Extragalactic Wizardry


CATEGORY: Academics
TYPE: Articles
RELATED PROGRAMS: Physics & Astronomy

In Long Beach, Calif., at the 221st meeting of the American Astronomical Society, five undergraduate students received the prestigious Chambliss Astronomy Achievement Student Award. Two of the five are Macalester students: Melissa Marshall ’14 (Palos Verdes, Calif.) and Stephen Pardy ’13 (Yarmouth, Maine). Both are physics majors with an astronomy emphasis. Marshall is also majoring in computer science, which she used to enhance her research.

 Stephen Pardy ’13 with his poster

Stephen Pardy ’13 with his poster.

“I won the Chambliss Award for creating a software package called FITGALAXY that automates a series of time-consuming processes for analyzing extended sources like galaxies in astronomical images,” says Marshall. Her research was part of the SHIELD project, headed by astronomy professor John Cannon, who hired Marshall as part of his summer research team at Macalester.

“My task was to determine the stellar mass of these galaxies from infrared Spitzer Space Telescope images,” says Marshall. “Knowing the stellar mass of a galaxy is important in understanding the composition of a galaxy —the amount of gas, stars, dust, etc., and the amount of baryonic matter compared to the amount of dark matter. These galaxies are relatively understudied because they are so physically small, low-mass, and therefore faint. FITGALAXY automatically selects an aperture, masks bright contaminating objects, and measures the brightness of the object.

“It was great to know that other astronomers thought my research was useful and an important contribution.”

“Macalester students—nine this year—have been regular presenters of their research results at American Astronomical Society meetings, but the Chambliss Awards made this year’s meeting especially exciting,” says Cannon. “There are thousands of attendees at these conferences, and many hundreds of presentations.”  

Stephen Pardy also conducted research with Professor Cannon. In summer 2011, they used data acquired with West Virginia’s National Radio Astronomy Observatory’s Green Bank Telescope (the world’s largest moving structure on land) to quantify the amounts of neutral hydrogen in a sample of nearby galaxies. This past summer he was selected for a very competitive REU (Research Experience for Undergraduates) program at the National Radio Astronomy Observatory in Charlottesville, Va. As a senior, he has continued working closely with his REU advisor and they plan to publish their findings soon.

 “We were testing a new method of studying the interstellar medium—gas that is the primary component of most galaxies,” says Pardy, who learned a lot about data analysis and algorithms, as well as astronomy. “This gas is usually thought of as being found in clouds, which eventually collapse and form stars. This newer technique we used makes use of tree diagrams to show how regions of gas merge together. We applied this to a very high-resolution dataset from the beautiful Whirlpool Galaxy. Our research is leading us to new ways of classifying molecular gas regions and to interesting results about the molecular gas properties in other galaxies.”

Both Pardy and Marshall intend to continue their studies in graduate school. “That Melissa and Stephen were each selected for a Chambliss Award is a wonderful testament to the quality of research that they both have done,” says Cannon, “and to their promise as researchers for the future.”

PUBLISHED: 01/30/2013