Indiana University Research & Creative Activity

Space

Volume XXVII Number 1
Fall 2004

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rainy night at observatory
Astronomers Kent Honeycutt and Stella Kafka check the rainy night skies at the Kitt Peak National Observatory in Arizona.
Photo by Josh Schachter

Kent Honeycutt
Kent Honeycutt works on reports in an observatory office.
Photo by Josh Schachter

Stella Kafka
Stella Kafka manages an array of computers in the observatory's control room.
Photo by Josh Schachter

Spying on the Stars

by Kimi Eisele

Stella Kafka is a little bit grumpy. It's raining and chilly, and thick clouds hide the skies above Kitt Peak, a mountain observatory in the Sonoran Desert of southern Arizona. Kafka, a graduate student in the Indiana University Bloomington Department of Astronomy, has come here specifically to study stars. But because of the rain, the telescopes are closed down for the night.

You travel so far to work at the facility, and then this happens. "I have an allergic reaction to clouds," Kafka says.

Kafka's adviser, Kent Honeycutt, the John Hill Professor of astronomy at IUB, just shrugs. He's spent much of his career visiting the mountain, which on clear nights (the norm in this desert) offers some of the greatest views of sky anywhere in the world.

Just 56 miles southwest of Tucson, Ariz., Kitt Peak is home to the world's largest collection of optical telescopes. One of them is why Honeycutt and Kafka are here.

It's a 3.5-meter, $14 million telescope, the newest and second-largest telescope on Kitt Peak, jointly owned and operated by the University of Wisconsin, Indiana University, Yale University, and the National Optical Astronomy Observatory, a research center funded by the National Science Foundation. Called WIYN, this consortium of public and private universities and a national research center was the first of its kind. Researchers from IU are allotted a 17 percent "share" in the facility.

Because scientists have to apply for and reserve time at the facility, bad weather means less time with the telescopes. "I prefer to do my science than to sit at the dome and wait for the snow and rain to stop," Kafka says.

Fortunately, Kafka and Honeycutt have already had a week of on-site work here, which is essential for their research. They are trying to understand phenomena called accretion discs. Accretion discs are formed in a binary star system when one object, such as an M dwarf star, transfers gas towards a smaller, more compact star such as a white dwarf. Gas flows from the larger star to the smaller star, forming a disc-like ring around the white dwarf. Such stellar objects are often bright, although they "shine not by the stars themselves but by the luminous discs," Honeycutt explains. "Images of them show what appears to be just a star, but spectroscopy reveals that the light is actually coming from these strange objects we call accretion disks," he says.

Accretion discs are often unstable and undergo outbursts, Honeycutt says. The binary systems containing accretion disks can lead to supernova, some of the brightest explosions in the universe. The WIYN telescope brings the scientists closer, literally and figuratively, to understanding them.

Both Kafka and Honeycutt have slept until early afternoon. Late nights of work mean astronomers lead nocturnal lives while doing research at the telescopes. On their last night at WIYN and on Kitt Peak, they thought they'd be taking data all night. Typically, they prepare their research for several hours, eat an early dinner, then pack a "night lunch" from the cafeteria. With the help of trained technicians and telescope operators, they open up the telescopes.

The WIYN telescope itself looks nothing like what most of us think of when we imagine a telescope. No long thin scope, no eye piece. Instead, the size of a small cottage, WIYN looks something like a spaceship with gauges, control panels, wires, angled posts, and a giant mirror.

Despite its size, the telescope is extremely precise. Mirror supports, thermal controls, and active ventilation of the telescope mount help protect it from the elements while allowing it to produce extremely high-quality images. On the backside of the mirror is a complex circular wall of actuators—small cylindrical instruments that push or pull on its back face to maintain a high-quality image. "It's a miracle of engineering," Kafka says.

The dome the WIYN telescope sits in is like a large, round, rotating garage with doors that slide upward and a large slit on the roof that opens up to the sky. The top half of the building itself can rotate 360 degrees, allowing the telescope to track the stars. Although the doors are closed tonight, the telescope operator rotates the tower to illustrate its path.

As the dome creaks and turns, Kafka gets giddy. She's beginning to come out of her bad mood. "This whole instrument is dedicated to spying on the stars," she exclaims. "This is our pride!"

WIYN's modern instrumentation means scientists can do many things with it. One of its primary instruments is an elaborate spectrograph that can acquire data from many stars at a time.

"Do you remember the Hydra from Greek mythology?" Kafka asks. "Think Hercules. The nine-headed snake!"

In the myth, Hercules beheads the snakes to regain his honor. Here, the Hydra helps astronomers understand distant stars and the binary systems that include accretion discs.

Instead of nine snakes, the Hydra instrument is made up of 90 fiber optic cables, each positioned at the object in the sky to be observed. "Normally you can only look at one star at time. This lets us look at 90 at the same time," Kafka explains.

The telescope is also equipped with imaging cameras called the Mini-Mosaic and the Tip-Tilt. The Tip-Tilt compensates for turbulence to record the sky more clearly.

When the slit and doors are open, Honeycutt says, you can see thousands of stars with just the naked eye. "Sometimes we come up here just to sit and be with (the telescope), to observe the sky. It's a pretty special place."

Still, most of Honeycutt's and Kafka's work occurs in the control room below. Kafka sits down at a computer monitor to review spectroscopic data. She pulls up an image that looks much like an EKG reading; essentially, it allows her to read the fingerprint of a star.

This kind of spectroscopy measures light from stars through the fibers and records the image onto a CCD, a charged coupled device, the same kind of imaging device used in digital cameras. The reading reveals the stellar structure, how hot it is, the chemical composition, and, of particular interest to Kafka on this trip, whether the star has starspots.

"We know the sun has activity cycles in which flares and sunspots come and go. This activity is seen in others stars as well, especially in small stars such as M dwarfs," Kafka explains. The imaging instruments allow Kafka and Honeycutt to monitor stars' brightness and how they change due to starspots and other effects.

With the Hydra spectrograph, Kafka is able to analyze the light of stars in the same star cluster—stars of the same age, initial chemical composition, and distance from the Earth. By studying spectra of the stars of the cluster, Kafka can also learn their level of starspot activity. Understanding the nature of this activity in single stars might help her understand magnetic activity in a binary system, which could help explain accretion disk phenomena.

Understanding how magnetic fields of secondary stars within binary systems contribute to the formation of accretion discs may tell us something about our own solar system's origins, Honeycutt says. "These (binary) systems are likely progenitors of supernova. One theory about our solar system is that its formation was initiated by a nearby exploding supernova, which may have been caused by similar binaries and accretion discs."

Of course, much of their research, the astronomers point out, happens away from telescopes. Back in Indiana, for example, Kafka creates files to position the Hydra's microfibers with the coordinates of the stars. And sometimes Kafka and Honeycutt use the WIYN telescope remotely from Indiana.

Still, observing on site is preferable. "It's a complicated instrument," Honeycutt says of the telescope. "You're better off being here to make real-time decisions. You have more control."

Also, bringing students to the telescope can be particularly rewarding. At her advanced level, working with Kafka is equivalent to working with a colleague, Honeycutt says.

It's likely her enthusiasm for the science and its instruments helps as well.

"It's really exciting from the time you open up the telescope, doing the observations, to the minute you see your final results on the screen. You're looking at something unique. We've discovered things we didn't even know existed," Kafka says.

Such discoveries are what make their work exciting, the astronomers say. "You think you understand something, and you go back a year later and find something completely different," says Honeycutt.

Aside from getting to spend time with the skies, Kafka says, the greatest reward is getting results. Two years ago, as she was monitoring with Hydra, she discovered an expanding wind around an object. It was totally unexpected. "When I first saw it I thought there was something wrong with the data reduction," she says. "Then I went back and realized, it's there, really."

Honeycutt agrees. "Finding out something, some aspect of the universe that no one else knows, at least for a few days, then sharing that discovery with others, can be pretty exciting."

Born and raised in Greece, Kafka says by studying astronomy, she is making contributions to scientific discoveries reaching back to ancient civilizations in Babylonia, Mesopotamia, Greece, and Egypt.

But with due respect for his student, Honeycutt says, "Aristotle had it wrong when he said the skies were immutable and unchangeable. The skies are dynamic."

Kafka tilts her head back, laughing. "It's so true."

Kimi Eisele is a freelance writer in Tucson, Ariz.

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