Sabine
patreon
There's a mysterious dark patch in the Milky Way, and it's weirder than we thought.
🕑 Added 2023-12-18 16:00:08 +0000 UTC[This is a transcript with links to references.]
The Brick is a boxy cloud of opaque dust at the centre of the Milky Way, which has confused scientists ever since its discovery 30 years ago. It just got even weirder.
Astrophysicists originally thought that the Brick was just full of dense gases, which would absorb light. But then it should also have been full of young stars born from this dense gas. Yet those are nowhere to be seen. In reality, the Brick is closer to a nunnery than a maternity ward.
According to the new paper by an international team of astronomersnow, the Brick is full of ice crystals, made of carbon monoxide. Carbon monoxide is one of the gasses coming out of car exhaust pipes. You normally don’t see it as ice though, or if you do, maybe you accidentally drove to Saturn, because the freezing point of carbon monoxide is minus 205 degrees Celsius.
And that’s the stuff the researchers say is in the Brick. They figured this out with Webb’s infrared telescope. They used this to measure how much of the light that came from the other side of the brick was filtered out by it. From this they learned it contained significant amounts of this carbon monoxide ice.
This is extremely weird because according to our current models of galaxy formations such a cloud just shouldn’t be there. No one has any idea at the moment how it got there or what it’s doing there, it’s very confusing. It’s also very interesting because astrophysicists are still trying to understand the distribution and structure of matter in galactic centers which is super important for the debate whether dark matter of modified gravity is correct.
Though I think it’s just a huge traffic jam and it’s exhaust fumes from alien spacecraft.
Comments
Hello Tracey, figuered interesting, what Sabine reported too, that there are no star births in the Brick. Shouldn´t that be, since starburst regions are molecule clouds, which are cold and dark (well, as far as I know)?
The 2nd option, the Brick is particularly rich, but that may be a bit unfair because it is more studied, being near the galactic center. There could be other, richer molecular clouds that are in confused lines-of-site that are not on anyone's radar.
Thanks, Tracey. So probably not a one-off, even in our galaxy. That is not bad. Did you mean that dark galactic clouds are common, because they certainly are, but not many are rich in carbon as the Brick? Or that there are many nebular clouds also rich in carbon, but the Brick is the champion one?
Hey Oscar, "dark" molecular clouds with notable CO gas are quite common in the Milky Way and in other galaxies. The special thing about the "Brick" is that it is a particularly dense molecular cloud with particularly strong CO absorption. The neat thing about JWST is that the part of the spectrum it sees is rich in CO spectral lines. Previous ground-based data in this spectral range had hints of interesting spectral features, but the data quality really sucked compared to JWST. The CO absorption is so strong that the temperatures must be cold enough to get at least some partial ice formation, which had only been hypothesized before, but now is confirmed. I suspect that if we look at other interesting molecular clouds that high CO densities and CO ice might be found in them as well -- it'll just take some time for JWST to get pointed at less interesting sources. The location of the "Brick" near the Galactic Center isn't particularly interesting, at least to me. The time between "heating events" such as supernova shocks, spiral density waves, galactic mergers, black hole outburst, etc is the important thing and how quickly the different components (dust, gas) of the interstellar medium cool, especially in the presence of magnetic fields. Yes, that animation of JWST is particularly unfortunate.
