Hubble photographed the birth of a star

About 400-600 light-years away, in the southern constellation of Chameleon, a large cloud complex is turning into stars. These are very young newly formed Taurid T stars. If you look closely with the right tools, you can also see stars that are in the process of forming, known as protostars. The subject of the new Hubble photo is one of them, named J1672835.29-763111.64, embedded in the reflection nebula IC 2631 (which is a nebula that glows with reflected starlight; IC 2631 is illuminated by a star called HD 97300).

Stars form in cold, dense clouds of interstellar molecular gas. This gas is not evenly distributed; denser lumps can merge due to processes such as local stellar winds, which cause the gas to clump together. When the density is high enough, these lumps can collapse under their own gravity, forming a spinning protostar.

As a protostar rotates, the material in the cloud around the object forms a disk. This disc of material does compact then in the forming star, attracted by its gravity, which grows as the protostar gains mass. As the protostar grows, it begins to produce a powerful stellar wind, and the material falling into the protostar begins to interact with its magnetic fields, flowing along the magnetic field lines to the poles, where it is blown up into space in the form of powerful plasma jets.

Credits: NASA/ESA Hubble

The wind and jets are known as stellar feedback and help blow away the material around the protostar, slowing and eventually damping its growth. When the star gains enough mass to produce enough heat and pressure in the core, nuclear fusion will kick off. Any gas and dust that remains in the disk will then form other objects such as planets, asteroids and comets. That is why the planets of the Solar System and the asteroid belt are arranged more or less on a flat plane.

J1672835.29-763111.64 is not at that point yet. The region around it is still very dusty, which means it has not yet wiped out the material surrounding it. Usually, we wouldn’t be able to see the protostar glowing in the midst of all that dust, but infrared wavelengths can penetrate the cloud, which means Hubble’s infrared instrument can see it.

The protostar was observed as part of a targeted investigation of 312 of these objects, obscured by dense molecular clouds. Star formation is a relatively long process that takes place over millions of years, which means we will probably never be able to see it from start to finish.

We can learn more about it by identifying as many protostars as possible and getting as much information about them as possible. Smart astronomers then study the process by using these stars to work out a star-forming timeline and studying each of the phases in detail.

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