Death is an inescapable fact of life, and stars are no exception. Eventually stars burn through their nuclear fuel and die - even our sun has an expiration date.
But a pair of burnt-out white dwarf stars are finding a scientific afterlife, enabling astrophysicists to indirectly observe gravitational waves - faint ripples in the fabric of spacetime that travel outward, much like tossing a stone in a still pond.
Gravitational waves were first predicted by Einstein's general theory of relativity in 1916. At the time, we didn't have the technology to detect them, since they are very weak and fade very quickly, although scientists found indirect evidence in the radio wave regime of their existence in observations of a binary pulsar - work that won the Nobel Prize in Physics in 1993.
These waves should be detectable by a a gravitational wave detector - namely, the upgraded Laser Interferometer Gravitational Observatory (LIGO), which has been searching space for gravity waves since it opened in 2002. LIGO is a joint project between scientists at MIT, Caltech, and many other colleges and universities.
Originally, NASA planned to build a similar gravitational wave detector in space, dubbed LISA (Laser Interferometer Space Antenna), but tightened funding led to the agency scrapping those plans last year. A similar fate befell the European Space Agency's scaled-down version, the New Gravitational Wave Observatory (although Cosmic Variance reports some intriguing rumors that we still may see such a detector in the next wave of ESA projects).
Until (if) such a project transpires, astrophysicists are looking for alternative methods to detect gravitational waves, such as the merging of binary neutron stars.
Now astronomers have confirmed more indirect evidence in the optical regime of gravitational waves emitting from a pair of dead white dwarf stars. Their results will appear in The Astrophysical Journal Letters.