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Comment by rendall | Hacker News Reader

Would someone who has knowledge in this domain be willing to explain the significance of this? To me, it just describes 2 protoplanets in a dust disk, but I'm sure it has some importance to astronomers in order to hit front page of HN

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Many circumstellar disks have been detected, but this is the first unambiguous detection of a circumplanetary disk. This is believed to be material swirling around a protoplanet, accreting on to it, and perhaps, forming moons. The actual processes of how planets form out of protoplanetary disks are still not well understood, so observations like this will help narrow things down. Quite impressive that they were able to resolve it with ALMA.

No expertise in the matter, but I assume the question is how our solar system formed with gas giants in the outer orbits and rocky planets in the habitable zone and how common this might be around other stars. The final paragraph of the conclusion has some hints.

I am particularly interested in why we are on a planet that is so rich in phosphorus and the final phrase about "delivery of chemically enriched material to planetary atmospheres" is a real tease.

The Bae et al paper linked in that paragraph (https://iopscience.iop.org/article/10.3847/2041-8213/ab46b0) (note Bae is cited second on OP paper) actually has quite a bit more to do with the way planets settle into orbits, based on study of this same system. As a fellow layman I haven't read it in detail but it looks fascinating, will check it out later.

These are really interesting papers and full of pics and diagrams, although the math is beyond me.

This might help: https://en.wikipedia.org/wiki/Grand_tack_hypothesis

From a layperson's perspective (I am not an astronomer at all), it sounds like they found 2 Saturn-like planets in the making. They're still forming from their dust disks. That in itself is cool.

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