There is a sparkling beauty in cosmic death.
In a new image from JWSTthe spectacular final pangs of a star at the end of its life are revealed in all their detail.
Located in the constellation Sagittarius, ta star WR 124 is called a Wolf-Rayet, which are rarely seen in the Milky Way. This is because only certain stars transform into Wolf-Rayets, and even then their time in this phase is so short; in a few hundred thousand years, WR 124 will explode into a glorious supernova.
Wolf-Rayet stars may be some of the most spectacular stars in the galaxy. They are very hot, very bright, igniting in a final cry of light at the end of their main sequence life as their fusion fuel runs out.
At this point, they are significantly depleted in hydrogen, but rich in nitrogen or carbon. They also lose mass at a very high rate. The mass they lose is also rich in carbon, which absorbs the radiation and re-emits it as infrared light. This makes it a very attractive target for the JWST, which is not only the most powerful space telescope ever built, but also produces the highest resolution infrared and near-infrared images.
WR 124 is a Wolf-Rayet star that has already lost quite a bit of mass; it is surrounded by an elaborate cloud of its own ejected material, marked with filaments and knots as it expands in space around the star, glowing in infrared light as it cools. We know from previous observations that this cloud is a fascinating and complex tangle, but until now it lacked enough high-resolution detail to understand the intricacies.
For example, when WR 124 eventually explodes, are the dust grains in its nebula large enough to survive the supernova? Learning this could give astronomers important insight into the contribution of Wolf-Rayet stars to the interstellar dust budget – material that then becomes incorporated into other stars and planets as they form.
It could also help identify supernova remnants left behind by Wolf-Rayet stars, which could tell us how they explode. Astronomers believe Wolf-Rayet stars are the ancestors of type Ib and type Ic supernovae, but definitive evidence is scarce; understanding the dust emitted by the star before death could help connect the stars to the clouds of debris they leave behind.
Interestingly, WR 124 belongs to a mysterious category of Wolf-Rayet stars that traverse space at enormous speeds compared to the rotational speed of the galactic disk itself. WR 124 is one of the fastest stars in the Milky Way, with a speed of 190 kilometers (118 miles) per second.
We don’t know why he’s hurtling through space so fast, but recent search suggested it was in a binary system with another dying star, whose own supernova knocked WR 124 out of its position in the galactic disk.
JWST data may or may not help unravel this mystery; it doesn’t seem to be a high priority. We just think it’s really neat.
You can download a high resolution version of the new image from the NASA website.