Questions tagged [planetary-formation]
Questions about the processes, theories and evidence for the formation of planetary bodies.
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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-...
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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 "...
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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 (...
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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 ...
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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 ...
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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?
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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?
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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 ...
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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-...
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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 ...
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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, ...
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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 ...
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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 (...
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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, ...
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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 ...
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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, ...
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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 ...
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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 ...
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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?
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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, ...
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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 ...
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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 ...
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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-...
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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 ...
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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%
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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'...
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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 ...
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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 ...
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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 ...
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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?&...
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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 ...
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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)...
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Feasibility of Grand Tack Hypothesis
Something I've been wondering lately is how much the grand tack hypothesis stands up to present scrutiny. While the grand tack proposes that Jupiter and Saturn were caught in a 3:2 mean-motion ...
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Why do the solar system planets go rock-gas-ice instead of rock-ice-gas when moving away from the sun?
The sun and the solar wind seem to do a good job of fractionating lighter materials to the outer solar system and leaving heavier materials in the inner solar system. So we end up with rocky/metallic ...
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Why are most discovered exoplanets heavier than Earth?
Looking at all discovered exoplanets (4393 exoplanets), I found than only 17 of them (less than one percent!) have masses less or equal to Earth's mass. Why so?
Is it because it is very difficult to ...
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What is the YORP effect exactly? Is it just the non-central component of the Yarkovsky effect?
This answer to Where have all the Vulcanoids gone? links to the aptly-titled The YORP Effect Can Efficiently Destroy 100 Kilometer Planetesimals At The Inner Edge Of The Solar System which says in ...
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Where have all the Vulcanoids gone?
This answer to Does anything orbit the Sun faster than Mercury? explains that while Vulcanoid asteroids may have been plentiful in the past, large ones have currently been ruled out though smaller ...
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Why isn't the moon's surface made of mini craters?
I thought that the millions of mini rocks that hit the moon would cause it to be entirely cratered and not flat.
Why is the moon not like this:
why aren't craters visible in the footprint photo?
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Life cycle of a gas planet?
I am interested in learning more about the (simplified) life cycle of gas planets which are not brown dwarfs (meaning less than 13 Jupiter masses). It obviously starts off with their creation within a ...
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Can we make reliable models to estimate what the angular momentum was in preplanetary stellar disks?
I have recently become aware of how important the angular momentum of a preplanetary disc may have been in determining what type of a planetary system a star may have. We are able to measure the spin ...
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