Astronomers Spot the Moment a Massive Protostar Develops Powerful Jets

For the first time ever, astronomers have spotted the moment in which a massive protostar begins to develop jets of matter and energy crucial for star formation. The findings reveal a bit more about stellar evolution.

Stars are formed inside relatively dense concentrations of interstellar gas and dust, known as molecular clouds. When denser parts of the cloud core collapse under their own weight and gravity, then stars are formed. Accretion of material onto the embryo star continues partially from the newly formed circumstellar disk. In this stage, bipolar jets are produced, which are the means by which infalling material is expelled.

The phenomenon of collimated outflows happens in diverse astronomical objects; for example, it occurs in young stars, black holes in galactic nuclei and stars at the ends of their life cycles. However, how collimated outflows begin and what factors regulate their degree of collimation remain unknown.

That's why researchers took a look at the massive protostar W75N(B)-VLA2. This revealed the transition from the first regime in which the star ejects matter in all directions, and a second regime in which the ejection is along a preferred single direction, forming the jet. Although star formation processes trigger hundreds of thousands of years, researchers have been able to observe how the wind from the protostar has evolved from a compact to an elongated source in only 18 years.

"The study opens a new exciting window of opportunity to study how the basic ingredients of star formation evolve over the next few years," said Jose Maria Torrelles, one of the researchers, in a news release. "We are lucky to be on the brink of describing and modelling in 'real time' all of these rapid changes."

The findings are published in the journal Science.

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