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Friday
Jul152011

Highlight: A Tight White Dwarf System

A group of astronomers led by Warren Brown at the SAO has discovered a white dwarf-white dwarf binary system in which the two white dwarfs orbit each other every 12.75 minutes.

Why is that interesting/kind of crazy?
a) Because white dwarfs are on the order of the mass of the sun but the size of the earth. Stars not massive enough to become neutron stars in their golden, geriatric years become white dwarfs, after they become red giants and after those red giants are unable to fuse carbon. White dwarfs are supported by electron degeneracy pressure, meaning that the electrons could not squish any closer together or they would occupy the same energy states, which violates the Pauli Exclusion Principle, which exists solely to say that particles can't do that. Anyway, these two white dwarfs happen to be low-mass (0.25 solar masses and 0.55 solar masses), and it is because of that low mass that they are in such a compact orbit. Imagine two things the size of the earth but much, much, much more massive orbiting around each other in the time it takes to watch half an episode of Two and a Half Men. Is it still cool to make Charlie Sheen jokes?

b) The binary system is "clean": material is not being transferred from one star to another, despite their proximity.

NASA's propaganda desktop background for LISA, which still exists despite
the sobering statements on the LISA homepage about how LISA will not be
built by NASA in any near-type future.
c) The team predicts that gravitational wave radiation should be causing the WDs' orbit to shrink, sending them closer and closer to each other; the system will become "unclean" in about 900,000 years, which is super-short on astronomical time scales. The end state of that contact is an open question.

d) The system produces gravitational waves that would be detectable by instrumentation that we are currently capable of building (if only the $$ were flowing). Einstein's theory of General Relativity predicts that massive objects (especially those in dynamic systems) should produce ripples in the famed "fabric of spacetime," if it is indeed the kind of fabric Einstein and 99% of subsequent scientists believe(d), in the same way that dropping a watermelon into a pool produces waves. LISA, the Laser Interferometry Space Antenna, could detect gravitational waves from this system within a week of its existence. Given that the discovery of gravitational waves will probably earn the discoverer a Nobel Prize, this WD system is historically significant. You may always remember where you were when you heard about its existence, and divide your life into "the time before I read about the tight white dwarf binary" and "the time after I read about the tight white dwarf binary."

ResearchBlogging.orgWarren R. Brown, Mukremin Kilic, J. J. Hermes, Carlos Allende Prieto, Scott J. Kenyon, & D. E. Winget (2011). A 12 minute Orbital Period Detached White Dwarf Eclipsing Binary Astropyhsical Journal Letters arXiv: 1107.2389v1

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References (3)

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  • Response
    Response: similar website
    Summary and analysis of new scientific discoveries in biology and astronomy. by Sarah Scoles and Brooke Napier.
  • Response
    The wide system can be showed through the different timing. This is only and also compulsory element for everyone. This is too much valuable things for everyone.
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    Response: Ola Free Rides

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