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Dead Star Warps Light of Companion Red Star, Astronomers Say
04.05.2013
white dwarf crossing in front of a small, red star
An artist's concept depicts a dense, dead star called a white dwarf crossing in front of a small, red star. The white dwarf's gravity is so great that it bends and magnifies light from the red star, causing it to appear bigger than it really is. (Credit: NASA/JPL-Caltech)

See full article in Science Daily.

Excerpt: NASA's Kepler space telescope, in concert with Cornell-led measurements of stars' ultraviolet activity, has observed the effects of a [white dwarf] star bending the light of its companion red star.

The findings are among the first detections of this effect -- a result predicted by Einstein's theory of general relativity -- in binary, or double, star systems.

...While the tiny white dwarf is physically smaller than the red dwarf, it is more massive. When the white dwarf passed in front of its star, its gravity caused the starlight to observably bend and brighten.

...The research team used Cornell-led ultraviolet measurements of the star called (Kepler Object of Interest) KOI-256 taken by the Galaxy Evolution Explorer (GALEX), a NASA space telescope operated by Caltech. The GALEX observations were conducted by Cornell researchers Jamie Lloyd, associate professor of astronomy and of mechanical and aerospace engineering; Kevin Covey, former postdoctoral associate now at Lowell Observatory; and Lucianne Walkowicz of Princeton University and Evgenya Shkolnik of Lowell Observatory.

Still in early phases and for which Cornell students are now being recruited by Lloyd, the GALEX program measures ultraviolet activity in all the stars in the Kepler field of view -- an indicator of potential habitability for planets.

...Kepler's primary job is to scan stars in search of orbiting planets. As the planets pass by, they block the starlight by miniscule amounts, which Kepler's sensitive detectors can see.

So far, Kepler has identified more than 2,700 planet candidates. Still ongoing is the mission's search for planets similar to Earth in size and temperature that orbit a star like our sun. Ultimately, Kepler will reveal how common Earth-size planets are in the Milky Way galaxy.

...In this new study, scientists used gravitational lensing to determine the mass of the white dwarf. By combining this information with all the data they acquired, they were able to accurately measure the mass of the red dwarf and the physical sizes of both stars.

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