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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Paul Wiegert (U. Western Ontario): finding interstellar meteors is really hard! Lots of meteors are from comets with high-eccentricity orbits, hard to get good enough data to measure meteor pre-impact orbits. There *are* interstellar meteors, just not as many as that Harvard astronomer (who the speaker did not name) seems to think, and none have been conclusively discovered yet.
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I should note that this session (and a at least one other) at #DDA2026 are tributes to Stan Dermott, who wrote the Solar System Dynamics bible, and taught a LOT of students.
I guess I have a 1-degree-removed connection here? The postdoc I first worked with, Beth Holmes, who taught me a lot, when I was a baby undergrad, had just finished her PhD with him. (She died from a heart condition while I was still an undergrad)
Mark Wyatt (U. of Cambridge) talking about dynamical effects of planets on debris disks (I LOVE this stuff). This is true in our own solar system, zodiacal dust is affected by our planets' orbits.
Ooo Fomalhaut, my favourite disk system! The brightness variations in the disk place constraints on the forced eccentricities resulting from unseen planets in the system.
Fom b is a dust cloud, not a planet, which I am incredibly proud I wrote about years ago! Now proven from JWST images!
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Apostolos Christou (Armaugh Obs.) this talk title is hilarious "Larger asteroids stay sober, smaller asteroids get drunk"
Wow what a cartoon!
Small asteroids end up with gaussian distributions around the family centre.
@sundogplanets Makes me think of the Douglas Adams line:
"You won't like it. It's a bit like being drunk."
"What's wrong with being drunk?"
"Ever ask a glass of water?"
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Mark Wyatt (U. of Cambridge) talking about dynamical effects of planets on debris disks (I LOVE this stuff). This is true in our own solar system, zodiacal dust is affected by our planets' orbits.
Ooo Fomalhaut, my favourite disk system! The brightness variations in the disk place constraints on the forced eccentricities resulting from unseen planets in the system.
Fom b is a dust cloud, not a planet, which I am incredibly proud I wrote about years ago! Now proven from JWST images!
J.-C. Liou (NASA Chief Scientist for Orbital Debris!!) Overview of his career work: started with work on zodiacal dust dynamics, with PR drag and resonances. Showed how outer asteroid belt is depleted by Jupiter MMR sweeping. Then dynamics of cometary dust collected from high altitude aircraft, and Kuiper Belt dust structures.
Now works on distribution of human-made debris pieces in orbit. Now at point where collisions dominate debris creation. Active removal required for long-term.
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Mark Wyatt (U. of Cambridge) talking about dynamical effects of planets on debris disks (I LOVE this stuff). This is true in our own solar system, zodiacal dust is affected by our planets' orbits.
Ooo Fomalhaut, my favourite disk system! The brightness variations in the disk place constraints on the forced eccentricities resulting from unseen planets in the system.
Fom b is a dust cloud, not a planet, which I am incredibly proud I wrote about years ago! Now proven from JWST images!
@sundogplanets This is unbelievably dumb, but perhaps you will enjoy this moronic 1997 punk earworm "Fomalhaut" from Kansas band Danger Bob.
https://www.youtube.com/watch?v=9ynTun5ePAo -
J.-C. Liou (NASA Chief Scientist for Orbital Debris!!) Overview of his career work: started with work on zodiacal dust dynamics, with PR drag and resonances. Showed how outer asteroid belt is depleted by Jupiter MMR sweeping. Then dynamics of cometary dust collected from high altitude aircraft, and Kuiper Belt dust structures.
Now works on distribution of human-made debris pieces in orbit. Now at point where collisions dominate debris creation. Active removal required for long-term.
Ashley Espy Kehoe (Embry-Riddle Aeronautical University)
Recurring theme for Stan Dermott memorial talks: plots are IMPORTANT! (totally agree) So here's a beautiful plot she showed from 1986, that shows how dust bands are created in Solar System (orbital caustics!)
Dust bands tell us about asteroid collisional families. Takes millions of years for full band to form, partial bands give timescales since major collisions, COOL. Dust band structure was confirmed by WISE data.
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Ashley Espy Kehoe (Embry-Riddle Aeronautical University)
Recurring theme for Stan Dermott memorial talks: plots are IMPORTANT! (totally agree) So here's a beautiful plot she showed from 1986, that shows how dust bands are created in Solar System (orbital caustics!)
Dust bands tell us about asteroid collisional families. Takes millions of years for full band to form, partial bands give timescales since major collisions, COOL. Dust band structure was confirmed by WISE data.
Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026
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Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026
@sundogplanets Maybe it’s not too late for me then 🥹.
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Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026
@sundogplanets
Rock . . . Star . . . Gazer?
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Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026
@sundogplanets
Guitarist of the stars.
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Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026
Mark Dodici (U. of Toronto): looking at eclipsing compact triple star systems (two stars orbiting each other, with a third orbiting the inner two). Outer orbits are very circular in observed systems, must be circularized by tides, will shrink inner orbit. Uses Reboundx to simulate this, helps to hone in on tidal Q parameter. So far, not getting useful results, all outside observations. Still working on it, need better tidal model.
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Mark Dodici (U. of Toronto): looking at eclipsing compact triple star systems (two stars orbiting each other, with a third orbiting the inner two). Outer orbits are very circular in observed systems, must be circularized by tides, will shrink inner orbit. Uses Reboundx to simulate this, helps to hone in on tidal Q parameter. So far, not getting useful results, all outside observations. Still working on it, need better tidal model.
Ygal Klein (Princeton) looking at extreme cases of triple systems. Wacky orbits happen! One problem is that as e->1 (super eccentric) precession starts to do weird things and doesn't necessarily match analytics.
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Ygal Klein (Princeton) looking at extreme cases of triple systems. Wacky orbits happen! One problem is that as e->1 (super eccentric) precession starts to do weird things and doesn't necessarily match analytics.
@sundogplanets Only orthogonally related: behavior in X conditions not matching Y Expected Analytics causes hockey fans heads to explode.
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Ygal Klein (Princeton) looking at extreme cases of triple systems. Wacky orbits happen! One problem is that as e->1 (super eccentric) precession starts to do weird things and doesn't necessarily match analytics.
Seth Jacobson (Michigan State U.) hierarchical triple planetesimal systems should be made during streaming instability for planet formation. Kuiper Belt binaries match predictions from streaming instability well, and there is 1 known hierarchical triples and 2 more candidates.
pkdgrav package good for simulating this, making predictions about what systems we should find in Kuiper Belt at higher resolution: 5% of simulated systems are triples.
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Seth Jacobson (Michigan State U.) hierarchical triple planetesimal systems should be made during streaming instability for planet formation. Kuiper Belt binaries match predictions from streaming instability well, and there is 1 known hierarchical triples and 2 more candidates.
pkdgrav package good for simulating this, making predictions about what systems we should find in Kuiper Belt at higher resolution: 5% of simulated systems are triples.
Sarah Millholland (MIT) Prize lecture, which I missed the first few minutes of. Tides are important to explain exoplanets we see.
Super puffs! Some exoplanets are less dense than styrofoam! One possible explanation is tidal heating. Planets misaligned with their stars' spin axis are puffier. Weird.
Realistic exoplanet tides now included in a Reboundx package.
Obliquities also important for tidal migration. Cassini states invoked!
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Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026
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Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026
@sundogplanets i am loving your summary of these presentations. thank you.
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Great way to end the session with a shout-out to Brian May, who started his PhD, took a decades-long break to be a rock star, then finished his PhD, on zodiacal dust, with some help from Stan Dermott. #DDA2026
@sundogplanets can’t love that guy enough, he’s SO my hero
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Sarah Millholland (MIT) Prize lecture, which I missed the first few minutes of. Tides are important to explain exoplanets we see.
Super puffs! Some exoplanets are less dense than styrofoam! One possible explanation is tidal heating. Planets misaligned with their stars' spin axis are puffier. Weird.
Realistic exoplanet tides now included in a Reboundx package.
Obliquities also important for tidal migration. Cassini states invoked!
Time for the outer Solar System! The best dynamics!
Nate Kaib (PSI) talking about dynamically new comets (a>10,000AU), talking about pericenter position relative to node, hard to match sims to observations.
There was a star, HD 7977, that passed within 4000-24,000AU from the sun 2.5 million years ago. This would have perturbed lots of comet orbits, simulations with star passes at 6000-10,000AU match current observations much better. We are still living through a comet shower! Cool!
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Time for the outer Solar System! The best dynamics!
Nate Kaib (PSI) talking about dynamically new comets (a>10,000AU), talking about pericenter position relative to node, hard to match sims to observations.
There was a star, HD 7977, that passed within 4000-24,000AU from the sun 2.5 million years ago. This would have perturbed lots of comet orbits, simulations with star passes at 6000-10,000AU match current observations much better. We are still living through a comet shower! Cool!
This means yesterday in the neighborhood
