Act One. 12.8 billion years ago, in the constellation Pisces: A massive star explodes. Light rushes out across the universe. (Curtain down.)
Act Two. Summer 2004, Chapel Hill: Astronomer Daniel Reichart imagines using the new SOAR telescope to see very distant, and therefore very old, events. Maybe, he predicts, he’ll use SOAR to witness the most distant explosion in the universe.
Act Three. Fall 2005, Chapel Hill and Chile: Remnants of Act One’s explosion become visible from Earth. Reichart sees the light.
Okay, so it needs a little tweaking before it hits Broadway, but the fact is that Daniel Reichart and a cast of Carolina students have measured the distance to the oldest and most distant astronomical explosion to date: a gamma-ray burst likely caused by the death of a star at least thirty times more massive than our sun. NASA’s Swift satellite detected the burst on September 4, 2005, and within three hours, Reichart was using SOAR’s OSIRIS infrared instrument to view the burst’s afterglow and calculate the distance to the explosion.
Light from that explosion, it turns out, had to travel 12.8 billion light years to get to us. Most astronomers think the universe is about 13.7 billion years old. That means the burst came from near the edge of the visible universe, and it happened when the universe was a mere toddler—only about nine hundred million years old.
“This is uncharted territory,” Reichart says. “This burst smashes the old distance record by five hundred million light years. We are finally starting to see the remnants of some of the oldest objects in the universe.”
The SOAR telescope is in the Chilean Andes. Workers there happened to install the telescope’s OSIRIS infrared instrument a few days before the Swift satellite detected the burst. So Reichart told one of his undergraduates, Josh Haislip, to bone up on the OSIRIS instrument just in case something interesting happened.
And boom. When the Swift satellite detected the burst, it notified Haislip and Reichart on their cell phones, and they headed to the remote observing center, here in Chapel Hill, to take control of the SOAR telescope. Now Haislip will be first author—play the starring role, that is—on the resulting scientific publication.
“The earliest stars exploded eons ago; we know very little about them,” Haislip says. “One of the best ways we can study them is by watching for their explosions. Swift can pinpoint the locations of the explosions, and telescopes such as SOAR can study the composition of the debris to understand where and when these stars formed and what they were made of.”
Reichart is an assistant professor of physics and astronomy. Other students who worked on the burst are seniors Chelsea MacLeod and Justin Kirschbrown and graduate student Melissa Nysewander. The Southern Astrophysical Research (SOAR) telescope is a public-private partnership among UNC-Chapel Hill, the U.S. National Optical Astronomy Observatory, the Ministry of Science of Brazil, and Michigan State University.