Laser-Wielding Robot Probes Exoplanet Systems

The automated observations taken with Robo-AO, color coded by scientific project. The dense red cluster in the upper left is the Kepler field. Credit: Robo-AO Collaboration.

The IfA’s Christoph Baranec is leading a team that uses the world’s first robotic laser adaptive optics system—Robo-AO— to explore thousands of exoplanet systems (planets around other stars) at resolutions approaching those of the Hubble Space Telescope. The results, published in the Astrophysical Journal, shed light on the formation of exotic exoplanet systems and confirm hundreds of exoplanets.

Terrestrial telescopes use laser adaptive optics systems to remove the image-blurring effects of Earth’s turbulent atmosphere, thereby capturing much sharper images than are otherwise possible from the ground. Baranec, Robo-AO’s principal investigator, led the development of the innovative Robo-AO system on the Palomar 1.5-meter telescope. It is the world’s first instrument that fully automates the complex and often inefficient operation of laser adaptive optics.

“We’re using Robo-AO’s extreme efficiency to survey in exquisite detail all of the candidate exoplanet host stars that have been discovered by NASA’s Kepler mission,” said Baranec. “While Kepler has an unrivaled ability to discover exoplanets that pass between us and their host star, it comes at the price of reduced image quality, and that’s where Robo-AO excels.”

In fact, analysis of the first part of the Robo-AO/Kepler exoplanet host survey is already yielding surprising results. “We’re finding that ‘hot Jupiters’—rare giant exoplanets in tight orbits—are almost three times more likely to be found in wide binary star systems than other exoplanets, shedding light on how these exotic objects formed,” said Nicholas Law (University of North Carolina at Chapel Hill), Robo-AO’s project scientist. “Going further, Robo-AO’s unique capabilities have allowed us to discover even rarer objects: binary star systems where each star has a Kepler-detected planetary system of its own. These systems will be uniquely interesting for studies of how the planets formed—and for science fiction about what life would be like with another planetary system right next door,” continued Law.

Indeed, the first Robo-AO survey, covering 715 Kepler candidate exoplanet hosts, is the single largest scientific adaptive optics survey ever. That record won’t stand for very long, as the Robo-AO team is extending the survey to image each and every of the 4,000 Kepler candidate exoplanet hosts, and is ready to observe exoplanet hosts from Kepler’s new K2 mission as they are discovered.

The key to Robo-AO’s success is its efficiency, allowing it to observe hundreds more targets per night than conventional adaptive optics systems. So far, the Robo-AO system has been used to make over 13,000 observations. “The automation of laser adaptive optics has allowed us to tackle scientific questions that were unimaginable just a few years ago. We can now observe tens of thousands of objects at Hubble-Space-Telescope-like resolution in short periods of time,” Baranec said. “Now that the technology has been proven, we’re looking to bring it to the pristine skies of Maunakea, Hawai‘i, where it will be even more powerful.”

The other members of the Robo-AO team include researchers from Princeton, Caltech, the University of North Carolina, Harvard, and the Inter-University Centre for Astronomy and Astrophysics in Pune, India, and a student at W. Tresper Clarke High School in Westbury, New York.