Physics and astronomy major Erik Alfvin ’15 (Shorewood, Wis.) is celebrating the discovery of a new galaxy announced in a paper he co-authored with Macalester astronomy professor John Cannon and other investigators.

The Astrophysical Journal Letters, which published the paper in its May 20 edition, is a journal for the rapid release of high-impact results that are deemed worthy of swift dissemination to the scientific community. At Macalester, where the student-faculty ratio is 10:1, it is possible for an undergraduate to be involved in a unique discovery such as this.

Working with Cannon in summer 2013, Alfvin used data from the Very Large Array (VLA) radio telescope in New Mexico to create three-dimensional images of the neutral hydrogen in nearby galaxies. The goal was to determine the nature of curious objects called “H-alpha dots”—regions where new stars are being born, but apparently located outside of the nearest normal galaxy. “The goal was to see if there were any signs of a hydrogen bridge between the star-forming regions (the H-alpha dots) and a parent galaxy,” says Alfvin.

This spring, Alfvin continued on a related project that culminated in the Astrophysical Journal Letters article. The mystery they were investigating had to do with why the relatively massive galaxy DDO 68 contained so little gas enriched with heavy elements (“metals”), when most galaxies this massive are more metal-rich. One possible answer is that metal-poor material was coming from another source.

“We discovered a previously unknown companion galaxy to DDO 68, as well as a bridge of hydrogen gas that connects the two,” says Cannon. “The two galaxies are interacting at the present time; this supports the interpretation of metal-poor gas falling into DDO 68.”

The process of scientific discovery has left a lasting impression on Alfvin:  “My ‘ah ha’ moment was when I saw the first galaxy image that I made from scratch. It reminded me why I got into the field in the first place and why this stuff was so exciting—I did something that real astrophysicists do.”

In addition to being published as an undergraduate, there is a personal satisfaction for Alfvin: “It feels good to know how the largest things imaginable operate.”

May 6, 2014

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