This pair of white dwarfs is spinning out gravitational waves

A binary white dwarf in a tight, super-fast rotation looks to be pumping out gravitational waves.

This pair of white dwarfs is spinning out gravitational waves
Image source: Weiss/Shutterstock/Big Think
  • General relativity predicts white-dwarf binaries can do this, and now one has been found.
  • The binary is a perfect candidate for a massive new gravitational-wave detector being deployed.
  • The new LISA detector is a constellation of three satellites positioned millions of miles apart.

    • Last spring, the National Science Foundation's Laser Interferometer Gravitational-Wave Observatory (LIGO) detected a gravitational wave produced by the collision of two huge black holes 3 billion years ago. Einstein had predicted such waves, powerful and extraordinarily subtle perturbations in spacetime, but never before had one been detected.

      Though LIGO's feat was history-making, a new, even more sensitive detection system is planned for deployment in the near future. Fortunately, scientists believe the generation of gravitational waves doesn't require such a massive and rare cataclysm as the one detected by LIGO. One particular binary pair of white dwarf stars locked in a super-tight orbit, J2322+0509, may be sufficient to do the trick, producing, as they spin into a death spiral, gravitational waves strong enough to be detected by the new system once it's up and running.


      Artist's conception of newly discovered binary white dwarf gravitational source of gravitational waves

      Image source: M. Weiss/Harvard/Smithsonian

      J2322+0509 is a white binary system, remnants of two stars that have exhausted their fuel, leaving nothing much but their helium cores. They're locked together in an ever-narrowing death spiral that will reach its final stage millions of years from now. However, as we observe them now, they're orbiting in startlingly close proximity, each dwarf completing its orbit of the other in just 20 minutes plus 1 second. That's the third-shortest orbital period astronomers have yet seen — the record-holder is ZTF J1539+5027, nicknamed J1539, a pair with an orbital period of just 6.91 minutes.

      In any event, general relativity predicts that rapidly spinning white dwarf stars can produce gravitational waves, as can a few other things: the speedy rotation of neutron stars, and the explosion of supernovae. Astronomer Warren Brown says he sees the requisite scenario playing out with J2322+0509: "This pair is at the extreme end of stars with short orbital periods. And the orbit of this pair of objects is decaying." This fits with its emanation of gravitational waves: "The gravitational waves that are being emitted are causing the pair to lose energy; in 6 or 7 million years they will merge into a single, more massive white dwarf."

      The new gravitational-wave system

      Artist's impression of the three LISA spacecraft

      Image source: ESA/EADS Astrium

      The new system for detecting gravitational waves is called the Laser Interferometer Space Antenna, or LISA, and it will be launched in 2034. LISA will be a triangular constellation of three satellites 50 million kilometers behind Earth as it orbits the Sun, and positioned 2.5 million km apart from each other. They'll be "connected" by laser beams bounced back and forth between them, forming a gigantic interferometer-based detector. The distortion of spacetime produced by a gravitational wave passing through the lasers will perturb the pattern they create to some tiny, likely subatomic degree, allowing LISA to detect and study that wave.

      Perfect for LISA

      Schematic illustration of the LISA array's orbit as it revolves with the Earth around the Sun in one year.

      Image source: ESA

      In order for LISA to deliver on its scientific promise, of course, some gravitational waves will have to ripple its way fairly soon in order to verify that it's working as hoped. Astrophysicist Mukremin Kilic says, "Verification binaries are important because we know that LISA will see them within a few weeks of turning on the telescopes." Serving as a test run of sorts, "This detection provides an anchor for those models, and for doing future experiments so that we can find more of these stars and determine their true numbers."

      Finding J2322+0509 poses something of a relief to scientists. Although it's believed that white dwarf binaries are common, she says, "There's only a handful of LISA sources that we know of today."

      Especially exciting about this binary is its orientation toward us and what that may signify as to the strength of gravitation waves it emits. "This binary was difficult to detect," says Brown, "because it is oriented face-on to us, like a bull's eye, rather than edge-on. Remarkably, the binary's gravitational waves are 2.5 times stronger at this orientation than if it were orientated edge-on like an eclipsing binary."

      Brown concludes, "We're finding that the binaries that might be the hardest to detect may actually be the strongest sources of gravitational waves."

      ‘Designer baby’ book trilogy explores the moral dilemmas humans may soon create

      How would the ability to genetically customize children change society? Sci-fi author Eugene Clark explores the future on our horizon in Volume I of the "Genetic Pressure" series.

      Surprising Science
      • A new sci-fi book series called "Genetic Pressure" explores the scientific and moral implications of a world with a burgeoning designer baby industry.
      • It's currently illegal to implant genetically edited human embryos in most nations, but designer babies may someday become widespread.
      • While gene-editing technology could help humans eliminate genetic diseases, some in the scientific community fear it may also usher in a new era of eugenics.
      Keep reading Show less

      Octopus-like creatures inhabit Jupiter’s moon, claims space scientist

      A leading British space scientist thinks there is life under the ice sheets of Europa.

      Jupiter's moon Europa has a huge ocean beneath its sheets of ice.

      Credit: NASA/JPL-Caltech/SETI Institute
      Surprising Science
      • A British scientist named Professor Monica Grady recently came out in support of extraterrestrial life on Europa.
      • Europa, the sixth largest moon in the solar system, may have favorable conditions for life under its miles of ice.
      • The moon is one of Jupiter's 79.
      Keep reading Show less

      Lair of giant predator worms from 20 million years ago found

      Scientists discover burrows of giant predator worms that lived on the seafloor 20 million years ago.

      Bobbit worm (Eunice aphroditois).

      Credit: Jenny – Flickr
      Surprising Science
      • Scientists in Taiwan find the lair of giant predator worms that inhabited the seafloor 20 million years ago.
      • The worm is possibly related to the modern bobbit worm (Eunice aphroditois).
      • The creatures can reach several meters in length and famously ambush their pray.
      Keep reading Show less

      FOSTA-SESTA: Have controversial sex trafficking acts done more harm than good?

      The idea behind the law was simple: make it more difficult for online sex traffickers to find victims.

      Has FOSTA-SESTA really lived up to it's promise of protecting sex trafficking victims - or has it made them easier to target?

      Credit: troyanphoto on Adobe Stock
      Politics & Current Affairs
      • SESTA (Stop Enabling Sex Traffickers Act) and FOSTA (Allow States and Victims to Fight Online Sex Trafficking Act) started as two separate bills that were both created with a singular goal: curb online sex trafficking. They were signed into law by former President Trump in 2018.
      • The implementation of this law in America has left an international impact, as websites attempt to protect themselves from liability by closing down the sections of their sites that sex workers use to arrange safe meetings with clientele.
      • While supporters of this bill have framed FOSTA-SESTA as a vital tool that could prevent sex trafficking and allow sex trafficking survivors to sue those websites for facilitating their victimization, many other people are strictly against the bill and hope it will be reversed.
      Keep reading Show less

      What is the ‘self’? The 3 layers of your identity.

      Answering the question of who you are is not an easy task. Let's unpack what culture, philosophy, and neuroscience have to say.

      Scroll down to load more…