Astronomers have looked at the very heart of a supernova and discovered tangled clumps of gas and dust surrounding the remains of an exploded star. The object in question is Supernova 1987a, and while its image is famous, we have never seen it in three dimensions before.
The 3D reconstruction was possible thanks to the Atacama Large Millimeter/submillimeter Array (ALMA). A sister study based on the observations has already revealed unexpected chemistry in the region. The new work, published in the Astrophysical Journal Letters, reveals where those newly formed molecules are located.
“When this supernova exploded, now more than 30 years ago, astronomers knew much less about the way these events reshape interstellar space and how the hot, glowing debris from an exploded star eventually cools and produces new molecules,” co-author Rémy Indebetouw, an astronomer at the University of Virginia and the National Radio Astronomy Observatory (NRAO), said in a statement. “Thanks to ALMA we can finally see cold ‘star dust’ as it forms, revealing important insights into the original star itself and the way supernovas create the basic building blocks of planets.”
Supernovae are key to the formation of new stars and planets. When a star that's about 10 times the mass of the Sun runs out of fuel to perform nuclear fusion, it collapses on itself. The energy released in the collapse blows the star apart, leaving a dense object (either a neutron star or black hole) at its core.
The blast is also capable of creating and spreading heavy elements, and those elements will mix with hydrogen to form new stars. The heavy elements affect the size and life expectancy of stars and this has an impact on the galaxy as a whole.
“The reason some galaxies have the appearance that they do today is in large part because of the supernovas that have occurred in them,” he added. “Though less than 10 percent of stars become supernovas, they nonetheless are key to the evolution of galaxies.”
Supernova 1987a is the closest supernova we have observed in the last 400 years, but it’s not in our galaxy. It is in the Large Magellanic Cloud, the largest satellite galaxy of the Milky Way, about 163,000 light-years away. It’s one of the best-studied supernova remnants and yet it still has its mysteries.
Future studies will hopefully provide answers to the most pressing questions. How are the newly discovered molecules distributed? What kind of object is actually at the center? A pulsar or a regular neutron star? More data is needed, and hopefully ALMA will provide just that.