Webb telescope reveals new images of the mysteries of the universe
For the first time, astronomers have observed a young star outside of our Milky Way galaxy that is surrounded by a dense disk capable of forming planets.
The star, named HH 1177, along with its rotating disk, was discovered in the Large Magellanic Cloud, a neighboring dwarf galaxy located approximately 160,000 light-years away. This groundbreaking discovery has the potential to enhance our understanding of star and planet formation.
When a newborn star grows, it absorbs matter from its surroundings. Due to strong gravitational forces, gas and dust accumulate in a flat disk known as an accretion disk. This rotating disk transports matter towards the star, causing it to grow larger. The star’s mass determines the strength of its gravitational field, which in turn attracts more gas and dust into the disk.
An extraordinary finding
An artist’s illustration depicts the HH 1177 system, situated in the neighboring galaxy called the Large Magellanic Cloud. The massive young star at the center draws in gas and dust from a rotating disk, while also expelling matter in the form of jets.
HH 1177, a colossal star, lives fast and dies young. It forms more rapidly and has a lifespan much shorter than that of our Sun. This makes it challenging to observe the early stages of a massive star within our own galaxy, as both the star and its disk are concealed by the dusty material from which they form.
However, the material within the Large Magellanic Cloud, where stars form, differs from that of the Milky Way. HH 1177 resides in a stellar nursery called N180, which contains less dust and a lower abundance of metals. As a result, the star is not obscured by a cocoon of gas and dust, providing a clear but distant view.
«When I first observed evidence of a rotating structure in the ALMA data, I couldn’t believe that we had detected the first extragalactic accretion disk – it was a special moment,» said Dr. Anna McLeod, the lead author of the study and an associate professor in physics at Durham University in the United Kingdom. «We know that disks are crucial for the formation of stars and planets in our galaxy, and here, for the first time, we are seeing direct evidence of this in another galaxy.»
Dynamic activity of a young star
The ALMA observations were conducted as a follow-up to a previous detection made with the European Southern Observatory’s Very Large Telescope. The Multi-Unit Spectroscopic Explorer (MUSE) instrument captured a jet of material released from the young star, which was found deep within a gas cloud in the galaxy.
«We discovered a jet launched from this massive young star, and its presence indicates the continued accretion of the disk,» explained McLeod.
To determine the presence of a disk around the star, the team needed to measure the speed at which the dense gas was moving around it.
When matter is attracted to a young evolving star, it forms a disk-shaped structure that flattens and rotates around the star, rather than falling directly onto it. The disc spins faster at its center. By analyzing the difference in speed, astronomers can determine whether a disk has formed around a star.
The ALMA observations provided detailed measurements of the disk’s spin.
Accretion disks are not exclusive to young stars; supermassive black holes also possess thin, hot disks of matter that swirl around them and serve as a source of sustenance.
«We are currently experiencing a period of rapid technological advancements in astronomical facilities,» McLeod stated. «The ability to study the formation of stars at such incredible distances and in a different galaxy is truly exciting.»