Exotic Stellar Trio Includes Pulsar

The pulsar J0337+1715 has two white dwarf companions, one orbiting it tightly and a second close by, all packed within a space no bigger than Earth's orbit.

When it comes to cosmic exotica, pulsars are right up there. These ultradense degenerate remnants of former stars often spin hundreds of times per second. Although astronomers have spotted a couple hundred such millisecond pulsars across the Milky Way, it wasn't until January 5th that a team announced the discovery of one of these superspinning lighthouses in a triple stellar system.

An illustration of the triple millisecond pulsar with its two white dwarf companions (not shown to scale). This remarkable system apparently survived three phases of mass transfer and a supernova explosion, and yet it remained dynamically stable.
© Thomas Tauris
The pulsar, J0337+1715, has two white dwarf companions — one in a tight orbit only 3 million miles (5 million km) away and the second somewhat farther out — all packed within a space no bigger than Earth's orbit.

Scott Ransom (NRAO) and others reported the result in January 5th's online edition of Nature and at a press conference at the winter meeting of the American Astronomical Society, now under way in Washington, D.C.

Buzz has arisen over the system because astronomers hope it'll be a good place to test one aspect of Einstein's theory of gravity. Per what's called the strong equivalence principle, the outer white dwarf should have the same gravitational effect on both the inner dwarf and the pulsar. If that's not true, physics has a problem.

But such testing hasn't been done yet. For now, the more interesting aspect of the system is how it came to be. The orbits are highly circular and, what's more, in the same plane — an unlikely orientation. The trio probably formed and evolved together, but with each star dying on its own.

The one that created the neutron star went first, as a supernova. Next, roughly a billion years later, the outermost star swelled and sloughed off its outer layers to leave behind the white dwarf. Lastly, the inner star swelled, spun up the neutron star to its whirligig, 366-spins-per-second rate by pouring material onto it, and then also ended up a white dwarf.

Details beyond that basic scheme are still hazy. The team suggests that the outermost star might have engulfed the inner two when it ballooned, creating the close orbital alignment through drag. Alternately, Thomas Tauris (Max Planck Institute for Radio Astronomy and the Argelander Institute for Astronomy, Germany) and Ed van den Heuvel (University of Amsterdam) posit that the pulsar's progenitor swelled up and engulfed (at least partially) the other two stars. In their scenario, published online January 6th in Astrophysical Journal Letters, the outermost star dumps material onto the inner system instead of engulfing them.

The fact that the pulsar J0337+1715 has survived three phases of stellar swelling and a supernova explosion is incredible — "a truly remarkable journey for a triple system," as Tauris and van den Heuvel note in their conclusion. You can find more details in the press releases here and here.

References:

S. M. Ransom et al. "A millisecond pulsar in a stellar triple system." Nature, 5 January 2014.

T. M Tauris and E. P. J. van den Heuvel. "Formation of the galactic millisecond pulsar triple system PSR J0337+1715 — a neutron star with two orbiting white dwarfs." Astrophysical Journal Letters, 6 January 2014.

CATEGORIES
Cosmology, News

About Camille M. Carlisle

Assistant Editor Camille M. Carlisle covers science news for Sky & Telescope. She specializes in black holes, galactic cosmology, and whatever she happens to be writing about at the time.

6 thoughts on “Exotic Stellar Trio Includes Pulsar

  1. Gregg Weber

    To measure this I suspect that the speed of a Gravity Wave, like any ocean wave is important. The speed can’t be infinate else there would be no wave, just a uniform rising and lowering throughout the universe based on distance from the source.

    I would suspect Speed of Light but it could be some other speed.

    Another method of seeing the effect of the speed of gravity would be to find the earliest accurate measurment of some planet and see if the speed had an affect that could be seen above the "noise" through the years. Like measuring the accuracy of a clock by looking at it’s tick tocks and comparing the last to the first way back in time. Are they in sync?

  2. R. Oldershaw

    Perceptive readers will note that the total mass of this system is 2.04541 solar mass (see original paper), and that this value agrees with one of Discrete Scale Relativity’s predicted quantized masses (2.03 solar mass) for the total masses of bound stellar systems at the 99.2% level.

    If you look at Southworth’s catalog for detached binary star systems and consider the newest data (2012 to the present), you will find 18 binary star systems that are within less than 0.02 solar mass of a predicted quantized multiple of 0.145 solar mass, as opposed to only 3 binary star systems that deviate by more than 0.05 solar mass.

    Quantized masses for the total masses of bound stellar systems may be a radical and highly unexpected phenomena, but it was definitively predicted by Discrete Scale Relativity, and nature is slowly vindicating this prediction as new high quality results become known.

    Robert L. Oldershaw
    http://www3.amherst.edu/~rloldershaw
    Discrete Scale Relativity/Fractal Cosmology

  3. R. Oldershaw

    Perceptive readers will note that the total mass of this system is 2.04541 solar mass (see original paper), and that this value agrees with one of Discrete Scale Relativity’s predicted quantized masses (2.03 solar mass) for the total masses of bound stellar systems at the 99.2% level.

    If you look at Southworth’s catalog for detached binary star systems and consider the newest data (2012 to the present), you will find 18 binary star systems that are within less than 0.02 solar mass of a predicted quantized multiple of 0.145 solar mass, as opposed to only 3 binary star systems that deviate by more than 0.05 solar mass.

    Quantized masses for the total masses of bound stellar systems may be a radical and highly unexpected phenomena, but it was definitively predicted by Discrete Scale Relativity, and nature is slowly vindicating this prediction as new high quality results become known.

    Robert L. Oldershaw
    http://www3.amherst.edu/~rloldershaw
    Discrete Scale Relativity/Fractal Cosmology

  4. Peter Wilson

    “…the outer white dwarf should have the same gravitational effect on both the inner dwarf and the pulsar. If that’s not true, physics has a problem.” Seriously? Physicists are questioning the Equivalence Principle (EP)? From the 2nd press release: "Virtually all alternatives to General Relativity hold that (the EP) will not (remain true)." Oh. I get it. Alternatives to GR, which incorporate quantum mechanics, violate the EP, so they’re looking for a violation of the EP, to decide which among the alternatives to GR is best. Hmm…

  5. Robert L. Oldershaw

    Nature is reporting today (1/7/14) the discovery of a Red Giant star with what appears to be a neutron star in its core.

    Please note that Discrete Scale Relativity predicted decades ago that this is a common stellar phenomenon: all stars have neutron-star-like nuclei in their cores, just like atoms, because stars are self-similar to atoms. The Universe is a discrete fractal cosmos.

    See definitive prediction #11 at: http://www.academia.edu/2917630/Predictions_of_Discrete_Scale_Relativity

    Robert L. Oldershaw

    http://www3.amherst.edu/~rloldershaw

    Discrete Scale Relativity/Fractal Cosmology

  6. Robert L. Oldershaw

    Nature is reporting today (1/7/14) the discovery of a Red Giant star with what appears to be a neutron star in its core.

    Please note that Discrete Scale Relativity predicted decades ago that this is a common stellar phenomenon: all stars have neutron-star-like nuclei in their cores, just like atoms, because stars are self-similar to atoms. The Universe is a discrete fractal cosmos.

    See definitive prediction #11 at: http://www.academia.edu/2917630/Predictions_of_Discrete_Scale_Relativity

    Robert L. Oldershaw

    http://www3.amherst.edu/~rloldershaw

    Discrete Scale Relativity/Fractal Cosmology

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