Betelgeuse: Ticking Time Bomb?

Mansur Ghani
By Mansur Ghani May 12, 2011 18:22

The remnants of SN 1604, the last supernova to be seen in our galaxy. Supernovae enrich the interstellar medium with heavy elements. Photo Courtesy of NASA/ESA/JHU/R. Sankrit & W. Blair

It seems like the headline of the century: “Stellar Explosion will give Earth Two Suns by 2012.” Suddenly, all the 2012 doomsday prophecies seem to fall in place. Well, not quite. While scientists do believe Betelgeuse, a star located in the Orion constellation, is a likely candidate to be of one of the next stars to go supernova in our galaxy, some of the recent hype surrounding the event has clearly lost sight of the facts.

Betelgeuse is a red supergiant star approximately 10 million years old and in the last stages of its life. As the star approaches death, the core will no longer be able to undergo nuclear fusion. With no force to support its own weight, the star will collapse in a catastrophic event that will release more energy in an instant than our Sun will produce in its entire lifetime. Indeed, it is possible that the star has already exploded, but the light has not reached us yet since Betelgeuse is located about 430 light-years from Earth.

Perhaps due to a combination of sensationalist scientific journalism and the recent awareness in popular culture about 2012, reports have exploded on the Internet ranging in absurdity from claims that Betelgeuse will outshine the sun to warnings that it threatens life on Earth. Michael Faison, director of the Leitner Family Observatory at Yale, likened the hype around the supernova to the recent panic over Zodiac changes. “You never know what people are going to latch onto,” he said. The change in orientation of Earth’s rotational axis, which causes the Sun’s position relative to the Zodiac to change over time, has been known since at least 120 BC. But sometimes, poor journalism or misrepresentation of the facts can cause long-established astronomical trends to be mistaken for life-changing events.

Betelgeuse has a visibly reddish tint and is the second brightest star in the Orion constellation. Image courtesy of Oisin Trust.

This also seems to be the case for Betelgeuse. Faison agrees that it is an unstable star, which has been blowing off gas and pulsating, all indications that it will go supernova soon.” But in a universe where the lifetime of even the most short-lived of stars dwarfs the time-span that humans have been on Earth, an astronomer’s concept of “soon” is quite different than a layperson’s. According to Faison, “Betelgeuse could very well go up tonight, but it could also happen any time in the next hundred thousand years.” Being able to predict the time of a supernova with any accuracy is currently impossible. The inherent difficulty is that there is no way to probe the core of a star, where the catastrophic collapse occurs, in order to determine its chemical and physical composition.

Faison was quick to add that contrary to any doomsday theories, the supernova is much too far away to pose any threat to Earth. In fact, the tremendous energy of supernovae made life on Earth possible by producing elements heavier than iron, which normally cannot be synthesized in a star by nuclear fusion. The last supernova that occurred in our galaxy, which was also the last to be visible by the naked eye, took place in 1604 and is sometimes referred to as Kepler’s Supernova. Even at the considerable distance of about 20,000 light-years, this phenomenon was still visible during the daytime for three weeks. Thus, at the much shorter distance of about 430 light-years from Earth, a Betelgeuse supernova would truly be a spectacular sight. While it would not be nearly as bright as the Sun, the supernova’s brightness is expected to rival that of the full Moon. The beauty of a supernova, however, is not all that gets scientists excited about the idea of one in our galaxy. It would also provide the opportunity for a star to be examined extensively both before and after a supernova, and Betelgeuse is just one among a list of candidates that scientists are currently studying.

Based on observations of other galaxies, Faison notes that astronomers expect our galaxy to experience a supernova about every 100 years. This would mean that a supernova is long overdue in our galaxy, a fact that tantalizes astronomers hoping to witness one of the most dramatic phenomena in the universe. Perhaps the only thing that manages to impress us more than the spectacular beauty and magnificence that space holds is its endless ability to keep us guessing.

Mansur Ghani
By Mansur Ghani May 12, 2011 18:22