- Try one or more of the python tutorials and examples at the REBOUND github page
here.
Some interesting ones to try are:
- WHFast.ipynb: more practice with REBOUND
- Churyumov-Gerasimenko.ipynb: This simulates the past motion of the comet
Churymov-Gerasimenko
under the influence of Jupiter and Saturn.
Possible extensions:
- what
happens if you include all of the solar system planets?
- run the simulation for a long time into the future, with all
of the solar system planets included. Explore
will happen to the comet (Note: we are ignoring the evaporation of the comet).
- Churyumov-Gerasimenko
probably came originally from the Kuiper belt, which is between around
40AU and 48AU, and was then kicked inwards by Neptune.
Try placing the comet in that region on a nearly cicular orbit,
and see if you can get it to end up close to its observed orbit.
Where should it be initially placed for it to be safe from Neptune,
and where would it be in danger?
- Why has Churyumov-Gerasimenko has been in the news recently?
- Forces.ipynb: includes additional non-gravitational forces. Possible extensions:
- Use the migration force, but now with two planets instead of one.
Start your first planet at 1AU and the second one at 0.6AU.
If you migrate only the outer planet at a very low rate, you will
find that it "catches" the inner planet in a "resonance"
(Google to see what that means). See if you
can get the two planets to do that.
Note that three of Jupiter's moons--Io, Europa, and Ganymede--are caught in resonance.
It is thought that they got like this because they are being forced to migrate,
similar to the two planets you are simulating here.
-
Testparticles.ipynb: simulates many test particles in the presence of a planet. Possible extensions:
- What happens when you run the simulation much longer?
- What happens if you increase or decrease the mass of the planets?
- Radial velocities: Choose a planetary system you find interesting, download its
radial velocity ("RV") measurements, and then try reproduce the observed data with
the quoted parameters using REBOUND.
-
Note: To choose a planetary system, you can go to
exoplanets.org. For example, select the Table, then
use the filter NCOMP>1&&PLANETDISCMETH=='RV'
to select a system with more than 1 planet that was discovered by the radial velocity method.
After choosing a planet, you can find its RV either by going to the paper linked under
"Orbit Reference", or directly by
clicking on "Exoplanet Archive Link". Then, in the
lower left panel, open up "Associated Data" and check "Time Series", and then update.
An alternative procedure is to find an RV paper (e.g., Wright et al. (2009))
and choose one of the planets therein.
-
Possible extensions: where in the planetary system can small planets exist,
without
the risk of them being kicked out in the lifetime of the system? [see also
the
Testparticles.ipynb project below]
- Use the Systemic Console (link here)
to fit RV's directly, make plots or animations, etc.