Astronomers discover young star with dense disk outside our galaxy
For the first time, astronomers have observed a young star outside the Milky Way that is surrounded by a dense disk where planets can form.
Named HH 1177, the massive star and its rotating disk were discovered in the Large Magellanic Cloud, a neighboring dwarf galaxy located about 160,000 light-years away. This unprecedented finding could help scientists better understand the formation of stars and planets.
Newborn stars grow in size by absorbing matter from their surroundings, which accumulates in a flat disk around the star known as an accretion disk due to strong gravitational forces. This disk transports matter towards the star, making it larger. The greater the mass of the star, the more powerful its gravitational field becomes, drawing more gas and dust into the disk.
A star like HH 1177 forms more quickly and only has a fraction of the lifespan of a star like our Sun. Its shorter lifecycle makes it difficult to observe the early stages of a massive star in our galaxy, as the star and its disk are hidden from view by the dusty material from which it forms.
However, the material from which stars form in the Large Magellanic Cloud is different from that in the Milky Way, as it contains less dust and a lower abundance of metals, which gives a distant but clear view of stars.
The discovery of HH 1177 lies within a stellar nursery called N180, where the star is not obscured by a cocoon of gas and dust, providing a rare opportunity to study planetary formation in another galaxy.
The star was discovered using the Atacama Large Millimeter/submillimeter Array of telescopes in Chile, known as ALMA, and the findings were published Wednesday in the journal Nature.
The ALMA observations followed an earlier detection made by the European Southern Observatory’s Very Large Telescope. The Multi-Unit Spectroscopic Explorer, or MUSE instrument, on the telescope captured a jet of material released from the young star. Scientists initially discovered a jet launched from HH 1177, indicating the disk’s continued accretion.
The team needed to measure how fast the dense gas was moving around the star to discern whether there was a disk around the star. ALMA observations allowed detailed measurements of the disk’s spin.
The frequency of light changes depending on how fast the gas emitting the light moves towards or away from us, according to Dr. Jonathan Henshaw, a researcher at Liverpool John Moores University, United Kingdom. This change in frequency helped determine the existence of a disk around the star.
The ability to study stars’ formation at such incredible distances and in a different galaxy is very exciting, noted study lead author Dr. Anna McLeod, associate professor in physics at Durham University, United Kingdom. The findings mark a significant advancement in our understanding of how stars form in the universe.