STELLAR LIFECYCLES

Hi, I’m Marley, the Astronomer here at the Space Centre. This month, I wanted to check back in with the James Webb Space Telescope (JWST) and the science surrounding one of the themes we are exploring this year. In April, we discussed scientific discoveries about galaxies, in July we looked at other worlds, and this month we will be checking out stars!

One of Webb’s scientific themes is on the stellar life cycle. Being an infrared telescope, Webb is able to see through clouds of dust where newborn stars and planetary systems hide. Observing and studying stars from their birth until their death help us understand the complexities around star and planet formation. And hopefully, answer questions surrounding how clouds of dust and gas collapse to form stars, and how they release heavy elements back into space when they die.

Stellar Birth

All stars are born from swirling clouds of dust and gas known as nebulae, but the intricate processes involved to form the stars are still not fully understood. On July 26th, JWST released an image of Herbig-Haro 46/47,  a pair of actively forming stars. This system is only a few thousand years old, and stars take millions of years to fully form. You can’t see the stars directly, they are buried deep inside of a disk of gas that feeds their growth. Additionally, you can see large lobes coming from the central region. A lot of this material has been shot from the stars as they have ingested and ejected the gas and dust that surrounds them. How much material a star ingests and ejects will influence how much mass the stars will have, which will influence the life of the star itself. Studying this system in particular can tell scientists about how stars accumulate mass over the years, which can lead to new insights about how stars like our Sun formed in the past.

Stellar Death

A supernova is a large release of energy, and some of the brightest events in the universe. Astronomers distinguish between two types: ones that involve white dwarfs, and the ones that come from the deaths of very massive stars. These explosions create and spread new elements through space, which ultimately become the building blocks for new stars and planetary systems.
On August 31st, JWST released an image of SN 1987A, a supernova remnant approximately 168,000 light years away, in the Large Magellanic Cloud. This supernova has been a target of study for nearly 40 years, with observations ranging across the electromagnetic spectrum. Using NIRCam, scientists can learn more about how a supernova remnant changes over time.

The Hubble Space Telescope and the Chandra X-Ray Observatory have viewed this supernova as well, but JWST provides a deeper view. Now seen are small crescent like structures near the central ‘keyhole’ region of the supernova. Scientists think that these crescents are from the outer layer of gas from the supernova explosion. However, our viewing angle of the supernova may make it seem like there is more material there, an optical phenomenon called limb brightening.

Even though JWST provides a much clearer and in depth view of this supernova, there are still several questions that scientists have about it. Many of these concern the neutron star that should be in the centre of this explosion. Thus, JWST will continue to observe SN 1987A, and collaborate with other observatories to gather more insight.

Studying the life of a star gives us insight into the star itself, but also into the birth and evolution of planetary systems. As JWST continues into its second year of scientific observations, be ready for new insights and discoveries that concern both stars and their planets. In the meantime, check out some stellar activities below.