David R. Rice

I made a travel map generator ✈️🌍
Drop in a list of country codes or names → see your visited & planned trips on a world map.
Runs fully in-browser (GitHub Pages).
Try it here: davidrrice.github.io/TravelMap/
#Travel #Maps

I think it says something that the "project's" prized fellowship went to a computer scientist. Although I try not to judge people for what postdoc they have to take nowadays.

A graph of pressure and temperature in the hydrosphere for a number of planets with varying surface temperatures. The curves go through the various regions of the phase diagram

Our new hydrosphere phase diagram is live for Magrathea: github.com/Huang-CL/Mag.... H2O ices, liquid, vapor, and supercritical. Largely inspired by the AQUA phase diagram from Haldemann et al. 2020, but with a couple of our own tweaks and ready to update with future EOS measurements.

Now if the eccentricity is greater than (1-q)/(1+q) where q is the mass ratio, the orbits are no longer nested, they form figure 8-like orbits with their ellipses rotated 180 degrees from each other. In this case, and only this case, does it make sense to say they both orbit each other. Rant over.

What does influence the geometry is the mass ratio and the eccentricity. In the barycentric frame, Pluto's apocenter is closer to the barycenter than Charon's pericenter. The orbits are nested, and we can easily say Charon orbits Pluto, and Pluto does not orbit Charon (and they both orbit the COM).

The barycenter’s position doesn’t change the geometry of the system; it’s just any systems center of mass. Inherent in the inside/outside central body definition is the central bodies density/radius something that has next to 0 to do with the orbital dynamics.

I'm not sure why I've decided to die on this hill radius, but Pluto & Charon are not a "binary planet" because the barycenter lies outside Pluto. That’s a misconception. Binary just means two bodies bound together: binary stars, binary black holes, binary asteroids, binary planet.

Once you have these it's easy to draw sillier reference frames like alpha Centauri A centric-frame or even better the Charon-centric frame.

There's a weird obsession with the barycenter being inside or outside the central body in astro-interested communities. I try to highlight here how the center of mass's location doesn't have an impact on the orbital configuration. The important quantity is actually the eccentricity.

The center of mass in the middle of the diagram with Pluto on a small circle and Charon on a larger circle. The eccentricity of near 0 is noted.

Alpha Centauri A and B on ellipses that are rotated 180 degrees to one another with center of mass at a focii. alpha Cen B is on larger ellipse. Makes a figure-8 like pattern.

Spent a day re-convincing myself that I know what an orbit is. Here are the barycentric orbits of Pluto-Charon and Alpha Centauri AB with correct proportions. Fun is that the radii of Pluto and Charon are even to scale with the orbit. #planetsci

Scary how often “I do my own research” means “I am the research subject”

Wait! It smells very strongly of garlic! No stealing internet: who wants to write an April’s fools article about K2-18b keeping vampires away.

What how why

@astrojake.bsky.social your favorite molecule

99.9% pure DMSO in large 16 oz container.

My MIL handed me pharma-grade DMSO for mosquito bites. Not FDA approved, but my self-study found it more statistical significance than DMS on K2-18b. #exoplanets

Great discussion here, just wanted to pipe in that one thing people miss in Liu Cixin's presentation of the DF is the "technological explosion" axiom. That the timescale and degree of a civilization's technological advancement is completely unknowable. In 3BP universe, any prey may become a predator

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Effect of Galactic Chemical Evolution on Exoplanet Properties. Jason H. Steffen (UNLV) et. al. https://arxiv.org/abs/2507.10942

The core mass fraction of planets with stellar age. Old stars have planets with lower core mass fractions and newer stars have higher core mass fractions.

Our new preprint just hit the arXiv: arxiv.org/abs/2507.10942 💥 We take a look at how the core mass fraction of planets may change through galactic time. My largest contribution is this plot with the planets from Weeks et al. 2025 reanalyzed with our interior model. 🔭🪐

Me standing in front of Washburn Observatory

Preparing to trade salt for fresh water—can you guess where I’ll be working next?

Big move next summer, big science starting sooner. Excited for what’s ahead in 2026!

the woke mob killed SExtractor

Uncertainties in the Inference of Internal Structure: The Case of TRAPPIST-1 f - IOPscienceSearchopens in new tab Uncertainties in the Inference of Internal Structure: The Case of TRAPPIST-1 f, Rice, David R., Huang, Chenliang, Steffen, Jason H., Vazan, Allona

Officially published today if you missed the arXiv drop a month ago!
iopscience.iop.org/article/10.3...

A lot of words to circle back to "go around the Sun".

So neat, but seriously this is how we get multiple comments saying "the Sun orbits the Earth" which is an entirely unhelpful and wrong description of nature.

I did not realize astronomers had started posting over there as much as they have. Every professor use to have a blank profile picture, now they’re all posting away.

…the day I connect with you…

Plot of the % wt water with r-cmf of the 7 Trappist-1 planets with the 1-sigma bounds using matplotlibs hatching.

Plot of the % wt water with r-cmf of the 7 Trappist-1 planets with the 1-sigma bounds filled with a transparent color.

I get a bit carried away with @matplotlib.org's hatching. But it's so helpful! The left plot you can pick any point in the middle and pretty quickly tell which 4 hatch marks are overlapping.

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Uncertainties in the Inference of Internal Structure: The Case of TRAPPIST-1 f. David R. Rice et. al. https://arxiv.org/abs/2504.16201

%wt Water versus R-CMF for the 5 outer Trappist-1 planets. A transform of the previous plot.

...and how to transform the ternary to WMF - R-CMF plot.

I think we're up to at least 10 groups using MAGRATHEA, our interior modeling code, and we're always excited for new users! github.com/Huang-CL/Mag...

A water-mantle-core ternary diagram showing 1-sigma bounds of 5 outer

Our new planet interior paper is accepted and up on arXiv, arxiv.org/abs/2504.16201! Explore all the knobs you can twist when modeling an Earth-like planet, in this case Trappist-1 f.

Don't miss the appendix where I detail the "correct" way to plot a ternary diagram (below)....

#exoplanets 🔭🧪🪐

Kids are calling the em dash the “ChatGPT hyphen”

a correlation “corner” plot with the upper empty corner filled with logos of the companies that typically sponsor podcasts and YouTube videos: nordvpn, hello fresh, duolingo, better help, etc

don’t give Elsevier any ideas 😭😭😭😭😭😭

“PromoPlot: Covering open-access fees by filling wasted space in corner plots”
arxiv.org/abs/2503.24254