NASA’s Webb Space Telescope has used its extraordinary infrared imaging capability to reveal heretofore unseen star formation in the nearby so-called ‘Cosmic Cliffs,’ part of NGC 3324, a star forming region located some 7200 light years away in the Carina Nebula.
Webb has peered into a star-forming nursery not unlike the one we think gave birth to the Sun and Solar System, Megan Reiter, an astronomer at Houston’s Rice University and the study lead, told me. The Cosmic Cliffs are the dust and molecular gas edge of the star-forming cloud that gave birth to the NGC 3324 cluster, she says.
These infrared images let us see the warm glow of young stars still buried in their natal cocoons and dozens of the molecular hydrogen outflows that they drive during the brief period of their active accretion, says Reiter. These observations reveal 24 molecular outflows from very young stars that are still in the process of putting themselves together, she says.
These outflows are an unambiguous signpost of star formation tracing the most active assembly phase, says Reiter. She notes that the region observed is not even the most active star-forming part of NGC 3324.
The team detailed their findings this month in The Monthly Notices of the Royal Astronomical Society (MNRAS).
The dense clouds that initially formed this region have given birth to a bunch of massive stars that are now carving out a big cavity, which is filled with hot ionized gas, Nathan Smith, an astronomer at the University of Arizona in Tucson, and one of the paper’s co-authors, told me.
As the cloud is being destroyed by the massive stars, the dense regions that are swept up are also rapidly giving birth to new lower mass stars that will evolve to be more like our own Sun. These newly forming stars are also spawning high-velocity jets of gas and dust that stream out from the stars’ poles.
For a brief part of this time, material is being pulled in by the gravity of a newly forming star, and these jets are driven out in the process.
Material squirts out into interstellar space far from the star that is forming, says Smith.
These jets then act like a snowplow, bulldozing into the surrounding environment, says NASA.
“Jets like these are signposts for the most exciting part of the star formation process,” Smith said in a statement. “We only see them during a brief window of time when the protostar is actively accreting.”
Surprisingly, this star-forming region is more typical than many of the very nearest star forming regions near Earth, which lack the most massive stars.
It’s more common for stars to form in regions with massive stars nearby, simply because such regions have more mass in the clouds and just form way more stars, Smith told me. Our Solar system probably formed in a more massive region like NGC 3324, he says. But the Sun has drifted far from its birth site in the past 4.6 billion years, and all the massive stars it was born with are long since dead, says Smith.
What’s most puzzling about these images?
These outflows are not long continuous streams like water from a firehose, but most look like a chain of a few dense clumps moving fast, says Smith. This tells us that the process of jet launching (and hence the process of growing mass onto the star) happens in a series of a few short and powerful bursts, he says. Understanding why it is so unsteady and how that affects the physics of how stars grow in mass is a challenge, says Smith.
“I’d like to look at the rest of the Carina Nebula,” said Smith. “These Cosmic Cliffs are just a small section of a very large and active region of massive star formation.”