Location of supernovae SN 2004et and SN 2017eaw in the galaxy. Illustration: KPNO, NSF's NOIRLab, AURA
The James Webb Space Telescope has taken a direct look at cosmic dust clouds around two supernovae in another galaxy. This made it possible to confirm the hypothesis of the formation of cosmic dust as a result of explosions of massive supernovae.
The supernovae SN 2004et and SN 2017eaw observed by astronomers were recorded in 2004 and 2017 in the galaxy NGC 6496, about 22 million light-years away. To detect cosmic dust, measurements in the mid-infrared range were used. When a cloud of gas from a supernova explosion cools enough to form dust, the dust can only be seen in this range if the telescope is sensitive enough. The Mid-Infrared Camera of the James Webb Telescope (MIRI) is the only way to see the dust cloud around such distant supernovae.
The researchers were also able to measure the amount of dust in the cloud, which turned out to be on the order of 5,000 Earth masses. This is the largest amount of dust around a supernova observed since measurements of the dust cloud around supernova SN 1987A in our neighboring galaxy, the Large Magellanic Cloud.
Astronomers also found that a cloud of cosmic dust managed to survive the shock waves propagating in the cloud after a supernova explosion.
Cosmic dust serves as the "building material" for many objects in the universe: for planets and the next generations of stars. Dust carries elements heavier than hydrogen and helium, which eventually lead to the formation of conditions suitable for the emergence of life. Scientists assumed that one of the sources of cosmic dust would have to be supernova explosions, but for a long time they could not directly observe how and where the dust comes from, so its origin remained a mystery.
It is known that distant, that is, the youngest, galaxies are full of dust, but their age is not enough for stars with intermediate masses like the Sun to have time to produce this dust. Therefore, for the formation of dust in the galaxy, generations of heavy stars had to arise and die. Thanks to the observations of "James Webb", scientists have come to the conclusion that supernovae can rightfully be considered cosmic "factories" of dust.