Skip to contents

Precession constant from bundling: precession cycles per eccentricity bundle

Source: R/k_from_bundling.R
k_from_bundling.Rd

The scale-free way an eccentricity cycle does carry k. Count how many precession couplets make up one eccentricity bundle (or measure the ratio of the two periods, or the sideband spacing of the precession peak relative to its carrier) and invert p = n * (g_i - g_j) - f_term. No tuning, no sedimentation rate and no time scale are needed.

Usage

k_from_bundling(
  n,
  bundle_term = "e405",
  prec_term = "k+g5",
  age_ma,
  n_sd = 0.5,
  nsim = 20000,
  method = c("angular_momentum", "astrogeo22"),
  sampleorb = "U",
  g4g3_range_kyr = NULL,
  s4s3_range_kyr = NULL,
  seed = NULL,
  data_dir = NULL
)

Arguments

n

Number of precession (or obliquity) cycles counted per eccentricity bundle, or the measured ratio of the two periods (numeric, > 1, may be fractional). Required (no default).

bundle_term

Eccentricity term that forms the bundle (character): a named term such as "e405" (g2-g5), "e125" or "e130" (g3-g2), "e124" (g4-g2), "e99" (g3-g5), "e95" (g4-g5), any other name listed by astro_terms, or an expression of secular frequencies such as "g2-g5". Default="e405".

prec_term

Precession or obliquity term that is bundled (character; it must contain k), e.g. "k+g5" (main precession), "k+g2", "k+g4", "k+s3" (obliquity), or the aliases "prec"/"precession" and "obl"/"obliquity". Default="k+g5".

age_ma

Age of the record in Ma (numeric): one value, or c(min, max) to draw the age uniformly from that range in the Monte Carlo simulation. It sets the uncertainty of the secular frequencies (growing with the square root of age) and the obliquity used by ctest_earthmoon. Required (no default).

n_sd

One-sigma counting uncertainty of n, in cycles (numeric, >= 0); n is drawn from a normal distribution with this standard deviation. Default=0.5.

nsim

Number of Monte Carlo draws (integer, >= 0); 0 returns the plain point estimate without uncertainty. Default=20000.

method

How the precession constant is converted to Earth-Moon distance, length of day and obliquity (character, passed to ctest_earthmoon): "angular_momentum" (conservation of Earth-Moon angular momentum) or "astrogeo22" (inversion of the AstroGeo22 curve of Farhat et al., 2022). Default=c("angular_momentum", "astrogeo22"), i.e. "angular_momentum".

sampleorb

Shape of the distribution from which the uncertain secular frequencies g2, g3, g4, g5 and s3 are drawn (character): "U" uniform or "N" normal. Default="U".

g4g3_range_kyr

Range c(min, max) of the period of the g4-g3 term in kyr (numeric vector of length 2), drawn uniformly to allow for a chaotic resonance transition (g3 and g4 are moved symmetrically); NULL keeps g4-g3 at its La2004 value. Default=NULL.

s4s3_range_kyr

Range c(min, max) of the period of the s4-s3 term in kyr (numeric vector of length 2), drawn uniformly as for g4g3_range_kyr; NULL keeps s4-s3 at its La2004 value. Default=NULL.

seed

Seed of the random number generator (integer), so that the Monte Carlo results can be reproduced; NULL leaves the current random state unchanged. Default=NULL.

data_dir

Folder that contains the data tables AstroGeo22.txt and La04gisi.csv (character path). NULL uses getOption("cocoR.data") or the copies installed with WaverideR. Default=NULL.

Value

list with the Earth-Moon `summary`, `k_kyr`, `k_sd_kyr`, `k_ci95_kyr`, `n`, `terms`, `samples`, `predicted_n_model`, `reference` and `method`