Seniors' star study offers down-to-Earth lessons

  • Published
  • By Don Branum
  • Air Force Academy Public Affairs
U.S. AIR FORCE ACADEMY, Colo. --  A lot of college students spend late nights in dimly lit spaces searching for celestial bodies. However, for two Academy seniors, the celestial bodies in question are worlds the size of Jupiter that orbit stars hundreds of light-years away.

Cadets 1st Class Samantha Latch and Gordon Spahr spent their spring semester collecting information about an extra-solar planet known as Wasp-12b and presented their findings at the Colorado Springs Undergraduate Research Forum at Colorado College in April.

The seniors, from Cadet Squadrons 08 and 34, respectively, had two goals: First, they would try to determine why Wasp-12b's orbit appeared to be speeding up. Second, Latch said, they would see if they could provide good-quality observational data to the larger scientific community.

Wasp-12b is named after the Super Wide Angle Search for Planets organization, which discovered it April 1, 2008, according to the organization's website. Its parent star, Wasp-12, sits about 870 light-years away in the constellation Auriga, meaning that light traveling from the star takes 870 years to reach observers on Earth.

What astronomers have noted almost defies description. The planet, which is one and a half times more massive than Jupiter, orbits its star once every 26 hours. Because the planet lies so close to its parent star -- a mere 2.1 million miles -- midday temperatures top 4,000 degrees.

Another side effect of the planet's proximity is tidal forces from the star, which pull the planet into an egg-like shape and tear matter away from the planet at the rate of 193 quadrillion tons per year -- or about 175 Death Stars per year if Lehigh University students' math is correct.

A few characteristics make Wasp-12b an ideal candidate for observation. Its parent star lies in the constellation Auriga, which is far enough north that it's easily observable from Colorado. Its short orbital period gives cadets a chance to observe it for three days at a time every two weeks, Latch said, and more observation time means better data.

And then there was the matter of Wasp-12b's orbit: Already a breakneck 26 hours, it seemed to be getting even shorter, according to research published by Grace Maciejewski and others in 2010 and 2011.

"The variance in transit time usually indicates the presence of a third body in the system," said Latch, a native of Phelps, N.Y. "But Wasp-12b is supposed to be alone."

The Maciejewski paper didn't offer any explanation for the transit time variances, so Latch and Spahr put their own hypothesis together: The planet's orbit was speeding up because it was losing mass.

The cadets, who both began their freshman years in Cadet Squadron 23, burned a lot of midnight oil, staying up until 1 or 2 a.m. Dr. Devin Della-Rose, an associate professor with the Physics Department here, stayed up late with them, Latch said.

"He's really dedicated himself but geared toward letting us lead the charge," added Spahr, a native of Lafayette, Calif.

The data didn't lend itself to a "smoking gun," so the reasons behind Wasp-12b's decaying orbit remain a mystery, Latch said. But she and Spahr both felt good about the quality of their data.

"The error margin was ... out there on the same level as professional teams," Latch said. "Seeing that we're running with the pack was really encouraging because we know that when we contribute data, we're going to be listened to."

What's more impressive is that the cadets accomplished a good margin of error with a 50-year-old telescope, Della-Rose said.

"We're down to a 10-percent error in any of the magnitudes that we measure," he said. "One of the professors who used to teach here, Raymond Bloomer, came out a couple of years ago with two of his undergraduate students. Learning from him was really invaluable in helping us cut down our error bars."

The lessons they've learned can also benefit the Air Force in the future, Della-Rose said.

"Some people would say, 'We don't have an astronomy (Air Force specialty) in the Air Force ... so why are cadets doing this kind of work at the observatory?'" he said. "First, they're learning the scientific method, and that's universal. Second, the tools and techniques that they've used to study exoplanets are the same that officers on active duty use to study spacecraft, so the applications for space situational awareness ... the tactics and techniques are exactly the same."

Della-Rose added that the inconclusive result doesn't mean the research is done. For starters, the cadets presented their findings at CSURF. In addition, they will share their data with a group in Europe that's working on Wasp-12b, Della-Rose said.

"I'm going to continue my studies on Wasp-12 plus some of the other Wasp objects as well," he said. "So this is the start of things, really, not the conclusion."

Latch is slated to attend undergraduate pilot training at Sheppard AFB, Texas, after graduation, while Spahr will attend the Air Force Institute of Technology for post-graduate research.