The mysterious innards of a dense, dark cloud at the heart of the Milky Way are finally being revealed.
Using the James Webb Space Telescope, a team of astronomers led by Adam Ginsburg of the University of Florida managed to observe the interior of a cloud called G0.253+0.016, better known colloquially as The Brick because it is very dark, dense and opaque.
And what the researchers found there presents a bit of a problem, because it’s at odds with what we understand about how these clouds work.
This, in turn, means we may have to rethink our understanding of star formation, the team says.
The center of the Milky Way is a strange place. On the one hand, there is that supermassive black hole, right in the middle. That environment is wild thanks to the black hole and its gravity.
But around the black hole there is a region densely populated by very thick molecular clouds. This is known as the Central Molecular Zoneand it is something like the smoggy capital of the Milky Way: the density of molecular gas there is several orders of magnitude greater than in the galaxy’s disk.
This is really interesting to astronomers, because thick molecular gas is the stuff from which stars form. Overdensities in cold clouds collapse under gravity to form seed stars, which grow by pulling more material from the surrounding cloud.
There is only one problem. These clouds are really super thick, so thick that it is impossible, at most wavelengths, to see what is inside them.
The Brick is a particularly egregious example. It is one of the densest molecular clouds in the Milky Way. But the JWST has a superpower. It sees the Universe in infrared light, and that’s the wavelength range that can penetrate thick clouds of dust and gas where Shorter wavelengths are scattered..
Then Ginsburg and her team focused the telescope golden honeycomb eye to the galactic center, to contemplate the heart of The Brick.
And there they found something they didn’t expect. Carbon monoxide (CO) ice. Absolute piles of that stuff. Much more than they had anticipated, suggesting that the Central Molecular Zone is rich in it.
“Our observations convincingly demonstrate that ice is very common there, to the point that any future observations will have to take it into account,” ginsburg said.
The presence of so much CO ice suggests that The Brick should be forming stars; but is not. In fact, the lack of star formation detected in the cloud has puzzled scientists before, and several explanations have been proposed, including high turbulence and a relatively young age for the cloud itself.
Ginsburg and her colleagues found another explanation. Remember how we mentioned that stars form from cold gas? Inside, The Brick is significantly warmer than other similar clouds. It’s not clear why, but additional research and analysis could yield some clues.
The abundance of CO also suggests that both the amount of CO and the dust-to-gas ratio (as CO ice binds to dust particles) have been significantly underestimated and underestimated in the galactic center.
This is just the first of the team’s findings from JWST observations of The Brick. The work continues, and Ginsburg and his colleagues hope to find some answers soon.
“We don’t know, for example, the relative amounts of CO, water, CO2 and complex molecules.” Ginsburg says. “With spectroscopy, we can measure them and get an idea of how the chemistry progresses over time in these clouds.”
The research has been published in The Astrophysical Journal.