Stars can last for billions of years, with lifetimes that humans can only dream of, but sometimes they can change in an instant.
At least that’s the case with SN 2014C, a star gone supernova discovered by scientists in 2014. This “chameleon supernova” changed appearance dramatically, shifting from a Type 1 supernova (with very little hydrogen present) to a Type 2 supernova (with a lot of hydrogen present) in a single year.
SN 2014C This unusual supernova (outlined in a box) has changed appearance dramatically in just a year. Credit: NASA/CXC/CIERA/R.Margutti et al
In an article published in The Astrophysical Journal researchers announced that they might have figured out why the star changed appearance so quickly.
Using NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) satellite, the researchers found that the star had thrown off a huge mantle of hydrogen years—if not centuries—before it exploded. That meant that initially when the star was first observed from Earth, it appeared to be very low in hydrogen. But when the star exploded, the shock waves traveled through the cast-off hydrogen, heating them and making the star appear hydrogen rich.
This visible light image shows the chameleon supernova SN 2014C in it’s location in galaxy NGC 7331. The image in the left box shows how the area appeared before the explosion, the right shows the area after. Credit: X-ray images: NASA/CXC/CIERA/R.Margutti et al; Optical image: SDSS
Researchers still don’t know how or why the star threw away so much hydrogen before it exploded. They do know that the massive star got rid of quite a bit; expelling the equivalent of the mass of our Sun into its surrounding environment.
“The notion that a star could expel such a huge amount of matter in a short interval is completely new,” said Fiona Harrison, NuSTAR principal investigator based at Caltech in Pasadena. “It is challenging our fundamental ideas about how massive stars evolve, and eventually explode, distributing the chemical elements necessary for life.”
A galaxy far, far away NGC 7331is located between 36 million and 46 million light years away. The center, seen in an x-ray inset likely contains a supermassive black hole. Credit: ASA/CXC/Ohio State Univ./C.Grier et al.; Optical: NASA/STScI, ESO/WFI; Infrared: NASA/JPL-Caltech
The material in stars or ‘star stuff’ as it was described by Carl Sagan, is full of basic elements that make up almost all matter in the universe. By sending that material out into the environment, the star is essentially seeding its surroundings with the material to become parts of other solar systems.
Figuring out the mechanisms behind the expulsion could help astronomers piece together more information about the life cycle of stars, including stars like our own.