Students Attending VLA

Kaitlin Haugland '08
Korey Haynes '09
Hans Most '10
Jillian Scudder '09
Jacob Weindling '10

Macalester Astronomy Students And A Galaxy
Far, Far Away

Earlier this spring, a group of Macalester astronomy students had the opportunity to spend time at the Very Large Array (VLA), one of the premier astronomical observatories in the world.

The VLA consists of 27 radio antennas in a Y-shaped configuration on the Plains of San Agustin, fifty miles west of Socorro, New Mexico. Each antenna is 25 meters (82 feet) in diameter. The data from the antennas is combined electronically to give the resolution of an antenna up to 36 km (22 miles) across, with the sensitivity of a dish 130 meters (422 feet) in diameter.

The VLA makes time available to college-level classes that discuss observational and radio astronomy. The Macalester group, that included students enrolled in PHYS 440 (“Observational Astronomy”) and Professor John Cannon, took advantage of this opportunity to observe the Orion dwarf galaxy.  Located in the familiar winter constellation of Orion the Hunter, this galaxy is roughly 13 million light years away. While this is an enormous distance, it is right in our backyard in an astronomical sense.  The galaxy’s relative proximity, and its large content of neutral Hydrogen gas, allowed the spectral line observations performed by the Macalester students to reveal the detailed structure of the galaxy for the first time. Using the data, the group is studying the distribution of visible and dark matter in the galaxy, and probing the interaction between star formation and the interstellar medium.

"I thought the VLA trip was an amazing experience," said Korey Haynes '09. "I never dreamed that I would get to go to a national observatory as an undergraduate. It’s the kind of thing I thought I’d be lucky to do as a grad student, or even as a professional astronomer, and here I’ve done it as an undergrad."

"It was one of those trips where everything just meshed; all of us were having a ball," said Jillian Scudder '09. "We were all motivated to get as much work done as possible, and we were going to do it well. It helped that we were all on a science-high from being at the VLA. That sense of being at the VLA pervaded the whole trip, culminating with the chance to walk around inside the dish of one of the antennae in a high breeze."

The students in PHYS 440 are all physics majors with an astronomy emphasis.  By the nature of the discipline, astronomers are observers; we use various observing tools to gather information about celestial objects.  What we seek is a broad understanding of the constituents of our universe; the information we receive from any given object depends on how we look at it.  These students have made extensive use of the Macalester Observatory here on campus to acquire optical images of stars, clusters and galaxies.

By using telescopes that operate at radio frequencies, different types of information can be obtained.  The VLA receives signals that are in many ways similar to the radio waves a car radio receives.  Researchers don’t “listen” to these signals, but rather use them to create images of the neutral Hydrogen in galaxies: the material between the stars.  Since stars form from this gaseous component, by observing it, researchers can piece together the puzzle of how stars (like our Sun) came into being.  The VLA allows them to study both the location and the motion of the gas in a nearby galaxy; and they can therefore discern how it rotates, how much mass it contains, and many other important characteristics.