University of Minnesota
School of Physics & Astronomy

Spotlight

Looking for Exoplanets

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A research team at the University of Minnesota has been using the power of the Large Binocular Telescope (LBT) in Arizona to search for planets outside our solar system in hopes of answering some questions about the evolution of our own.

Professor Chick Woodward and his group are part of a 150 night program, observing nearby stellar systems. The group focus is to characterized the physical (mass, radius, etc.) and atmospheric properties of exoplanets –planets outside our solar system--and examine the architecture of planetary systems to determine how stable they are. “In our solar system, we have had stable orbits for four billion years which is enough time for interesting things to happen.” Woodward and his collaborators want to know how common such stable orbits are in nearby galactic systems, and understand the distribution of exoplanet system masses and sizes. If life were to develop outside our solar system, it might require orbits that are stable for several tens of millions of years for exoplanets of a certain mass, size, and atmospheric composition. Helping to identify which exoplanet systems have stable architecture similar to our own planetary system, could help astronomers identify potential exoplanets that could develop life.

Woodward says the LBT has a unique capability in the world of astronomy. It is equipped with a state of the art inferometer (an instrument which can combine the light from the two 8.4-m diameter primaries into an effective aperture size of over 22.3-m) and a secondary mirror, which corrects for atmospheric distortion. “We don’t want atmosphere to blur the starlight,” he says, “in our game, the twinkle-twinkle of little stars does not permit us to get sharp pictures of the sky from the ground.” Telescopes with sophisticated adaptive optics systems can freeze the “twinkling” and enable very sharp imagery. “In combination with large primaries on the LBT we can get better image resolution than Hubble, which opens up space to study all kinds of phenomenon. “With these tools Woodward can study the birth of solar systems.

“We also look at the end point, the death of stars, by studying novae and super novae. These events are also the source of many of the interesting elements in the Universe, such as carbon, magnesium, oxygen and even gold. All of these observations help astronomers to continually piece together a picture of how our solar system evolved, while looking for life in others.”

Another part of Woodward’s research is an ongoing characterization of small bodies that come within a certain distance of the Earth. Woodward relates that Congress by public law has charged astronomers with finding and characterizing these bodies as part of planetary protection efforts. “We find things that could go bump in the night. You can thank disaster films like Armageddon or Deep Impact if you like.” Woodward said. “The ultimate goal is to keep tabs on a million or so bodies as small as 1 km in size, on the off-hand chance of a close-encounter, which could result in a collision.” Other reasons to study the small bodies are that asteroids could also be a stepping-stone to visiting Mars and the commercial potential of asteroids for mining. “Our job is to look at populations, find out how they arose, find out how they might possibly bring the active ingredients for life to host planets.” Woodward compares the small body studies to space archeology. “We study the left over stuff from formation of solar system and we can take that knowledge and extrapolate to exoplanets as well.”