A new space-based observatory developed to detect gravitational waves might also help astronomers detect hidden objects around distant stars, paving the way toward the discovery of an entirely new population of exoplanets.
The novel planet-hunting strategy was detailed in a pair of new studies led by NASA astrophysicists involving the Laser Interferometer Space Antenna (LISA), an international mission led by the European Space Agency with participation from NASA.
Scheduled to launch in the mid-2030s, LISA’s mission will be carried out by a trio of spacecraft, whose triangular formation will span an incredible 1.6 million miles on each side, employing lasers to aid in the detection of almost indiscernible distortions in space-time.
According to the recent studies, both of which appeared in The Astrophysical Journal, LISA may be able to detect planets in orbit around small, extremely dense white dwarf stars, which comprise the remnants of stellar bodies similar to our own Sun.
“The most common source for LISA is expected to be double white dwarf systems, which are binaries composed of white dwarfs in tight orbits,” said NASA researcher Casey McGrath, in a statement this week.
Gravitational Waves from Sunlike Remnants
In binary systems where these stellar remnants orbit one another, their movement produces gravitational waves. However, once a large enough celestial object is thrown into the mix—an exoplanet, for instance—a subtle, but discernible gravitational “wobble” would become evident if the planet in question is sufficiently massive.
The resulting changes in the frequencies of the gravitational waves these white dwarf stars generate would be detectable with LISA’s sensitive instruments.
Presently, researchers estimate that the Milky Way contains as many as 10 million tightly orbiting double white dwarf systems, a vast number of which remain undetected. Once LISA goes into service, it is expected to potentially be able to resolve close to 10,000 systems like these.
Not only that, but LISA’s capabilities are also expected to help unveil an estimated 100 mixed binary systems, which contain combinations of white dwarfs, neutron stars, or black holes, that orbit in similar periods.
Additional Studies and Future Discoveries
Going forward, a second study has proposed NASA’s James Webb Space Telescope as a candidate for helping confirm additional discoveries in this area of research, mainly by helping detect excess infrared radiation emanating from planets in nearby systems.
Presently, no confirmed exoplanets have been detected in orbit around any white dwarf binary systems. In the coming years, LISA may not only change that, but it could also pave the way toward the discovery of entirely new planetary systems that existing telescopes have been unable to detect.
The two recent studies, “Receiving Exoplanet Messages with Gravitational-wave Carriers: The Gravitational-wave Radial Velocity Method,” by Casey McGrath, and “Multimessenger Exoplanets: Combining Infrared Excess and Astrometry with Gravitational-wave Detections of Double White Dwarf Exoplanets,” by McGrath with co-authors Mary Anne Limbach, Scott C. Noble, and Vincent Kofman, both appeared in The Astrophysical Journal.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.