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'Fingerprints' inside the Sun could reveal if it once swallowed a planet

ras.ac.uk

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Re: 'Fingerprints' inside the Sun could reveal if it once swallowed a planet

#31

Post by birdsongs »

spectraldrift wrote: post #28

This might just be me, but I find metaphors like ''Fingerprints' inside the Sun' harder to read than the title of the original paper, which is probably what should be linked here per HN submission guidelines: > Planetary engulfment as a solution to solar-model discrepancies and its implications for planetary systems https://doi.org/10.1093/mnras/stag1527 For the press release, something like The Real Sun and Its Simu…

There's been a lot of changed titles recently, and it is quite annoying. I feel like that used to get corrected.

Re: 'Fingerprints' inside the Sun could reveal if it once swallowed a planet

#32

Post by frutiger »

monster_truck wrote: post #15
omnicognate wrote: post #5

Earlier quoted context omitted.

> Researchers also found that such a world could survive its passage through the Sun's outer layers while losing very little mass, which suggests that planets may leave detectable fingerprints inside their host stars long after they have disappeared. So I guess the large size would have permitted it to smuggle stuff into the core that would have just vaporised in the corona if carried by many smaller objects?

Sounds reasonable to me. But also what the fuck happens to the core of such a planet when that happens? We aren't actually sure what gave our core the spin it has, right? I'm not fully awake yet but I think it's plain where I'm going with this.

> We aren't actually sure what gave our core the spin it has, right?

We are, it’s from the conservation of angular momentum. The material that made our planet also had a non-zero angular momentum.

Re: 'Fingerprints' inside the Sun could reveal if it once swallowed a planet

#34

Post by ahazred8ta »

hydrogen7800 wrote: post #11
A_D_E_P_T wrote: post #2

> Their results favour a scenario in which the young Sun engulfed a super-Earth around 5–10 times the mass of Earth Given the state of the early solar system, it would be surprising if the Sun didn't swallow a lot of metallic and carbonaceous rocks and pebbles. But it seems unclear to me how the researchers would distinguish between one super-Earth and >10^10 smaller rocks? Chemically I feel the two would be largely…

>But it seems unclear to me how the researchers would distinguish between one super-Earth and >10^10 smaller rocks? I have a similar feeling when life on earth is suggested to be "alien", arriving via debris in the solar system as the earth formed. Isn't everything in the solar system coalesced from the same debris?

Same thing with people who naively believe that amino acids can only be formed in space and can only be brought to Earth in asteroids, as opposed to forming *ON* Earth.

Our current best guess is a geothermal vent in a high phosphorus 'soda lake' like the one in Canada. https://www.science.org/content/article/unusual-soda-lakes-m...

Re: 'Fingerprints' inside the Sun could reveal if it once swallowed a planet

#35

Post by jjk166 »

hydrogen7800 wrote: post #11
A_D_E_P_T wrote: post #2

> Their results favour a scenario in which the young Sun engulfed a super-Earth around 5–10 times the mass of Earth Given the state of the early solar system, it would be surprising if the Sun didn't swallow a lot of metallic and carbonaceous rocks and pebbles. But it seems unclear to me how the researchers would distinguish between one super-Earth and >10^10 smaller rocks? Chemically I feel the two would be largely…

>But it seems unclear to me how the researchers would distinguish between one super-Earth and >10^10 smaller rocks? I have a similar feeling when life on earth is suggested to be "alien", arriving via debris in the solar system as the earth formed. Isn't everything in the solar system coalesced from the same debris?

Well if we found current or fossil life with a common ancestor on other bodies it would certainly demonstrate that it arrived via debris; whereas if we find life with no common ancestor or find no evidence of life at all that would reject the hypothesis. It wouldn't necessarily answer which body was the original birthplace, but for the purposes of modelling, whether life happened to start here is a much less impactful question than whether life had to start here. If all life here started here, then life had to develop quickly; if we could potentially descend from stuff in the pre-solar system debris field that could add billions of years to the clock, and makes interstellar panspermia highly plausible.

Re: 'Fingerprints' inside the Sun could reveal if it once swallowed a planet

#36

Post by fainpul »

About that artist's impression with the blue spiral: wouldn't any planet or other object do one of these things:

- approach and hit directly, without spiraling

- approach, make a close fly-by and fly off into deep space again

- be in a steady, eliptical orbit

My knowledge is basically that of a Kerbal.

Re: 'Fingerprints' inside the Sun could reveal if it once swallowed a planet

#38

Post by gus_massa »

regularfry wrote: post #22

Has someone got a quick explainer for why adding a planet would result in less lithium? Is it just that a super-earth would be big enough and have so little lithium that it would measurably water down the other elements?

Neither an astrophysics. I skimmed the paper. IIUC the collision with the planet mixed internal layers of the Sun and a lot of the Lithium went to the core and got fussed with Hydrogen.

PS: The paper says that that actual A(Li)=1.1 instead of the expected A(Li)=3.3. I needed a lot of search to understand it until Gemini kindly liked this page. https://astronomy.stackexchange.com/questions/61814/what-do-...

A(Li)=1.1 means the Li/H ratio is 10^(-10.9) = 10^(-8.9)%

A(Li)=3.3 means the Li/H ratio is 10^(-9.7) = 10^(-7.7)%

Re: 'Fingerprints' inside the Sun could reveal if it once swallowed a planet

#39

Post by wongarsu »

fainpul wrote: post #36

About that artist's impression with the blue spiral: wouldn't any planet or other object do one of these things: - approach and hit directly, without spiraling - approach, make a close fly-by and fly off into deep space again - be in a steady, eliptical orbit My knowledge is basically that of a Kerbal.

There are obviously many things KSP's patched conics approximation can't account for, like lagrange points or how orbits often get twisted around over time, or how the small effects from all the other solar bodies add up to be significant over time.

The simplest thing that comes to mind here is that KSP simulates a mature solar system, where space is mostly empty. This event happens in an early solar system, where there's lots of stuff everywhere. Running into stuff can steal some of the planet's momentum, causing it to fall deeper, causing it to run into more stuff

But planetary migration can be a lot more complicated than that. [1] has an overview. You might also enjoy the Grand Tack hypothesis [2] which involves early Jupiter spiraling into the inner solar system until around the orbit of current-day Mars, before eventually reversing course and getting to its current orbit further out

1: https://en.wikipedia.org/wiki/Planetary_migration

2: https://en.wikipedia.org/wiki/Grand_tack_hypothesis

Re: 'Fingerprints' inside the Sun could reveal if it once swallowed a planet

#40

Post by monster_truck »

frutiger wrote: post #32
monster_truck wrote: post #15

Earlier quoted context omitted.

Sounds reasonable to me. But also what the fuck happens to the core of such a planet when that happens? We aren't actually sure what gave our core the spin it has, right? I'm not fully awake yet but I think it's plain where I'm going with this.

> We aren't actually sure what gave our core the spin it has, right? We are, it’s from the conservation of angular momentum. The material that made our planet also had a non-zero angular momentum.

No we aren't. That's a theory that barely fits the lower bound of what we estimate the spin of the core to be
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