Penn astronomer helps NASA devise new tool to find Earth-like planets

By some estimates, there are more than 100 billion stars in the Milky Way galaxy. Like our sun, many of these stars are orbited by planets.

Over the last five years, thousands of exoplanet candidates have been detected by NASA’s Kepler satellite, part of a search for other worlds that resemble Earth and may even be hospitable to life.

A new project is taking the next step in that search. Cullen Blake, an assistant professor in the Department of Physics & Astronomy in the School of Arts & Sciences, is part of a NASA and National Science Foundation-sponsored effort to build a $10 million, cutting-edge exoplanet detector.

Over the next three years, the instrument will be built concurrently at partner institutions worldwide, led by Penn State University. In 2019, it will be installed on the 3.5 meter (11.5 feet) WIYN telescope at Kitt Peak National Observatory in Arizona.

The device is called NEID, from the word meaning “to discover/visualize” in the native language of the Tohono O’odham, a Native American tribe upon whose land Kitt Peak is located.

NEID will detect planets by the tiny gravitational tug they exert on their stars, a phenomenon known as “the wobble effect.”

“When a planet goes around a star, the star physically moves a little bit and that movement is what we’re detecting,” Blake says.

While astronomers have been using the wobble effect to detect exoplanets for several years, NEID will represent a tenfold improvement over the precision of current methods. If all goes to plan, the instrument will be able to detect stellar movements as tiny as 0.1 meters per second by using a spectrograph to measure the various component of light from the star’s photosphere. The extent to which these features shift represents the “wobble,” which is related to the mass of the orbiting planet.

“These are very challenging measurements,” Blake says. “There are some really exciting new technologies that weren’t available even a few years ago that will help us understand what is a shift in data due to the star and what could be artifacts.”

What the NEID team finds will guide NASA’s future exoplanet research, complementing information gleaned from satellite telescopes. Together, the land-based and satellite measurements can give astronomers a better sense of which planets most closely resemble Earth.

“A larger goal of this work is to identify exoplanets we might want to study further in the coming years and decades,” Blake says. “With the next generation of satellites, we might observe something about the atmospheres of these planets that would convince us that there is something beyond just volcanoes and rocks there. There might be something biological going on there, too.”