical sheep (in vacuo) as a point mass.

        1. Tom 7 Silver badge

          Re: Reg units?

          mmm kebab.

        2. eldakka Silver badge
          Coat

          Re: Reg units?

          So a Gregg would be a measure of Dark Energy?

  7. Pascal Monett Silver badge

    To think

    Imagine the gigantic amount of energy that a stellar mass the size of the Sun has whipping around a twin in less than 10 minutes.

    The energy concentrated there must be simply apocalyptic.

    1. Rich 11 Silver badge

      Re: To think

      Back of fag packet calculation: the system has a total kinetic energy of about 7x10^41 joules, packed into a volume of space about the size of Saturn.

    2. John Brown (no body) Silver badge
      Boffin

      Re: To think

      Yes, it's staggeringly, mind-boggling. So close that they revolve around each other in under 7 minutes and yet it's estimated they are still 200,000 years from merging. To those of use with little to no knowledge of stellar engineering, I'd have more of a sense that colliding with each other was imminent on a human scale.

      1. Brewster's Angle Grinder Silver badge

        Re: To think

        "...a sense that colliding with each other was imminent on a human scale."

        200,000 years is human scale. I mean you hairy apes have been around that long, haven't you? Most things in astronomy have timescales of billions of years.

        They're probably only going to collide because of gravitational losses, which are obviously small and so slow. Without that they'd be as stable as an electron orbiting an atom.

  8. Duncan Macdonald Silver badge
    Mushroom

    Supernova ?

    When the two merge will it trigger a supernova explosion? One of the causes for a type 1a supernova explosion is thought to be the merge of two white dwarf stars.

    Icon for the effect ==================>

    1. tfb Silver badge
      Boffin

      Re: Supernova ?

      It turns out that no, there won't. You are completely correct about the origin of type 1a supernovae, but the two white dwarves here are not massive enough. The Nature letter (which seems to now be showing me the actual PDF of the thing even though it was not earlier) says that the two masses are 0.610 and 0.210 solar masses, while the upper limit for a white dwarf is 1.44 solar masses. So even after colliding they will be comfortably below the limit.

      1. annodomini2

        Re: Supernova ?

        What about a nova?

  9. el kabong Silver badge
    Alien

    Those gravity waves, when will it start?

    If someone is going to grav-wave my world I want to be ready to take it.

    Do they have any schedule yet?

    1. John Brown (no body) Silver badge
      Thumb Up

      Re: Those gravity waves, when will it start?

      surfs up, dude!

  10. tfb Silver badge
    Boffin

    Another potential test of GR

    One interesting thing about this binary: if the predicted merger time is 200,000 years away then it ought to be possible to detect the orbital changes over time as the orbits decay due to gravitational waves. This was famously done for the Hulse-Taylor binary which provided an indirect test for the existence of gravitational waves. That has a spin-down time of 300,000,000 years: this is shorter by a factor of about a thousand.

    One problem is that these things are not pulsars, so there's no very precise timing information as there is for a pulsar: you'd have to work from the light curves. That might make it impossible to detect, although presumably with sufficiently long-term observations you could do a lot better.

    (And this also isn't really a new test, although I think it would be interesting to confirm that relatively normal objects like white dwarves (normal compared to neutron stars...) have decaying orbits as well.)

    1. tfb Silver badge
      Boffin

      Re: Another potential test of GR

      And of course they've beaten me to it. The orbit is decaying, and the rate of decay does agree with GR. There's a nice plot on the second page of the paper.

      Pesky astronomers, stealing ideas from my brain before I'd thought of them.

  11. Stevie Silver badge

    Bah!

    Something's off. In one paragraph it says that the frequency of the gravity waves is too low to be detected until a new interferometer is deployed in fourteen years, and in the next it talks about discovering the pair from examining gravity wave data.

    WTF?

    1. tfb Silver badge
      Boffin

      Re: Bah!

      That was an error: it was discovered from light-curve data, and yes it is too slow (and probably also just too weak) for LIGO/VIRGO to hear.

      1. Stevie Silver badge

        Re: Bah!

        Thanks for the explanation.

        Not sure why I was downvoted for my comment.

        1. tfb Silver badge

          Re: Bah!

          Me neither, but votes here are odd, and there are an essentially unbounded number of trolls who lurk around the forums.

  12. Mark 85 Silver badge

    This confuses me....

    Astronomers have discovered the fastest-known eclipsing white dwarf pair yet, with the dead stars whizzing around each other every 6.91 minutes,

    If they're white dwarfs, then obviously they're still "burning" and not dead yet. Or is there a definition of "dead" that I missed.

    1. VeganVegan
      Flame

      Re: This confuses me....

      White dwarfs have ceased nuclear fusion, hence dead.

      They remain luminous as they cool down from the extreme temperatures (1E7 K) reached at the end of their fusion lives, much like a heated lump of metal remains luminous for a while after being withdrawn from the heating source.

      1. tfb Silver badge
        Boffin

        Re: This confuses me....

        One interesting thing is how long it takes white dwarves to cool. The answer is 'long': the end state of a white dwarf once it has cooled is a thing called a black dwarf, and it's estimated that there are no black dwarves yet, because the universe is not old enough.

        I think the estimated time for them to get really cool is ~ 1E15 years, but some may last much longer than this.

  13. Potemkine! Silver badge

    What is the distance between the two stars?

  14. DeeCee

    Now if the scientists could finally cure aging and death

    i might even see it...

  15. WaveyDavey

    Two bodies roughly the size of earth whizzing around each other every 6 and a bit minutes: those buggers are moving really fast. Anyone got a fag-packet estimate for speed (not velocity) ?

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