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Actually implement IAU 29 resolution B3 #2024

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merged 7 commits into from
Dec 9, 2018

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@eggrobin eggrobin commented Dec 9, 2018

While #1846 introduced a reference to the IAU resolution, it kept the existing constants.

These are ancient, introduced by 3084f81 in March 2014, predating the relevant IAU resolution by more than a year; being masses, they are fundamentally unsuitable as nominal values, as gravitational parameters are known with much greater accuracy than 𝐺 is.

Switch to the system of nominal solar and planetary conversion constants.

astronomy/trappist_gravity_model.proto.txt Outdated Show resolved Hide resolved
@@ -10,7 +10,7 @@ gravity_model {
# for life?", Vida et al., 2017.
body {
name : "Trappist-1"
mass : "0.0890 M☉"
mass : "0.0890 GM☉"
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Should this be GM☉, (GM)☉, (GM)ᴺ☉, (𝒢ℳ)ᴺ☉?

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It's fine the way you wrote it.

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But it should be gravitational_parameter, not mass. How does it even parse?

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Done.

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constexpr GravitationalParameter TerrestrialGravitationalParameter =
3.986'004e14 * (Pow<3>(si::Metre) / Pow<2>(si::Second));
constexpr GravitationalParameter JovianGravitationalParameter =
1.266'865'3e17 * (Pow<3>(si::Metre) / Pow<2>(si::Second));
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I would have grouped all the parameters for a planet together: equatorial radius/polar radius/gravitational parameter separated by a blank line. I would also have alphabetized the planets (thus Jovian < Terrestrial).

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No, let's keep the order used by the IAU tables.

reference_angle : "0 deg"
angular_frequency : "109.256 deg / d"
name : "Trappist-1"
gravitational_parameter : "0.0890 GM☉"
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Note that this pull request does not regenerate the cfg files, as the tools would copy over 0.0890 GM☉ and the like instead of converting to SI units, which would cause interchange issues for strings passed in structs.

We want to rerun the optimization soon anyway.

@pleroy pleroy merged commit c757f84 into mockingbirdnest:master Dec 9, 2018
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