Tuesday, August 28, 2012 13:12

An international team, including the University of Texas, Harvard Smithsonian Astrophysical Observatory (SAO and the Instituto de Astrofisica de Canarias (IAC), has discovered that white dwarfs orbiting binary system J0651 are getting faster as predicted by general relativity theory of Einstein, and losing the energy needed to emit gravitational waves.

Credit: NASAGravitational waves, much like the recently discovered Higgs boson, are notoriously difficult to observe. Scientists first detected these ripples in the fabric of space-time indirectly, using radio signals from a pulsar-neutron star binary system. The find, which required exquisitely accurate timing of the radio signals, garnered its discoverers a Nobel Prize. Now a team of astronomers has detected the same effect at optical wavelengths, in light from a pair of eclipsing white dwarf stars.

“This result marks one of the cleanest and strongest detections of the effect of gravitational waves,” said team member Warren Brown of the Smithsonian Astrophysical Observatory (SAO).

The team discovered the white dwarf pair last year. (White dwarfs are the remnant cores of stars like our Sun.) The system, called SDSS J065133.338+284423.37 (J0651 for short), contains two white dwarf stars so close together — one-third of the Earth-moon distance — that they make a complete orbit in less than 13 minutes.

Illustration of gravitational waves
Larger image

“Every six minutes the stars in J0651 eclipse each other as seen from Earth, which makes for an unparalleled and accurate clock some 3,000 light-years away,” said study lead author J.J. Hermes, a graduate student working with Professor Don Winget at The University of Texas at Austin.

Einstein’s theory of general relativity predicts that moving objects create subtle ripples in the fabric of space-time, called gravitational waves. Gravitational waves should carry away energy, causing the stars to inch closer together and orbit each other faster and faster. The team was able to detect this effect in J0651.

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