Far-off worlds will not seem as mysterious as they once were because of two Ohio State graduate students.
Astronomy graduate students Chris Burke and Joshua Pepper are working on research projects that should uncover new planets outside of the solar system.
“There’s people who say there are no planets around any other stars, and then there’s people who think every star has a planet. So you can think that, but it may not be the truth. So we are actually trying to quantify the truth to put numbers to these important questions for the first time,” said Burke, a fifth-year graduate student working on his doctorate.
Burke and Pepper are using the same method to look for planets but with different approaches.
“We’re looking at different types of stars. [Pepper] is looking in the field at bright, nearby stars that are all around us in every direction. My project is looking at open clusters,” Burke said.
Open clusters are a clump of stars in the sky that are about half the size of a full moon. All of the stars in the open cluster were born at the same time and have the same chemical compositions. Burke said they resemble a control group of stars.
The technique the graduate students are using to find planets is called the transit method.
“It’s like an eclipse because when these planets cross in front of a star, it dims the light of the star. The star doesn’t seem as bright,” Burke said. “So we measure the brightness of the stars.”
An image is taken every two to five minutes, but the eclipse lasts several hours. The brightness of the star is graphed as a function of time. The graph shows the star getting fainter, before returning to its normal brightness, which is when the planet is crossing the star.
A key difference between the two graduates’ research approaches is that Pepper is using a much smaller telescope.
“What we found out was that if you are going to go ahead and observe these things based on the brightness of these stars, it doesn’t actually matter what size your telescope is. And then we did some further analysis, and we found out that you can actually theoretically discover these planets using a very small telescope,” said Pepper, a third-year graduate student also working on his doctorate.
Pepper said the kind of research he is doing is accessible to graduate students. It does not require a huge capital investment or an enormous telescope.
“You can actually just do it with some smart planning and a small telescope, so it’s cool,” Pepper said.
Burke said he and Pepper can determine whether the planet being discovered is one with the mass of Jupiter or the mass of a hundred Jupiters.
“With this technique, at least from the ground, we are not going to be able to find Earth-sized planets. We are going to be limited to objects that have radii that are around Jupiter’s size and larger,” Burke said.
Their research will also aid in answering questions about the chances of life existing on other planetary bodies.
“It also helps people place limits on the likelihood of life in the universe because you have to estimate how many stars have planets around them, and so these type of numbers that we are starting to figure out will place directly on getting a better handle on whether or not there could be other intelligent life or just other types of life out there,” Burke said.
Using the transit method to discover planets is also employed by institutions such as Harvard University, the University of California at Berkeley and the University of California at Santa Cruz.
Astronomy professor Rick Pogge, adviser to Burke and Pepper, said researchers at OSU can work off each other’s strengths.
“We have a strong interaction between the people who build instruments, observe and theorize,” he said.
