Deep within LHA 120-N 180B, an HII region located in the Large Magellanic Cloud, the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope has spotted an ionized jet emitted by a massive young stellar object. This is the first time such a jet has been observed in visible light outside the Milky Way. Usually, such jets are obscured by their dusty surroundings, meaning they can only be detected at infrared or radio wavelengths. However, the relatively dust-free environment of the Large Magellanic Cloud allowed this jet to be observed at visible wavelengths.
The HII region LHA 120-N 180B resides in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. At only around 160,000 light-years away from the Earth, it is practically on our doorstep. Image credit: ESO / A. McLeod et al.
HII regions are interstellar clouds of ionised hydrogen — the bare nuclei of hydrogen atoms.
These regions are stellar nurseries — and the newly formed massive stars are responsible for the ionization of the surrounding gas, which makes for a spectacular sight.
The distinctive shape of the HII region LHA 120-N 180B is made up of a gargantuan bubble of ionized hydrogen surrounded by four smaller bubbles.
Deep within this glowing cloud, MUSE spotted a jet emitted by a fledgling star — a massive young stellar object with a mass 12 times greater than our Sun.
Named Herbig-Haro 1177 (HH 1177 for short), the jet is shown in detail in the new MUSE image.
This image shows a close-up of the Herbig-Haro 1177 jet source and the bow shocks formed by the jet interacting with surrounding gas. Image credit: ESO / A. McLeod et al.
This is the first time such a jet has been observed in visible light outside the Milky Way, as they are usually obscured by their dusty surroundings.
However, the relatively dust-free environment of the Large Magellanic Cloud allows the jet to be observed at visible wavelengths.
At nearly 33 light-years in length, it is one of the longest such jets ever observed.
This jet also tells us about the early lives of stars.
The beam is highly collimated; it barely spreads out as it travels. Jets like this are associated with the accretion discs of their star, and can shed light on how fledgling stars gather matter.
Astronomers found that both high- and low-mass stars launch collimated jets like HH 1177 via similar mechanisms — hinting that massive stars can form in the same way as their low-mass counterparts.
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Anna F. McLeod et al. 2019. A parsec-scale optical jet from a massive young star in the Large Magellanic Cloud. Nature 554: 334-336; doi: 10.1038/nature25189
