Binary Asteroid
January 7, 2014

College Students Discover Rare Binary Asteroid

[ Watch the Video: Binary Asteroid System Discovered ]

Brett Smith for - Your Universe Online

An undergraduate astronomy class for non-astronomy majors at the University of Maryland has made a rare discovery that was completely overlooked by professional scientists: a pair of asteroids that orbit and regularly eclipse each other located in the main asteroid belt between Mars and Jupiter.

There are currently fewer than 100 known eclipsing binary asteroids and the student’s discovery will be presented on Tuesday at the 223rd meeting of the American Astronomical Society in National Harbor, Md.

"Actually contributing to the scientific community and seeing established scientists getting legitimately excited about our findings is a very good feeling," said Terence Basile, a cell biology major at from Beltsville, Md.

"This is a fantastic discovery," said Drake Deming, a University of Maryland astronomer who was not involved with the class. "It provides an unprecedented opportunity to learn about the physical properties and orbital evolution of these objects."

The dual asteroids, collectively known as 3905 Doppler, are just one object from hundreds of thousands in our solar system's main asteroid belt between Mars and Jupiter. The object was first discovered in 1984, but given little thought over the following decades. In September 2013, students in Dr. Melissa Hayes-Gehrke’s astronomy class picked it and two other asteroids to observe because they were easy to see in the autumn sky and somewhat mysterious.

Over the course of four nights in October, four-person student teams tracked and photographed the asteroids with a privately-owned telescope in Nerpio, Spain, which was controlled remotely over the Internet. The main goal of the assignment was to capture changes in the brightness of each asteroid's reflected light.

These images were then used to create a light curve, or graph of an object's light intensity over time. Changes in brightness are often the result of the object's shape, with asymmetrical objects having a range of brightness and symmetrical objects producing a constant intensity. After finding the time between maximum light intensities, scientists can determine how fast an asymmetrical object is rotating.

When the two teams studying 3905 Doppler created its lightcurve, they discovered that the asteroid's light sometimes faded to nearly nothing.

"It was incredibly frustrating," said Alec Bartek, a physics major from Brookeville, Md. "For some reason our lightcurve didn't look right."

Hayes-Gehrke suspected that 3905 Doppler was actually two asteroids orbiting one another, with one of the two asteroids occasionally blocking the light of the other.

Lorenzo Franco, an amateur astronomer in Italy, was viewing 3905 Doppler at around the same time and his data was able to confirm that the light curve came from a binary asteroid.

"Even then I was not fully aware of how special the discovery was," said Brady Bent, an economics major from Arbutus, Md. "I thought it just meant we would have to do more work. As we continued to analyze our data, other professors in the Astronomy Department came over to view our work. At this point I understood just how rare our find was."

Hayes-Gehrke noted that the students used the same problem-solving methods that a professional astronomer would use to analyze an unanticipated result.

"That's the whole point of the class," Hayes-Gehrke said. "I'm hoping they'll keep in mind, when they read about scientific results, that it's not a cut-and-dried process, but the scientist probably had to go through some kind of struggle to get results."