Mason Student Reaches For Stars, Finds Galaxy

Article and Video by Connect Mason Reporter Edwin Mora. Images provided by Lisa Horne.

Junior Lisa Horne recently found her name placed in the astronomy history books when she discovered a new galaxy. Horne found the spiral galaxy, AGC 310842, on just her second day of work at Cornell University in Ithaca, New York this past summer, as part of an undergraduate apprenticeship program here at Mason.

An astronomy major, Horne was selected to go with Mason's own assistant professor Jessica Rosenberg to Cornell to join the Arecibo Legacy Fast ALFA (ALFALFA) survey team, which aims to find and map 25,000 galaxies in nearly one sixth of the sky as far as 800 million light years away using the ALFA instrument, according to their website.

Sifting through images gathered by the world's largest radio telescope, Horne's role was to find anything that stood out.

“My job was to clean up the data and point out anything unusual,” said Horne.

She made the discovery Aug. 19 while observing her first set of data.

“I knew it was something odd, but I didn’t know exactly what it was,” Horne said, noting that the data resembled white noise on the screen. She said that initially a set of data took her about four hours to go through. However, with more practice, she took less time to go through the data. She also had to accept the risk of a satellite getting in the way of the telescope and destroying all her data.

After her discovery, it was determined by the research group that the odd hydrogen spectral lines were indeed a galaxy. The instrument that Horne used to find the galaxy uses a different approach than the usual optical search to look for galaxies.

“Often when we look for galaxies other than our own, we look for stars,” said Rosenberg. “In this project, we’re looking for gas regions.” According to Rosenberg, the new galaxy is about 500,000 million light years away.

Cornell Astronomy Professor Riccardo Giovanelli explained in a press release that the ALFA, or Arecibo L-Band Feed Array, is a seven-pixel camera that takes sensitive radio images of spectral lines emitted by hydrogen, the most abundant element in the sky. The instrument was added to Arecibo, the world’s largest single-dished radio telescope, in Puerto Rico.

Along with other research grants, this project is supported by the National Astronomy and Ionosphere Center at Cornell. The undergraduate ALFALFA team is made up of 14 institutions, including Mason, in a program to promote undergraduate research within the ALFALFA project.

Rosenberg said that the grant makes it possible for undergraduates to be a part of this research. “The grant tries to get undergraduates involved in research to prepare them for their astronomy career,” said Rosenberg. “It facilitates the opportunity to find galaxies.”