From my amateur understanding of space, it seems to be a galaxy made of just primordial hydrogen and helium, back before the first stars formed and started creating heavier elements due to the fusion reactions that power stars and the eventual supernovas that further dispersed and helped to create even more heavy elements.
Another cool theory is that the first stars are thought to have been much, much more massive, possibly up to around a thousand solar masses since they were made solely of hydrogen and helium. It’s estimated that current stars couldn’t get above a few hundred solar masses at most due to the existence of heavier elements in modern gas clouds. I don’t understand enough to explain why the existence of heavier elements limits star size so I’ll leave that to someone smarter than me.
Someone correct me if I got anything wrong, again I only have an amateur level of understanding about space.
I think the heavier elements exponentially speed up stellar death. In part, the fusion of elements makes the core denser and denser each step of the way. Going from hydrogen to helium is twice as dense, but helium is still a good fuel so it isn’t an issue. As fusion continues through carbon and oxygen, it shrinks but still burns. Iron is the tipping point though because it doesn’t work as a fuel at all - it triggers a core collapse, the surface falls into the void, and everything heavier than iron is instantaneously fused and thrown into the universe.
So I would guess the lesser abundance of heavier elements early on delayed that process compared to today’s standards. Sort of like making a snowman in fresh powder and having to melt/wet the snow to make it pack vs having a little rain and higher temps after the powder to wet it
The amount of heavy elements present in a star when it formed will be neglible to the amount that will be created over time through fusion.
You can actually detect this through spectroscopy because the initial amount of metals will be present in the outer layer of the star. Heavy elements made through fusion will be mostly in the core.
The reason stars formed from primordial gas, i.e. only consisting of hydrogen and helium, is that such a gas will fragment less as it cools and collapses. Less fragmentation means heavier stars.
I only have a high level knowledge of the process though.
Intriguingly, the two structures are at the same distance from Earth, near the constellations of Boötes the Herdsman, raising the possibility that they are part of a connected cosmological system.
Not only that, but they look suspiciously concentric when plotted out on the sky. I know that's jumping pretty far out there into speculation land, but it'd really blow our theories a new one if there are patterns in the cosmos this large. Neat stuff.
Obviously NASA engineers don't ever go to Youtube, I'm sure looking up "asteroid sampler stuck" there would have been a number of hack DIYers who showed a variety of techniques they've used.
A very cool idea, however the headline is misleading - NASA has not even remotely committed to running this mission. They’ve selected the swarm project as one of 13 projects in their innovation program and given it up to $175k to study feasibility. That’s roughly a postdoc for two years. This is far, far from committing the hundreds of millions or billions needed for the execution of this mission.
The laser array is expensive but if it’s continuous and spread out enough you could keep sending newer probes. Or if it’s not continuous you could use it for different directions!
According to Scott Manley’s video on the topic the probes would need to arrive at the correct time in order to form what is effectively a huge phased array antenna.
Only then is the combined transmission power of these tiny probes large enough to be received on earth.
As Universe Today explored in a previous post, it would take between 19,000 and 81,000 years for a spacecraft to reach Proxima Centauri using conventional propulsion (or those that are feasible using current technology)
Acceleration is a bitch. A manned flight would take longer as it would have to cap it’s thrust to 1-1.5G or risk long term effects. Not to mention having to cancel ALLL of that thrust starting at the halfway point.
Biology is frustrating. We’re built for everything except leaving the immediate area around the sea we crawled out of. Anything beyond that and our bones melt into cancer.
astronomy
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