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Questions tagged [planetary-formation]

Questions about the processes, theories and evidence for the formation of planetary bodies.

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How can a planet's perihelion be raised during migration?

I've been reading about the hypothetical Planet Nine, but there are two passages in the Wikipedia article that puzzle me: Several possible origins for Planet Nine have been examined, including its ...
John Dallman's user avatar
2 votes
2 answers
94 views

What stops terrestrial planets from becoming watery gas giants with water vapour atmospheres?

How come planets beyond the frost line form with ice cores but terrestrial planets didn't accrete anywhere near as much water vapour? The way I understand accretion to work, planets form out of ...
Ale Kid's user avatar
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9 votes
1 answer
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Had Earth lost the Moon early, would we be able to determine it once had a companion?

Despite the Solar System looking quite stable, clockwork-like on human timescales, to such a degree the movement of its members is used to track time and make calendars since antiquity, it is pretty ...
ksousa's user avatar
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3 votes
0 answers
110 views

How well are planetary formation models (e.g., determining $\mathrm{\dot{M}_{planet}}$) understood in 2024?

I know that planets can form through accretion, bulging up from $0$ to their final mass $\mathrm{M_{planet}}$ at $\mathrm{M}(t_f)$. I know that when studying Planetary formation and migration theories,...
nuwe's user avatar
  • 771
3 votes
1 answer
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About the formation of ice giants and gas giants

I asked this previously in Worldbuilding stack exchange, and they recommended that I take it here. How far out from a star (lets just say one identical to our sun, for simplicities sake) where can gas ...
DanceroftheStars's user avatar
3 votes
1 answer
157 views

How much mass did the Late Heavy Bombardment add to Mars?

How much mass was deposited on a terrestrial planet during the Late Heavy Bombardment (LHB)? Is it possible to estimate a reasonable interval, specifically, for Mars? Could the mass addition to Mars ...
Michael_1812's user avatar
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0 votes
0 answers
33 views

How to plot different curves in the same polar cordinates in matplotlib?

I tried to plot the paths of particle of different sizes in the same polar coordinate using the code given below using matplotlib. somewhat like this: Instead I got this plot: while the path for ...
Lunthang Peter's user avatar
-3 votes
2 answers
216 views

Why is it so difficult to believe that the Sun once had a companion star

If the Sun once had an older companion star that exploded 5 billion years ago it could surely explain many things about the solar system. Such as why so many planets have hot cores that are cooling. ...
Michael Mcgarry's user avatar
0 votes
1 answer
224 views

Why don't scientists believe Earth's surface water came up from the mantle?

I read, periodically, that there is more water trapped in the mantle than there is in the oceans - possibly a lot more. If so, why don't any geologists believe that Earth's surface and near-surface ...
Kurt Hikes's user avatar
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3 votes
2 answers
100 views

How would we tell the difference between low mass objects that formed by direct collapse or in an accretion disk?

In this question about rogue planet/sub brown detection there are a couple of comments about classification of non-stellar, low mass, free floating objects. Part of one of the answers is - Some "...
Futoque's user avatar
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1 answer
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If E.T. alien civilizations exist, won't those exoplanets be almost the age and rate of progress as ours? [closed]

This question is posed also as a mini theory, although I am really asking if someone knows how some parts of our universe would be far-more advanced if "everything" started at the same time (...
Dr. Deshando's user avatar
-4 votes
1 answer
81 views

Did liquid helium help the solar system to form by cooling the nebula that collapsed to form it?

Was the gas cloud that collapsed to form the solar system cooled by liquid helium at some point in time? I ask because the Cosmic microwave background had a temperature around 3K when the solar system ...
user avatar
1 vote
0 answers
75 views

What do chthonian planets look like?

Obviously, a chthonian is going to be hot, but what colours could it have? What would the surface composition be? Would it keep patterns from the gas-bands it used to have, or would those have been ...
Kazon's user avatar
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3 votes
1 answer
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How accurate is the Sudarsky Scale today?

How accurate is the Sudarsky scale of gas-giant classification today? Do the different classes still exist, and look roughly the same?
Kazon's user avatar
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0 answers
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Why do planets in our solar system have different chemical compositions? [duplicate]

Was this caused by turbulence in the disc that went on to form the solar system or was the disc itself just endowed with an uneven distribution of elements?
user avatar
5 votes
1 answer
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"And in some cases, a (free floating) planet (FFP) can form on its own outside of any solar system." Cool! But what are those cases?

The April 2, 2023 Inverse article 9 Years Ago, Astronomers Found Two Rogue Planets — But They Didn’t Realize It Until Now says: Planets are typically part of a planetary system and are ...
uhoh's user avatar
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3 votes
1 answer
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Protoplanetary disk luminosity - looking for a sanity check please

I've been told to "consider an Earth-mass of interplanetary grains (roughly spherical with a radius of a few microns) in a protoplanetary disk. Let the particles be in a torus with a cross-...
Chris M's user avatar
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1 vote
0 answers
49 views

Would gravitational stratification deter carbon-based life on large rocky planets?

Most of Earth's heavy elements are concentrated in its deepest layers, as they're denser than the surrounding silicates and sink to the core. If its overall gravitational pull were substantially ...
Thoth's user avatar
  • 181
3 votes
1 answer
198 views

Orbital Stability of a Double Planet System

I recently found an article claiming a double planet system needs to be at least .5 AU from its parent star to be stable for billions of years. It was specifically talking about two same-mass bodies, ...
Thoth's user avatar
  • 181
2 votes
1 answer
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How are the products of stellar nucleosynthesis sorted as found in planets?

Stellar nucleosynthesis is responsible for creating the elements heavier than lithium (except perhaps some of the heaviest that might result from neutron star collisions). Eventually, the star goes ...
Moshe Feder's user avatar
4 votes
2 answers
136 views

Could a planet have a massive crater without collapsing due to gravity / other factors?

A severely destroyed planet is a popular trope in media. Here are a few examples from fiction with pictures (spoiler warning). A crater with a diameter 1/3rd the size of the planet itself: Earth (...
Omboam's user avatar
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1 vote
0 answers
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Has anybody measured the mass density profile $\Sigma = \Sigma (r)$ of a protoplanetary disk? (when $r<1$ AU)

I've been trying to find research articles where the mass density distribution $\mathrm{\Sigma = \Sigma(r)}$ is determined for protoplanetary disks, when $r<1$ au. For instance: Here A. Miotello, ...
nuwe's user avatar
  • 771
11 votes
3 answers
4k views

At what point in history was the idea of planets being spit out by the sun abandoned?

For context, at some point during the 20th century (and maybe earlier as well), the most popular planet formation theory and the one that was taught at (at least some) schools was the theory that the ...
Justin T's user avatar
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6 votes
1 answer
904 views

Why didn't Kessler Syndrome prevent planet formation?

In 1978, Donald Kessler proposed that space pollution in orbit around the Earth could enter a collisional cascading state. This means debris would collide with satellites, generating more debris, ...
Connor Garcia's user avatar
  • 16.3k
4 votes
3 answers
3k views

Why do most dwarf planets have mass comparable to moon?

It was quite interesting to spot that most dwarf planets have masses close to that of our moon (if we let an error to fluctuate within two orders of magnitude). Why it is so? Is there any common ...
Agnius Vasiliauskas's user avatar
5 votes
0 answers
52 views

Extract surface density profile from a temperature profile?

I have a protoplanetary disk model which outputs a temperature vs. radius profile, based on radiative transfer. Looks something like this... One of the inputs to the model is the surface density ...
lucas's user avatar
  • 1,386
0 votes
1 answer
88 views

Can a destroyed earth reform into another habitable planet?

Let's say a planet-sized object collide with earth, disintegrate it, then reform at the same orbit as earth. Will it eventually formed into a habitable, life-supporting planet with living organism?
actomobile's user avatar
18 votes
3 answers
2k views

How is asteroidal rock formed?

So when planets form, dust from the protoplanetary nebula gets collected by gravity and then heated and reformed under pressure until it forms dense masses of stuff which we call rock. However, ...
David Given's user avatar
1 vote
1 answer
639 views

What is a Keplerian shear

I was reading an article on Gas Giants and how some form close to their host star. One line in the article says: A region of the proto-planetary disk will be susceptible to gravitational instability ...
WDUK's user avatar
  • 415
1 vote
2 answers
194 views

Is the gas in a planet forming disk around a star comparable in density to an atmosphere?

If you were standing on a planetesimal in the planet forming disk of a new solar system (or our own, billions of years ago), would you be able to feel "interplanetary wind"? Would it be ...
Dennis's user avatar
  • 121
4 votes
0 answers
170 views

Could or has a Ninth planet ever be "formed" in our solar system?

As I get along with the answers in my previous question, that planet formation depends on accumulation of planetesimals. So is there any chance that a planet nine would form or any of the Trans-...
Kavin Ishwaran's user avatar
3 votes
1 answer
211 views

The reason for an exoplanet density increase of planets closer to a star

From the NASA exoplanet archive system it can be seen that in the range of $0.02-0.06~\text{AU}$ distance an exoplanet is to its star, as distance drops down, the planet density increases linearly: A ...
Agnius Vasiliauskas's user avatar
10 votes
3 answers
864 views

Why is the composition of the sun so distinct from that of earth?

Given that the sun is – in astronomical distances – quite close to the earth, why are the two composed of such distinctly different substances? Sun Composition Hydrogen 74.9% Helium 23.8% Oxygen ~1% ...
Cory Klein's user avatar
1 vote
1 answer
57 views

Envelope Enrichment?

While I was researching about planet formation, I repeatedly came across the term envelope enrichment. What does this mean? I searched it up and looked at many websites, but no helpful definitions ...
asterism's user avatar
2 votes
0 answers
80 views

Farthest observed protoplanetary disk observed at radio frequencies? Catalog

This could be a naive question or maybe too easy to solve (I do not really know!). Brief context: I'm interested in a certain planetary system at $d \sim 300 \, \mathrm{pc}$. It would be really nice ...
nuwe's user avatar
  • 771
11 votes
1 answer
385 views

How do rocky objects between 1cm and 1m accrete to form planetesimals?

I am having a hard time gaining an intuitive understanding of some of the middle stages of planetary formation from a protoplanetary accretion disk. I understand that microscopic dust particles may ...
user438383's user avatar
9 votes
1 answer
231 views

What's the expected distribution of planet masses in a given system?

Given that the mass of a planet at a given orbital distance r is dependent on the protoplanetary material in the neighborhood of r at the time of formation (assuming no planetary migration), what ...
Anthony Khodanian's user avatar
5 votes
2 answers
444 views

How do scientists know that Earth used to spin much more rapidly?

News has just been released all over my news feeds about how paleontologists now believe that early photosynthetic organisms became much more efficient at producing oxygen after the Earth started to ...
Kurt Hikes's user avatar
  • 5,177
4 votes
1 answer
360 views

Where will the frost line be when the Sun becomes a red giant and what effect will it have on the solar system?

I understand the frost line is currently about 5.2 AU and earlier in the solar systems formation was 2.7 AU. But when the Sun becomes a red giant the frost line should move outward. I understand the ...
Brooks Nelson's user avatar
25 votes
2 answers
2k views

Intuitive explanation of the source of energy that cause Jupiter and Saturn to migrate outward in the Grand Tack Hypothesis?

The Grand Tack Hypothesis states that Jupiter first migrate inward, but it was caught up by the faster inward migration of Saturn, and when the two planets reached 3:2 mean-motion resonance they ...
Cloudy's user avatar
  • 373
0 votes
1 answer
81 views

Can the pebbles growth model be applied to the rotations of planetary systems? [duplicate]

I've just read the University of Amsterdam 2019 News item Pebbles determine the direction in which planets rotate (which links to R.G.Visser et al (2020) Spinning up planetary bodies by pebble ...
Deschele Schilder's user avatar
3 votes
2 answers
137 views

Spin-down of gas-giants during formation

In the paper https://arxiv.org/abs/1712.00457 about rotation rates of gas giants it says: "owing to accumulation of angular momentum stored in the source material, a planetary mass object should ...
sno's user avatar
  • 1,455
2 votes
1 answer
338 views

What does it mean for a planet to have an "icy" core?

My understanding of the physics of planets leans heavily on my understanding of the physics of stars - of course there are important differences. One important difference that I've found is the nature ...
Daddy Kropotkin's user avatar
1 vote
1 answer
75 views

What is the meaning of grain opacity and why does it affect the formation time of gas giants?

While doing research for my presentation on the formation of gas giants, more specifically the "core-accretion model", I have been stumbling across the term "grain opacity" and don'...
Julian Saling's user avatar
2 votes
1 answer
88 views

Are accretion disks the only way stellar planetary systems form?

The accepted theory for the formation of our Solar System is from an accretion disk. A molecular cloud is thought to have collapsed under its own gravity and formed a disk. Most of the matter in the ...
Connor Garcia's user avatar
  • 16.3k
5 votes
1 answer
114 views

Assuming a hypothetical system without gas but only solid rocks, how big of a planet can form through the coalescing of these rocks?

I have heard that gas giants are primarily huge solid bodies like regular rocky planets that exponentially gained more and more gas in their atmosphere through their increase in mass which they use ...
Hash's user avatar
  • 503
0 votes
1 answer
124 views

River-like artifact in perseverance rover's photo of Mars

Good to know that perseverance rover has touched the surface of Mars finally. We will have nice new opportunity window for exploring our closest "friendly" planet of solar system. Here's one ...
Agnius Vasiliauskas's user avatar
6 votes
1 answer
1k views

Why is Mercury's Density So Low?

I know the title sounds odd. You might be thinking "Doesn't Mercury have the highest uncompressed density of any terrestrial planet? Much higher than a planet its size normally should have?&...
Xi-K's user avatar
  • 403
1 vote
0 answers
38 views

Can we see traces of exo-moon formation?

Our Moon was likely formed by the collision of a Mars-size object with the Earth soon after the planets first formed. Would traces of such an event be detectable by observing the protoplanetary disc ...
usernumber's user avatar
  • 17.6k
3 votes
2 answers
200 views

After a supernova, why don't new stars coalesce with higher heavier element content?

May be a beginner's question but I couldn't find the answer anywhere. Given a supernova event and the cloud left by it, why does a new star coalesce with a disproportionally higher hydrogen(and helium)...
Matheus Simon's user avatar