A PROJECT OF ASTRONOMICAL PROPORTIONS

A team of Ohio State astronomers has been awarded a $5 million dollar contract from KASI (Korea Astronomy and Space Sciences Institute) to build three 340 megapixel cameras—three of the largest ever made-- for the Korea Microlensing Telescope Network (KMTN).

Andrew Gould, Thomas Jefferson Professor for Discovery and Space Exploration; Bruce Atwood, project scientist; and Tom O’Brien, project engineer, successfully competed for the grant. With Scott Gaudi, associate professor of astronomy, they form the team of Ohio State scientists and engineers, who will build the cameras.

Ohio State’s team had an edge: Gould is internationally-known as a pioneer of the technique of gravitational microlensing and has trained and mentored many of its top planet-hunters, including Gaudi. That combined with a long-standing, well-supported engineering team, gives the Department of Astronomy a range of expertise few others can match.

“The fact is that a project of this scope could not have been built within budget and time-frame without the expertise, experience, and initiative of Ohio State’s Imaging Sciences Laboratory,” said Gould.

“Basically we provide one-stop shopping,” Tom O’Brien, project engineer said. “It is very rare for an astronomy department to have a dedicated in-house team of engineers.”

“This is a true collaboration among institutions and industrial partners worldwide,” Bruce Atwood, the project scientist, who has worked on several other such projects, said.

Two other partners will build the 1.6 meter telescopes and associated observatory buildings at three KMTNet observatory locations: Cerro Tololo Inter-American Observatory (CTIO), La Serena, Chile; South Africa Astronomical Observatory (SAOO), Sutherland, SA; and Siding Spring Observatory (SSO), Coonabarabran, Australia.

All teams already have begun work on the project and the clock is ticking. The first telescope will be installed at CTIO in Chile in April 2013 and Ohio State’s camera will be mounted in October 2013. The South African facility will become operational in March 2014 and Australia’s facility in June 2014.

Ohio State’s team will be collaborating with Korean scientists Chengho Han of Chungbuk University, who received his PhD from Ohio State, advised by Gould; Dr. Chung-Uk Lee (project manager) and Dr. Seung-Lee Kim (principal Investigator) of the Korea Astronomical & Space Science Institute (KASI).

THROUGH THE GLASS: The Importance of a Microlensing Network

Throughout history, humans have wondered: are there planetary systems around other stars, and do these systems resemble our own? For that answer, astronomers say they must probe beyond our solar systems for planets as small as the Earth or even smaller -- something that is very difficult to do from the ground using most methods.

The use of gravitional microlensing seems to be our best hope of finding very small planets, and is one of only proven techniques for finding them in the outer regions of planetary systems.

"Although only 13 planets have been detected to date using microlensing, these have provided invaluable insights into the processes at work in planet formation,” Gould said.

The disproportionate amount of information gathered from a small sample of planets is due to the nature of the microlensing technique, Gould explained, which is sensitive to planets on regions of parameter space that are inaccessible to the more traditional and heretofore more successful, planet detection methods.

“Microlensing is the hardest technique for finding planets,” Gould said. “You need lots of people to intensively monitor large parts of the sky, because what you see is very fleeting and will not be reproduced. So you have to be very aggressive in getting data when it happens—and then interpretation is not always obvious. You need huge computer networks, new algorithms, and dozens of people working together, since you need to be able to trace lots of points--one team to find events; the other to look at them. And you have to have networks of telescopes around the world with eyes on the sky 24/7.

“The advantage of microlensing is that it gives you the ability to detect planets in a way that is completely different than other techniques. All others are relying on light from either the planet or its host star, restricting you to stars that you can see, and that’s it.”

Microlensing, the astronomers say, is most sensitive to planets in the cold, outer regions of planetary systems. In our solar system, this region is occupied by the giant planets, and it is thought that this region is likely to be the ultimate source of water for habitable planets.

Microlensing does not detect planets or light—everything is coming from a background star, which observers can see get brighter. It’s sensitive to types of stars in the galaxy that are low mass, without lots of light, and it can detect free-floating planets in the middle of nowhere, which Gould believes is an extremely important clue to formation of planetary systems.

“While microlensing planet searches have likely saturated their planet detection rate in their current form, they have far from saturated their potential,” Scott Gaudi, a noted planet-hunter who has racked up considerable microlensing hours and detected some exoplanets in the process, said.

“Realizing this potential; however, will require a fundamentally new, next-generation approach to ground-based searches,” Gould explained. “KMT is the critical and central component of this next-generation approach.”

BIGGER/BETTER/FARTHER

Astronomers around the world are pinning their hopes on KMT. This planned system of three 1.6 meter wide-field telescopes will allow observers to discover and monitor thousands of gravitational microlensing events per year by observing dense star fields near the Galactic bulge.

Three identical telescopes and cameras will be constructed and deployed in sites in South America, South Africa, and Australia providing 24 hour monitoring of these microlensing events, weather permitting.

Detailed simulations indicate that such a next generational network enabled by KMT will increase the planet detection rate by an order of magnitude and measure the frequency of cool Earth-mass planets orbiting stars throughout the Galaxy.