With little fanfare, though, a few groups of determined researchers kept advancing toward the stars — albeit at an agonizing, incremental pace. Starting in the late 1980s, a collaboration between the U.S. Navy and the Lowell Observatory began developing the Navy Precision Optical Interferometer (NPOI) in Arizona. Around the same time, at Georgia State University’s Center for High Angular Resolution Astronomy (CHARA), astronomer Harold McAlister championed an interferometry machine combining the light from six separate telescopes on California’s Mount Wilson. After 16 years of planning and construction, CHARA finally began full operation in 2001. Soon after, John Monnier at the University of Michigan began work on an instrument called MIRC (Michigan InfraRed Combiner) that could convert the merged light to produce meaningful images. He tested it on the nearby star Altair in 2006, and found that he could clearly see how the star’s rapid rotation whips it up into a roughly egglike shape.
Roettenbacher read about the Altair results while she was in college at Ohio Wesleyan University. “I remember thinking, ‘This is the coolest thing ever.’ I was so fascinated that we could [clearly see] stars that aren’t the sun,” she says. At the time, she had no idea that she’d be doing such things herself. But just a few years later she was doing her graduate work at the University of Michigan, slaving away with Monnier to jam beams of light together and zeroing in on Zeta And as the perfect target for a stellar close-up.
The Stars are Ours
What Roettenbacher was attempting required a level of precision well beyond what had come before. With interferometry, there is no point-and-shoot. Getting a clear picture of a star would require a tremendous amount of additional, tedious work.
Zeta And takes 18 days to rotate, so Roettenbacher had to monitor the star for at least 18 nights, all night long. That was the easy part; then came the data processing. Optical interferometry at CHARA requires collecting the light beams from six different telescopes, sifting through multiple gigabytes of data, and then combining the beams to synthesize the kind of image that otherwise would be possible only with an enormous space telescope. Finally, all the processed data get imported into a software program, developed by Monnier, that translates the lightwave information into a picture.