Astronomers using the ALMA Observatory have discovered a star that has two spiral arms. A broad disk of dust and gas surrounds a star. Researchers think they can track the formation of the spiral arms to a close encounter the star had with another object.
The disks can stretch out to hundreds of times larger than a young star. The disks feed gas from the environment to the growing stars.
Astronomers have been able to study distant stars with the help of newer telescopes like ALMA. A lot of the previous observations of these objects have been for Sun-like stars.
The star that was observed in this study is an early O-type star that is very hot and massive at 32 solar mass. There is a huge disk with a diameter of 4,000 units.
The researchers don't know if accretion disks play a role in the formation of this type of star. The environment of the entire universe is strongly impacted by these massive stars, which are hundreds of thousands of times larger than the Sun. Understanding the formation of massive stars is important.
According to a press release, the system is among the most massive protostars with accretion disks. A co-author of the study isZhang. It appears that the formation of massive early O-type stars goes through a phase with accretion disks involved.
There is a unique and important star-forming environment in the central region of the Milky Way. Sagittarius A* is the most well-known object in the region.
The raw material for star formation is a huge amount of dense hydrogen. Once the collapse starts, the gas will start forming stars. The distance between the center of the universe and the Earth makes it difficult to see star-forming regions. There are details of star formation in this region that need to be resolved with a high resolution.
The accretion disk clearly shows two spirals. In spiral and pinwheel galaxies where hundreds of millions of stars spiral together around a common core, spiral arms have been seen before. It is very unusual to find a case of spiral arms around a single star.
The team said in their paper that the disk is stable with two spirals. An analysis of analytical solutions and numerical simulations shows that the most likely scenario to form the spirals is through external perturbations caused by a close flyby.
The researchers were able to detect an object of about three solar mass at a distance. They reproduce a scenario where an object flew by the disk and perturbed it, causing the formation of spiral arms.
The simulations match perfectly with the ALMA observations. According to the lead author, the spiral arms in the disk are relics of the flyby of the object.
According to the astronomer, accretion disks at the early evolutionary stages of star formation are subject to frequent dynamic processes, which would influence the formation of stars and planets.
The solar system has had similar flybys in the past, most likely due to the Oort cloud sending comets to the innersolar system. Similar flybys are likely to be frequent in a high density environment.
Lu believes that the formation of stars should be a process of constant change. We expect to disentangle these mysteries with more upcoming high-resolution ALMA observations.
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