Almost 17 years ago, amateur astronomer Robert Evans was gazing at the outskirts of the NGC 7424 galaxy in the Grus constellation roughly 40 million light-years from Earth when he noticed a burst of light. He reported his findings to researchers at the International Astronomical Union who, just a year later, classified what Evans witnessed as a supernova they named SN 2001ig.
Supernovae are usually the cataclysmic death of massive stars that have run out of fuel to keep themselves burning. However, the star that caused SN 2001ig didn’t burn through all of its power source on its own. A devious companion star siphoned off nearly all of its hydrogen, essentially hijacking the star’s only life source and dooming it to perish in a massive explosion. Years after this stellar robbery was noticed, a group of international astronomers used the Hubble Space Telescope to capture an image of the object responsible for this cosmic crime.
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In a paper published Friday in the Astrophysical Journal, the team explained how this was the first time a murderous star of this nature was photographed. SN 2001ig is categorized as a Type IIb stripped-envelope supernova, an unusual end to a star’s life because most of its hydrogen is gone prior to the explosion. Scientists weren’t exactly sure what was responsible for this sudden loss of gas, but now they’ve caught a culprit red-handed.
“We know that the majority of massive stars are in binary pairs,” says Stuart Ryder, the lead author of the study, in a statement. “Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together.”
This graphic illustrates the scenario for the processes that create a Type IIb stripped-envelope supernova, in which most, but not all, of the hydrogen envelope is lost prior to the primary star’s explosion.
Based on this discovery it would seem that binary star systems — or a group of two stars circling each other — are main causes for this specific type of supernova.
Millions of years before the primary star of this system died its fiery death, its not-so-friendly neighbor was sucking up hydrogen from its stellar envelope — the region that transports energy from the star’s core to its atmosphere. The effectively shortens the primary star’s lifespan until it becomes so unstable that it goes supernova. Then all that’s left behind is the stellar thief and the massive cloud of dust expelled by the deceased star.
Now that they’ve found a feasible explanation to how some stars lose their hydrogen, the group wants to take this a step further and see if they can find other examples of this stellar robbery across the universe. They hope to make use of the James Webb Space Telescope to aid them in their search.
So if you thought space was only out to get humans, there is literal stellar murder happening above our heads. Yikes.
