By McDONALD OBSERVATORY | THE UNIVERSITY OF TEXAS AT AUSTIN
AUSTIN, Texas — A team of astronomers led by researchers from The University of Texas at Austin has confirmed the emission of gravitational waves from the second-strongest known source in our galaxy by studying the shrinking orbital period of a unique pair of burnt-out stars. Their observations tested Albert Einstein’s theory of general relativity in a new regime. The results will be published soon in The Astrophysical Journal Letters.
Last year, the same team discovered that the two white dwarf stars are so close together that they make a complete orbit in less than 13 minutes, and they should be gradually slipping closer. The system, called SDSS J065133.338+284423.37 (J0651 for short), contains two white dwarf stars, which are the remnant cores of stars like our sun.
Einstein’s theory of general relativity predicts that moving objects create subtle ripples in the fabric of space-time, called gravitational waves. Though not yet directly observed, gravitational waves should carry away energy, causing the stars to inch closer together and orbit each other faster and faster.
“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 predicts that the orbital period of this binary system loses about 0.25 milliseconds every year, less than one-thousandth of a second.
The team has just tested that prediction using more than 200 hours of observations from the 2.1-meter Otto Struve Telescope at the university’s McDonald Observatory in West Texas, the Frederick C. Gillett Gemini North telescope in Hawai‘i, the 10.4-meter Gran Telescopio Canarias in the Canary Islands of Spain, and the 3.5-meter Apache Point telescope in New Mexico.
“Compared to April 2011, when we discovered this object, the eclipses now happen six seconds sooner than expected,” said team member Mukremin Kilic of The University of Oklahoma.