(University of Alberta)
EDMONTON — In the Messier 82 (M82) Galaxy 12 million light years away, there’s a stellar fight taking place between a star and its deceased neighbour. The neighbour, an ultraluminous X-ray source, is thought to be the core of a dead star that is quickly devouring its companion. Discovery of this cosmic event has sent waves throughout the astronomy world, shattering theories and making scientists rethink their understanding of the lives of stars.
Until recently, experts had thought that only black holes can produce these bright sources of X-rays. After taking a closer look at one such X-ray source, astronomers realized the light was actually pulsing, like a flashing light. This phenomenon is only known to occur in stellar bodies called pulsars, the core of a dead star that spins rapidly while shining a thin beam of radiation, much like a lighthouse. Typically, a black hole will pull stars and other material towards it. In the extreme environment surrounding the black hole, X-rays are emitted.
Now it appears that a smaller pulsar can achieve the same level of X-ray emissions using their gravity and strong magnetic field.
NASA has reached out to Jeanette Gladstone, the University of Alberta Observatory’s director of public education and outreach, to give expert analysis of the event. Gladstone, a postdoctoral fellow at the U of A, has been studying ultraluminous X-ray sources for eight years.
“We were just starting to come to some kind of agreement that these were stellar remnant black holes, like 15 to maybe 50 times the mass of our sun, being a bit weird,” Gladstone said. “We’d only just after all this time managed to come to an agreement — and this basically tells us that it’s probably not right.”
The pulsar in M82 has the energy equivalent of about 10 million suns, but is small enough to fit within the boundary of the Anthony Henday Drive. It pulses every 1.37 seconds and, according to NASA, it’s the brightest pulsar ever observed.
This discovery was made unintentionally — astronomers were observing an unrelated supernova explosion when someone decided to look at X-ray sources elsewhere in the galaxy.
Now theorists and astronomers will have to sift through existing information and gather new data to help establish what exactly is happening in these pulsars that makes them so bright, Gladstone said. After studying ultraluminous X-ray sources for eight years, Gladstone said she is unwavering in her interest for the unknown.
“I’m really excited by it actually,” Gladstone said. “We still don’t understand this. This is still really crazy.”
With this new discovery comes fresh clues to understanding the formation of everything in the universe, including Earth.
“It will help us to understand these rapidly growing black holes in the early universe, and if you can explain how to grow super-massive black holes, you can explain a bit more,” Gladstone said. “You can find out about how to grow galaxies, because we know there’s a link between the two.
“How do you form these places that can create stars, that can create planets, that can create life?”
Those interested in astronomy can visit the University of Saskatchewan observatory on Saturday nights for some stargazing. Public visiting hours are available online at artsandscience.usask.ca/physics/observatory/hours.php
Photo: James Davison