Notices by Hanno Rein (hannorein@mastodon.social), page 2

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Hanno Rein (hannorein@mastodon.social)'s status on Sunday, 13-Jul-2025 07:04:57 JST Hanno Rein
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💫🌎 My group's new paper is now on the arXiv. We do something really simple that I'm surprised nobody has done before: a convergence study of N-body simulations of the Solar System. We find that timesteps can be ridiculously large and still yield physical results. Specifically, the timestep can be as large as 1/3 of Mercury's orbital period, or ~32days. This works because the Solar System is chaotic and secular, not mean-motion resonances are driving the evolution. https://arxiv.org/abs/2507.04987
In conversation about a year ago from mastodon.social permalink
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  On the convergence of N-body simulations of the Solar System
  
  Most direct N-body integrations of planetary systems use a symplectic integrator with a fixed timestep. A large timestep is desirable because simulations run fast. However, simulations yield unphysical results if the timestep is too large. Surprisingly, no systematic convergence study has been performed on long (Gyr) timescales. In this paper we present numerical experiments to determine the minimum timestep one has to use in long-term integrations of the Solar System in order to recover the system's fundamental secular frequencies and instability rate. We find that timesteps of up to 32 days, i.e. a third of Mercury's orbital period, yield physical results in 5 Gyr integrations. We argue that the chaotic diffusion that drives the Solar System's long-term evolution dominates over numerical diffusion and timestep resonances. Our results bolster confidence that most simulations in the literature are indeed converged and provide guidance on how to run time and energy efficient simulations while making sure results can be trusted.
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Hanno Rein (hannorein@mastodon.social)'s status on Sunday, 13-Jul-2025 07:04:57 JST Hanno Rein

🎉 Paper submitted!

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Hanno Rein (hannorein@mastodon.social)'s status on Monday, 07-Jul-2025 06:13:48 JST Hanno Rein

#insects
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Hanno Rein (hannorein@mastodon.social)'s status on Thursday, 16-Jan-2025 08:55:47 JST Hanno Rein

☀️🌑 Is anyone else super stoked about the upcoming solar eclipse here in #Canada?
In conversation Thursday, 16-Jan-2025 08:55:47 JST from mastodon.social permalink
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1. A screenshot of a Home Screen Widget showing the next solar eclipse at “your current location”. It’ll be on March 29th 2025 at 7am. Maximum sun cover: a meagre 2.45%.
  https://files.mastodon.social/media_attachments/files/113/834/799/555/418/908/original/bc5e31f6a49ce363.jpeg
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Hanno Rein (hannorein@mastodon.social)'s status on Thursday, 16-Jan-2025 08:55:46 JST Hanno Rein
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You can download my free eclipse live app to see a prediction for your location: https://apps.apple.com/ca/app/solar-eclipse-live/id6480014046
In conversation Thursday, 16-Jan-2025 08:55:46 JST from mastodon.social permalink
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  ‎Solar Eclipse Live
  
  This app lets you explore all solar eclipse until the year 2200 for any location on Earth. You can preview each eclipse from your current location (or select a location manually). The app uses the most accurate research-grade NASA ephemeris data (DE440) to calculate the most accurate eclipse timings…
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Hanno Rein (hannorein@mastodon.social)'s status on Monday, 18-Nov-2024 09:42:32 JST Hanno Rein

I got a paper to review that reused a lot of my GPL code, repackaged it, and released it with an MIT license. Awkward.

In conversation Monday, 18-Nov-2024 09:42:32 JST from mastodon.social permalink