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   Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:26 JST Prof. Sam Lawler

   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

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:12 JST Prof. Sam Lawler

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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!

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:13 JST Prof. Sam Lawler

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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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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:13 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:13 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:13 JST Prof. Sam Lawler

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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.

     #DDA2026

     Steve's Place repeated this.
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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:14 JST Prof. Sam Lawler

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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!

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:14 JST Prof. Sam Lawler

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     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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:14 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:15 JST Prof. Sam Lawler

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     Daniel Durda (SWRI): Overview talk. The asteroid belt is a fossilized collisional system - the size distribution (particularly waves in size dist) tells us about the past. Dust production is "spikey": lots right after a big collision.

     Lots of work on Chicxulub impact, where does debris land? (Back into atmosphere, heating it up, burning everything)

     Used Ames gun to smash real meteorites and study dust from them.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:15 JST Prof. Sam Lawler

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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)

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:16 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:17 JST Prof. Sam Lawler

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     David Minton (Purdue): Starts with really cool animation of Moon getting blasted by asteroids! Compares craters to dino footprints. Makes the point that better data (seeing smaller craters) changes the story dramatically

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:17 JST Prof. Sam Lawler

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     Ben Cassese (MPC): here comes the flood of Solar System small body data! Expect 200 million observations per year from Rubin, + 200 million from NEO Surveyor. MPC has to quickly link previous observations into new orbits, this is hard. Will need machine learning to process everything.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:17 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:18 JST Prof. Sam Lawler

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     Oooo he's got a bunch of orbital sonification on his website! https://shadden.github.io/sonification/

     Oooo really neat to hear a chord change during an N-body simulation when stability is lost and a planet swaps to a different resonance.

     Resonant chain migration behaves like masses on springs, says it's like vibrato! Cool.

     "So that's a lot of fun, but so what?" Unstable modes grow or decay depending on how eccentricities are damped.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:18 JST Prof. Sam Lawler

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     Most super earth systems are not resonant (they don't sound so nice), and lots are near-resonant and sound a little out of tune (some sound quite ominous!)

     If you throw a few Plutos in to the system, scattering will disrupt the chain that formed, sometimes leaves them near but not quite in the resonance.

     Ends with a note to Kepler (the astronomer) who thought the planets should be in perfect resonance, if not now, maybe when formed. Cool!

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:18 JST Prof. Sam Lawler

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     Leia Shen & Kavi Dey (Harvey Mudd College) current categorization looking for asteroid dynamical families takes ~30 minutes of computation per asteroid. Vera Rubin observatory will discover 10 million more asteroids. Using machine learning and computationally cheaper asteroid properties to find families. Code is available, but they only gave it as QR code not a link...sigh.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:19 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:19 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:19 JST Prof. Sam Lawler

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     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/)

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:20 JST Prof. Sam Lawler

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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

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:20 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:21 JST Prof. Sam Lawler

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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.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:21 JST Prof. Sam Lawler

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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

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:22 JST Prof. Sam Lawler

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     Sacha Gavino (U. Bologna) millions of sims of 3 equal mass earth planets in extremely compact orbits, mapping out 3 body interactions with orbit spacing. Really complex stability structure, depends on initial longitudes of planets. Holy cow that's a complicated map of "the 3-body resonance network", looking at where resonances overlap and chaos happens, and where resonances push planets into higher stability orbital configurations.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:22 JST Prof. Sam Lawler

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     Julia Esposito (Georgia Inst of Tech) looking at planet-planet scattering, uses REBOUND TRACE and Reboundx because need close encounters between planets, long integrations, general relativity, and tides (wow). Cold scattering (distances outside 1AU) is needed to produce hot Jupiters. Made lots of eccentric, aligned, warm Jupiters. Predict warm Jupiters should have nearby companions with >30 degree mutual inclinations

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:22 JST Prof. Sam Lawler

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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"

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:23 JST Prof. Sam Lawler

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     Wen-Han Zhou (U. Tokyo) why do Saturn A and B rings have such sharp inner rings? Can't be explained by moons. Yarkovsky changes spins through absorbtion and re-radiation of light being in different places (due to rotation). Adding in an eclipse, as for a binary system, changes the average force. This gets REALLY complicated for a ring made of particles all eclipsing each other! Calculate using pkdgrav package, including Saturn radiation. Inner edge is sharp, outer edge leaks outwards

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:23 JST Prof. Sam Lawler

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     Yurou Liu (Yale): hot-Jupiter hosting binaries are more eccentric, OR hot Jupiters are preferentially aligned with their binaries. They found this through building a bunch of simulated hot Jupiter systems and letting the Kozai effect change the eccentricities and inclinations and looking at the final distributions

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:23 JST Prof. Sam Lawler

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     Grant Weldon (UCLA): oh I like this talk title "Saving Doomed Planets". Hot Jupiters like to fall into their stars. But mass loss is important - by losing mass some of them end up not falling into their stars. High eccentricity migration can be survived, but sometimes hot Jupiters turn into hot Neptunes.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:24 JST Prof. Sam Lawler

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     Ian Brunton (Caltech) shows that Io and Europa's 2:1 mean-motion resonance can be primordial, but Ganymede's 4:2:1 mean-motion resonance wouldn't have been stable in the primordial disk and would need to fall into place later

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:24 JST Prof. Sam Lawler

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     K. Dabroski (U. Idaho) How did Saturn's rings form? Uses only Chrysalis (a.k.a. proto-Hyperion), Titan, and Saturn's J2 as perturbers in REBOUND https://rebound.hanno-rein.de/ Iapetus is important for getting eccentricities high enough for a collision. More sims needed!

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:24 JST Prof. Sam Lawler

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     Guangyi Zhang (Caltech) Moon-planet tidal system is like a damped harmonic oscillator. 100 bonus points for having a cute animation of a moon on a surfboard "surfing" on the peak "gravito-inertial mode" location as it moves outwards from planet. Applies to Jupiter's and Saturn's moons

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:25 JST Prof. Sam Lawler

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     Talks about how tidal dissipation would change as the impact-melted Earth resolidifies.

     What about co-accretion? Not for our Moon, but works for jovian planets' large moons. Shows that many generations of moons formed around jovian planets and were eaten by planets during Solar System's planet formation phase. The ones we see today are the last generation before gas disk dispersed.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:25 JST Prof. Sam Lawler

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     She just told a story about being totally obsessed with Saturn as a middle schooler during the Voyager mission. She wrote a letter to JPL and they sent her a packet of Saturn photos and info! Comments that "I bet they had a good outreach budget back then." SIGH.

     Saturn has 1 big moon, did smaller moon get Roche-shredded into the rings? Rings appear to be young, so probably not the right explanation.

     Can co-accretion and giant impacts work together to explain Uranus/Neptune moons?

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:25 JST Prof. Sam Lawler

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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!

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Thursday, 25-Jun-2026 14:33:26 JST Prof. Sam Lawler

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     Robin Canup (SWRI) is giving a prize talk on the formation of the Moon. The Moon was definitely formed by a giant impact, but the details are hard! Mars-size impactor makes most sense, but you have to shed a bunch of angular momentum. Can do this with "evection resonance" which keeps the Moon-Earth-Sun in a specific configuration and messes with the Moon's eccentricity. Big problem: matching isotopic composition. Maybe impactor was the same as Earth? #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:19:59 JST Prof. Sam Lawler

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     Ryan LoRusso (Indiana U.) Cold Neptunes are common, can they help with redistributing planets in resonant chains? 5 Neptune systems migrate inwards in disk and make nice resonant chains, but are broken by planetesimals.

     Neptunes/sub-Neptunes are perfect for secular chaos which destroys resonance without too much ejection. Jupiters eject everything.

     Predict peak in debris disk activity at 10-100Myr due to this reshuffling.

     #DDA2026

     Mr. Bill repeated this.
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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:19:59 JST Prof. Sam Lawler

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     There is one more talk but I have to do other things now. #DDA2026 was super interesting and I learned a lot (though please note I skipped many talks, including all of the galaxy dynamics talks, due to my own bandwidth this week)

     I really appreciate getting to learn fascinating astronomy research that's happening - good motivation to keep fighting satellite companies for access to the sky.

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:00 JST Prof. Sam Lawler

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     Tommy Chi Ho Lau (U. Chicago) planetesimals form and then migrate inwards in disk, are affected by planets. Has code that does ALL of this, wow. Builds up structure of Kuiper Belt using disk dissipation and planet migration. By eye looks like their sim made WAY too many plutinos... Working on eroding after this initial simulation.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:00 JST Prof. Sam Lawler

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     Vaibhav Chhajed (Michigan State U.) pebble collapse simulations - uses many different size pebbles to mroe realistically simulate structures formed. Older sims use same size pebbles which may artificially increase strength of simulated bodies (like a crystal sort of). Wide ranges of sizes actually results in denser planetesimals due to more efficient packing, and makes more oblate shapes, more realistic with observations. Cool!

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:00 JST Prof. Sam Lawler

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     Agustin Heron (Indiana U. Bloomington) good title "Intruder alert"

     20% of Kepler systems have at least 1 pair of planets in or close to resonances. Using planetesimals to slowly change orbits and break resonant chains: time for REBOUND (with added sound effects by speaker haha)

     If planetesimals are "recycled" (don't get destroyed/kicked out of system after planet encounters), very small mass (fraction of Earth mass) can change orbits significantly.

     Maybe this happened to AU Mic?

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:00 JST Prof. Sam Lawler

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     Fei Dai (IfA U. Hawaii) resonant chains are common, but get disrupted early in planetary systems' history, only young systems have resonant chains.

     He's beat the 6:7 resonance (6-7 hehe), with a 9:8 resonant system. How did this form, super short stability timescale. Maybe a captured by a "trap" from evaporation front?

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:01 JST Prof. Sam Lawler

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     Why is this useful? Tells us about how much the Kuiper Belt was dynamically excited by past planet migration, helps us understand the population we see today and make predictions for future observations.

     Our paper (led by Mike Alexandersen) is in review, and will hopefully be accepted and on the arxiv within a couple weeks.

     Other LIDO papers that are already out:

     https://iopscience.iop.org/article/10.3847/PSJ/adc10c

     https://iopscience.iop.org/article/10.3847/PSJ/addd22 (this one will get talked about more in an upcoming talk)

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:01 JST Prof. Sam Lawler

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     Ruth Murray-Clay (UC Santa Cruz) "eyehole libration" in exterior p:1 resonances. We (LiDO) found a 10:1 resonator! I wrote about it for a general audience on page 31 of this pdf: https://www.rasc.ca/sites/default/files/publications/JRASC-2025-10-lr.pdf

     In high inclination orbits, p:1 resonances can librate around 180 *or* 0, and switch between these states. Eyehole libration happens when close approach to Neptune isn't at TNO perihelion

     I LOVE these beautiful surface-of-section plots Kat Volk makes

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:01 JST Prof. Sam Lawler

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     Dallin Spencer (BYU) warm classical TNOs are hard to explain, time to run a bazillion integrations! Sees the gap in density distribution at 4-6 degrees - this is right along 2 secular resonance (nu 8 and n 18) https://en.wikipedia.org/wiki/Secular_resonance

     Conjunctions pump eccentricity and move them out of this gap. Did this change the boundary of the cold classical belt?

     Upcoming paper will have proper elements for all known TNOs.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:01 JST Prof. Sam Lawler

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     Daniel Scheeres (CU Boulder) Binary small bodies are important and frequent. How do they form? Even more fun, how do you make 3 component systems (like asteroid Dinkinesh https://en.wikipedia.org/wiki/152830_Dinkinesh)

     Lots of simulations! Found an area of energy/angular momentum space that makes triples very easily. Finds lots of contact binaries.

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:02 JST Prof. Sam Lawler

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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!

     #DDA2026

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     Prof. Sam Lawler (sundogplanets@mastodon.social)'s status on Saturday, 27-Jun-2026 03:20:02 JST Prof. Sam Lawler

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     Rosemary Pike (Harvard MPC) my friend and collaborator: results from a survey I'm co-PI of, the LiDO survey, 140 new TNOs at 14 degrees or higher inclination.

     Hot classical TNO distribution (funny story, this was the most "boring" science case we could think of, but we needed something quick for the survey paper-other for fun science gets its own papers)

     We (well, mostly Kat Volk) built a dynamical stability model by mostly filling the hot classical region and eroding (yay REBOUND)

     #DDA2026