Scientists have detected a huge jet of material being ejected by a star, potentially revealing the mystery of how massive stars form.
Led by the University of Canterbury in New Zealand, the research is published today in Nature. Using the Very Large Telescope (VLT) in Chile, the team were able to study the star located about 160,000 light-years from Earth in the Large Magellanic Cloud (LMC), one of our neighboring galaxies.
Dubbed HH-1177, the jet is huge, spanning about 36 light-years. From our perspective, the jet has two lobes, or ends, one of which is moving towards us and the other away. It was observed in optical light, something that’s rare for young stars like this.
“The jet is one of the largest jets of its kind ever found,” Dr Anna McLeod of the University of Canterbury told IFLScience. “It is the first optical jet from a massive young star detected outside of our own galaxy!”
In the images above, taken by the VLT, we zoom into the region where this jet is. It's located at the "top" of a pillar of dust and gas, and we can see that it's firing towards and away from us thanks to its redshift and blueshift. In the upper right image, we can also see the bow shocks caused by the jet firing through the cloud of dust and gas.
The discovery is important because it gives us a glimpse into how massive stars form. We’ve got a pretty good understanding of how stars similar to our Sun form, but we aren’t very good at stars bigger than eight solar masses. This particular star is 12 times more massive than our Sun.
Smaller stars grow by eating material in swirling disks of dust and gas around them, known as accretion disks. Something similar had been theorized for more massive stars, but it was hard to find out because these objects are typically hidden by large clouds of dust and gas.
Jets like this, however, are thought to be directly linked to that accretion process, with the star firing out material in both directions. Although we don’t know exactly how they form (it's perhaps linked to the star’s rotation and magnetic field), we know that an accretion disk must play a part.
“The presence of a jet of this extent indicates that the massive star has been regularly accreting matter,” said Dr McLeod.
“This discovery therefore strongly supports the growing evidence that massive stars form via a scaled-up version of the mechanism that forms low-mass stars.”
In the future, the team hope to get more views of this jet so that they can see how fast it's moving. Coupled with previous observations, this could tell us a bit more about how massive stars get so, well, massive.