Between my normal meetings and writing, I'm watching a few talks at the American Astronomical Society's (AAS) Division for Dynamical Astronomy (DDA) annual meeting this week.
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Konstantin Batygin (Caltech): most common planets are super-Earths on very short orbits. How do they not fall into their star? How do they pick which resonance to lock in to? (Bonus points for joke about a system with a 6:7 resonance for everyone with middle-school-aged kids)
Giant equation in a confetti explosion (this guy likes giving talks). Shows that 6:7 resonance requires planets to form simultaneously at 1-3AU: the "planet factory ring"
@sundogplanets Special thanks for the 6-7.
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Between my normal meetings and writing, I'm watching a few talks at the American Astronomical Society's (AAS) Division for Dynamical Astronomy (DDA) annual meeting this week. They have this fantastic option where you pay US$10 and you can watch all the talks at the meeting. I'll try to share summaries of a few highlights using #DDA2026
@sundogplanets thank you! I like reading these little summaries, even if I don't totally understand the science.
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Konstantin Batygin (Caltech): most common planets are super-Earths on very short orbits. How do they not fall into their star? How do they pick which resonance to lock in to? (Bonus points for joke about a system with a 6:7 resonance for everyone with middle-school-aged kids)
Giant equation in a confetti explosion (this guy likes giving talks). Shows that 6:7 resonance requires planets to form simultaneously at 1-3AU: the "planet factory ring"
@sundogplanets This made me look up again a remarkable series of videos on formation of this solar system by Sean Raymond and Alessandro Morbidelli. They call it "MOJO" or Modeling the Origin of Jovian Planets. I've never seen anything like it.
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@sundogplanets Special thanks for the 6-7.
It is 6-11 that we really fear
https://www.tumblr.com/teledyn/816002228085194752/the-tumblr-prophecy?source=share -
Konstantin Batygin (Caltech): most common planets are super-Earths on very short orbits. How do they not fall into their star? How do they pick which resonance to lock in to? (Bonus points for joke about a system with a 6:7 resonance for everyone with middle-school-aged kids)
Giant equation in a confetti explosion (this guy likes giving talks). Shows that 6:7 resonance requires planets to form simultaneously at 1-3AU: the "planet factory ring"
@sundogplanets
Would 1 AU be a "very short orbit"?Added in edit: (I guess so, for "super-Earths". Is my (very amateur) thinking kinda sorta somewhat right, or am I missing the whole point?)
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Konstantin Batygin (Caltech): most common planets are super-Earths on very short orbits. How do they not fall into their star? How do they pick which resonance to lock in to? (Bonus points for joke about a system with a 6:7 resonance for everyone with middle-school-aged kids)
Giant equation in a confetti explosion (this guy likes giving talks). Shows that 6:7 resonance requires planets to form simultaneously at 1-3AU: the "planet factory ring"
Gabriel Teixeira Guimaraes (National Obs of Japan) more REBOUND sims! Aligned pericenters are important for stability, but absolutely required for higher eccentricity systems.
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Gabriel Teixeira Guimaraes (National Obs of Japan) more REBOUND sims! Aligned pericenters are important for stability, but absolutely required for higher eccentricity systems.
As part of the CV-rejiggering for academic stuff that I previously complained about, I also need to update my academic website (which is embarrassingly simple, but at least I didn't write it in 1999 and it doesn't have a dancing-linux-penguin-gif like Some Other Academics). Will be trying to do that while listening to the next set of #DDA2026 talks
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As part of the CV-rejiggering for academic stuff that I previously complained about, I also need to update my academic website (which is embarrassingly simple, but at least I didn't write it in 1999 and it doesn't have a dancing-linux-penguin-gif like Some Other Academics). Will be trying to do that while listening to the next set of #DDA2026 talks
@sundogplanets you definitely need the under construction sign with a spinning light and the dog running across the bottom. Oh and marquee text.
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@sundogplanets
Would 1 AU be a "very short orbit"?Added in edit: (I guess so, for "super-Earths". Is my (very amateur) thinking kinda sorta somewhat right, or am I missing the whole point?)
@oldclumsy_nowmad it totally depends on the context of who you're talking to! This presentation considered that short.
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As part of the CV-rejiggering for academic stuff that I previously complained about, I also need to update my academic website (which is embarrassingly simple, but at least I didn't write it in 1999 and it doesn't have a dancing-linux-penguin-gif like Some Other Academics). Will be trying to do that while listening to the next set of #DDA2026 talks
@sundogplanets KIS websites should be celebrated not frowned upon or "augmented".
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As part of the CV-rejiggering for academic stuff that I previously complained about, I also need to update my academic website (which is embarrassingly simple, but at least I didn't write it in 1999 and it doesn't have a dancing-linux-penguin-gif like Some Other Academics). Will be trying to do that while listening to the next set of #DDA2026 talks
Kaustub Anand (Purdue). Did Mars' moons form from capturing asteroids or a giant impact? Giant impact would make a ring, would cycle with moon - but previous studies ignore collisions within disk. They don't use REBOUND (weird!) they use Swiftest.
Sesquinary catastrophe is the best name! I guess that is caused by moon debris ring re-impacting and destroying the moon. Oo Yarkovsky-Schach effect invoked, constrains ring, helps avoid castrophe
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Kaustub Anand (Purdue). Did Mars' moons form from capturing asteroids or a giant impact? Giant impact would make a ring, would cycle with moon - but previous studies ignore collisions within disk. They don't use REBOUND (weird!) they use Swiftest.
Sesquinary catastrophe is the best name! I guess that is caused by moon debris ring re-impacting and destroying the moon. Oo Yarkovsky-Schach effect invoked, constrains ring, helps avoid castrophe
Thea Faridani (U. of Rochester) What if we had another Moon closer-in shortly after Moon formation? Impact-migrate-moonlet-merge. Back to REBOUND again! Early results: mutual inclinations and obliquities are really important for keeping moonlets around.
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Peas-in-a-pod exoplanet systems (multiple similar-mass planets closely packed) maybe follow the co-accretion pattern? Simulations with gas migration show a characteristic mass for surviving planets, that doesn't depend strongly on stellar metallicity. Cool!
This sounds like a fun sci-fi setting. Multiple habitable planets that are relatively easy to travel between, which evolved separately.
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Thea Faridani (U. of Rochester) What if we had another Moon closer-in shortly after Moon formation? Impact-migrate-moonlet-merge. Back to REBOUND again! Early results: mutual inclinations and obliquities are really important for keeping moonlets around.
Raluca Rufu (SWRI) high angular momentum impact could well-mix Earth's mantle and the moon precursor, but then you have to get rid of excess angular momentum. Dumping that depends on internal thermal evolution of Earth, and its spin. Moon's outward migration speeds up after Earth cools enough to re-solidify, how long solidification takes depends on Earth's atmosphere post-collision.
Evection resonance doesn't seem to remove enough angular momentum.
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Raluca Rufu (SWRI) high angular momentum impact could well-mix Earth's mantle and the moon precursor, but then you have to get rid of excess angular momentum. Dumping that depends on internal thermal evolution of Earth, and its spin. Moon's outward migration speeds up after Earth cools enough to re-solidify, how long solidification takes depends on Earth's atmosphere post-collision.
Evection resonance doesn't seem to remove enough angular momentum.
Helena Buschermohle (Instituto Nacional de Pesquisas Espacias) what happens to moons around circumbinary planets? As planets migrate inwards, Hill sphere gets smaller and moons would become unbound. HAHA she calls stable moons "smoons" and a moon that becomes a planet a "ploonet"
All circumbinary exoplanets discovered so far are gas giants, but maybe moons could be habitable, now that we know some moons survive migration.
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As part of the CV-rejiggering for academic stuff that I previously complained about, I also need to update my academic website (which is embarrassingly simple, but at least I didn't write it in 1999 and it doesn't have a dancing-linux-penguin-gif like Some Other Academics). Will be trying to do that while listening to the next set of #DDA2026 talks
@sundogplanets Sounds to me like you need to add a dancing penguin
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Helena Buschermohle (Instituto Nacional de Pesquisas Espacias) what happens to moons around circumbinary planets? As planets migrate inwards, Hill sphere gets smaller and moons would become unbound. HAHA she calls stable moons "smoons" and a moon that becomes a planet a "ploonet"
All circumbinary exoplanets discovered so far are gas giants, but maybe moons could be habitable, now that we know some moons survive migration.
@sundogplanets Of course with the bizarre world definition of planet forced on us .. if those unbound moons just happen to end up in a clear space, they're planets, otherwise ..
️She's routed around the "planet" quagmire and created her own lovely words to describe this new situation, love it.
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@sundogplanets you definitely need the under construction sign with a spinning light and the dog running across the bottom. Oh and marquee text.
@fullywoolly @sundogplanets good web design <blink>never</blink> dies
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Helena Buschermohle (Instituto Nacional de Pesquisas Espacias) what happens to moons around circumbinary planets? As planets migrate inwards, Hill sphere gets smaller and moons would become unbound. HAHA she calls stable moons "smoons" and a moon that becomes a planet a "ploonet"
All circumbinary exoplanets discovered so far are gas giants, but maybe moons could be habitable, now that we know some moons survive migration.
@sundogplanets Love a ploonet
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Helena Buschermohle (Instituto Nacional de Pesquisas Espacias) what happens to moons around circumbinary planets? As planets migrate inwards, Hill sphere gets smaller and moons would become unbound. HAHA she calls stable moons "smoons" and a moon that becomes a planet a "ploonet"
All circumbinary exoplanets discovered so far are gas giants, but maybe moons could be habitable, now that we know some moons survive migration.
Now it's a prize talk by Sam Hadden (CITA) about resonant planetary systems, and he's PLAYING MUSIC to demonstrate orbits I love this so much (although I have to say it's not working super great over Zoom, sounds drown out the speaker, oh well). Mean-motion resonances function very much like chords! (This is very well explained in this fantastic website, read it all and enjoy: https://www.system-sounds.com/about/)
