Astrophysics Ph.D. Student Discovers New Solar System Published: February 13, 2015 By: Melissa Hellmann An artist’s rendition of the Kepler spacecraft. Image credit: NASA / Wendy Stenzel Bay-Area native Erik Petigura, a 5th year doctoral student in Astrophysics, became interested in astronomy at five years old when he watched Carl Sagan’s T.V. series, Cosmos. As an undergrad at Berkeley, he double-majored in Physics and Astrophysics, with the goal of gaining a better understanding of the planets outside of our system. In January, Petigura made the remarkable discovery of a new solar system with one planet that is very similar to our own. By analyzing data from NASA’s Kepler Space Telescope, Petigura identified three planets that orbit the star Epic 201367065 — which is half the size of the Sun. The outer-most planet in the system is just slightly bigger than the size of the Earth and receives only 40% more sunlight. “This is one of the most Earth-like planets known to date,” Petigura says. “It means that the potential for atmospheric chemistry and perhaps even life on this planet is very interesting and worth following up on,” he adds. The discovery came about from what Petigura describes as “an interesting twist of fate,” after Kepler experienced a hardware failure about a year ago. Previously, the telescope was intended to study one part of the sky for seven years, But after it malfunctioned, NASA created a new survey called K2. The new mission inspects more sky in a shorter period of time, which yields a greater discovery of nearby planets. Although Kepler has found over 4,000 planets, most of them have been about 1,000 light years away. In contrast, the planets in the recently discovered system “are only 100 light years away, so they’re 10 times closer than the typical star that Kepler found planets around in the original mission,” Petigura explains. Because the system is so close, it will be easy to continue to observe. Over the next few months, researchers will learn both the mass and size, which will allow them to calculate the density. This will help scientists determine if the planet is rocky like the Earth or gaseous like Neptune. Petigura is involved in the efforts to measure both the masses of the planets and what elements compose their atmospheres. “I think those two observations are going to bear directly on our understanding of how unique our own Earth is,” Petigura says. Soon, researchers will also be observing the planets with the Hubble Space Telescope. In his research, he has determined that 74% of Sun-like stars have at least one orbiting planet. To Petigura, the discovery of the new system proves that Kepler has the potential to reveal incredible findings.