Citizen scientists find planet with 4 suns
When Yale astronomer Megan Schwamb announced the discovery of a distant planet at an astronomy meeting in Reno this week, the stargazing world was left agog.
The oddball Neptune-sized gas giant she described was the first ever seen in a solar system of not one, not two, but four gravitationally connected stars. It was like the fictional planet Tatooine of “Star Wars” fame, but with two extra, distant suns. The planet orbits one pair of stars (which are rotating around each other), and in turn, another pair of stars orbits at a much greater distance.
Possibly the most unusual thing about the alien world was that it was discovered through an unlikely collaboration between two amateur astronomers working together over the Internet.
Kian Jek is a 53-year-old semiretired computer executive in Belmont, Calif., who fuels up with extra-large coffees and Pink Floyd. He searches for exoplanets — planets beyond our solar system — after he shuttles his sons to school in the morning.
His collaborator, Dr. Robert Gagliano, is a 68-year-old oncologist in Cottonwood, Ariz., who likes to work at an “ancient” computer in his bedroom that he “expects to crash any
day.”
Both men are participants in an online project called Planet Hunters, which allows them to sit at their computers and f lip through data from NASA’s Kepler Space Telescope.
Star by individual star, they and more than 170,000 other volunteers pore over graphs of changes in stellar light, looking for telltale dips in brightness that indicate a planet moving past its sun.
PH1 is the first confirmed exoplanet uncovered by the collaboration, which was launched in 2010 and is overseen by a team of professional astronomers, including Schwamb.
The volunteer Planet Hunters need not have any expertise in astronomy, cosmology or astrophysics. All participants have to do is answer simple questions about the data as they appear on-
‘If an old guy like me who is legally blind in one eye can detect [planet] transits, anyone can.’ — Dr. Robert Gagliano retired oncologist and Planet Hunter volunteer
screen. When they see the signature of dimming from a planet, they mark the spot with a box.
They can also discuss the search, and their observations of individual stars, in a chat area. That’s how Jek and Gagliano began working together.
It was Gagliano who first noticed a signal of a possible transiting planet while studying light curves — graphs that measure a star’s relative brightness over time — from the binary star pair known as KIC 4862625. The candidate planet appeared to transit twice, with an orbit lasting 137 days.
On March 2, he posted a message on the Planet Hunters talk forum to see what other people thought.
The next day, Jek, a regular on the forum who was also interested in the signals from binary stars, dug up additional light curves from KIC 4862625 by scouring publicly available Kepler data. He found a third transit that also corresponded with a 137-day orbit.
After making a few calculations to be sure he was on the right track, Jek noted his discovery on the Planet Hunters discussion thread. He also alerted Schwamb, who assembled a team of professional astronomers to study KIC 4862625 more closely using a variety of instruments, including the Keck telescopes on Mauna Kea in Hawaii.
Ultimately, the experts determined that what Gagliano and Jek had found was indeed a gaseous planet about 5,000 light-years away, with a radius about 6.2 times larger than Earth’s. They also realized, to their amazement, that the system actually had four suns, not two.
“They found this and handed it off to us, and we ran with it,” Schwamb said.
In general, scientists on the Kepler team use computer programs to sift through the millions of light curves the telescope collects.
But Schwamb said planets orbiting binary stars like KIC 4862625 may evade detection by those algorithms because changes in the light curves associated with the two stars’ rotation around one another might “drown out” the dim signal of a transiting planet.
On the other hand, Schwamb said, binary systems provide “a place where human eyes can do well.”
Jek doesn’t spend long days rummaging through light curves anymore — much of his time on Planet Hunters now is spent analyzing other people’s data.
He still uses a telescope to marvel at actual stars, but is finding himself increasingly drawn to the Kepler light curves, which he describes as “fascinating ” and “beautiful.”
“During a recent star party thrown by a local astronomy group, I realized it’s nice to be at home sitting on a couch, looking at a computer screen and not braving the cold,” he said. “Fortunately or unfortunately, I think in the future all astronomy might be done like this.”
Gagliano praised Planet Hunters for its collaborative nature and for opening up astronomy to the masses. He estimates that he has studied something like 82,000 light curves on the website, occasionally spending as much as 12 hours in a single weekend looking at his computer.
“If an old guy like me who is legally blind in one eye can detect transits, anyone can,” he said.
“For me this is the discovery of a lifetime,” he added. “I seriously doubt I’ll ever match anything like that again.”