Sunday, December 27, 2009

Hunting Alien Worlds

Q&A: Lowell Observatory astronomer Travis Barman was on the Keck telescope team that made the first direct observations of exoplanets.

In our Top 10 Space Stories of the Decade, the Discovery News #1 story was the direct imaging of planetary systems beyond our own. This endeavor was so profound as it not only opened up a new era for observing extrasolar planets, it ignited the imaginations of the public and scientists alike.

The simultaneous discovery of three alien worlds orbiting the star HR 8799 and a huge exoplanet orbiting the star Fomalhaut were made by the Keck telescope in Hawaii and the Hubble Space Telescope, respectively.

Travis Barman/Lowell Observatory
"He was blinking two images taken at different times. And we were both smiling.
He turned to me and said, 'don't tell anyone.'" -- Travis Barman
Travis Barman/Lowell Observatory

Travis Barman, a member of the Keck team, speaks with Steele Wotkyns, Lowell Observatory's Public Relations Manager, about this historic time in the Fall of 2008.

Steele Wotkyns: Describe your background. You're from rural Georgia. How did you get from there to here?

Travis Barman: My father was the reason we ended up in rural Georgia. He is a biologist and became a professor at Georgia College, a small school in central Georgia. My brother and I grew up in a very academic environment and my parents introduced me to science and computer-related science at a very early age.

I started college at Georgia College but soon transferred to the University of Georgia, double majoring in math and physics-astronomy. About the time I was considering grad school, they hired a new professor, Peter Hauschildt. He brought this huge code called Phoenix, a lot of grant money, and international collaborators. And, right when I was entering graduate school, the field was getting hot. In 1995 51 Pegasi was discovered -- the first "hot Jupiter." I was pretty lucky.

Steele: Describe some of your work. You collaborated on a team that got the very first direct images of planets outside the solar system, what was that like?

Travis: During my first post-doc position (Wichita State), I wrote my first successful grant proposal -- to NASA's Origins program. I decided to take the money to UCLA for my second post-doc where I got involved in the exoplanet direct imaging program. We have been looking for faint, co-moving companions around young stars.

The program is one where you have to have a lot of stamina. There are a lot of null results. You don't find anything... and that goes on for years and years.

But, in 2008 I was at Keck when my colleague Christian Marois was taking images of stars for our program. We always try to pump ourselves up -- this is going to be the one. The odds are really not good, though. So, anyway, on that run I came back late the next morning into the Keck control room. Christian had already done a preliminary reduction of one of the targets, HR 8799. He was blinking two images taken at different times -- the way we find these planets. And we were both smiling. He turned to me and said, "don't tell anyone."

We knew then we had one planet and there was a second one that was sort of visible in the data. It was exciting. But, our team had a lot of work to do. While Christian was cleaning up those images, a third planet was revealed. But we were cautious. And, we were lucky -- we had some more telescope time at Keck and could take more data. So, the story sort of built up: one planet, two planets, three planets -- over a few months. None of us could focus on other work. We just wanted to stare at that image of three planets.

Steele: Was the next biggest discovery for you the first detection of water vapor in the atmosphere of an extrasolar planet?

Travis: That was back in 2007. So I was looking for ideas -- I wanted to put in an archival proposal to look at existing exoplanet data. I was interested in HD 209458. But when I reviewed the literature I discovered what I wanted to do with the data had mostly been done. I was a little bummed but compared those other results to my models anyway. I was amazed at how good the agreement was -- particularly at the longer wavelengths where water absorption was present.

This was a nice, robust little result -- you'd have to work hard to explain the data any other way. Water is definitely there.

Steele: How would you describe the media interest in this discovery?

Travis: It was huge. The media sort of went nuts with it. They let their imaginations run wild, totally wild. I was very careful to say it was water vapor and not liquid water -- many did not make that distinction. It became this media storm. People were very excited by it for many reasons.

Steele: But you are a different kind of astronomer since you focus on the best possible models for how nature behaves and you also do observational astronomy?

Travis: Yes, there's an apparent divide between the two. Both sides approach problems in a different way. I am trying to avoid becoming someone who spends his entire life doing one thing one way. So, for example, taking observations of the three newly discovered extrasolar planets orbiting HR 8799 gives me this opportunity. It's like a working vacation from theory. Being at Lowell gives me a constant connection to observational astronomy.

Observational astronomy is interesting to me. It's similar to when you take something apart and put it back together again -- you learn how all the pieces go together. It gives me a strong appreciation of "real data." But I think one reason you don't see that many people doing both is the danger in being a jack of all trades and a master of none. It takes so much time to be an expert theorist or an expert observer. So, in my career I will always lean towards the one side -- modeling.

Steele: What are you working on now?

Travis: We're following HR 8799 up observationally and I'm taking the lead on one of the exoplanets. This work is exciting since we are getting the first look at planets different from hot Jupiters. These new planets orbit further out from their host star, placing them in a totally different environment than hot Jupiters -- and they are very young planets. They're fresh out of the oven compared to the known hot Jupiters.
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