Feature/yarkovsky acceleration

[simon-van-hulle]

This pull request contains an implementation for the Yarkovsky effect, based on the simplified formulation described a.o. Perez-Hernandez & Benet (2022) - reference:

$$\boldsymbol{a}_\text{y} = A_2\left(r0\over r{Sun}\right)^2\boldsymbol{\hat t}$$

• $\boldsymbol{\hat t}$ is the heliocentric transverse unit vector (in the direction of the velocity)
• $A_2$ is a scalar, referred to as the body's Yarkovsky Parameter
• $r_0 = 1$ AU
• $r_{Sun}$ is the distance to the Sun

Unit tests include a test with a mass-less asteroid in a circular orbit around the Sun (no perturbations except the Yarkovsky acceleration). The drift in the semi-major axis is then compared to the expectation described by

$$\dot {a} = 2A_2\dfrac{(1-e^2)r_0^2}{np^2}$$

• $a$ is the semi-major axis
• $e$ is the eccentricity
• $n$ is the mean motion
• $p$ is the semi-latus rectum

[DominicDirkx]

Hi Simon,

I've merged your code, and have added the implementation of the Yarkovsky acceleration partials, allowing it to be used in a state and parameter estimation, and have added the option to estimate the Yarkovsky parameter along with initial states and other parameters.

Thanks so much for the time you've invested in this!!!

Dominic