Questions tagged [n-body-simulations]
Questions regarding simulations for an n-body problem.
87 questions
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What is the point of approximate Large Scale Structure simulation with neural networks?
People use N-body simulations to compute Large Scale Structure (LSS). To use this method you need to make assumptions about the underlying physics, e.g. the parameters of the Universe expansion, the ...
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When should we use direct O(N^2) N-body simulation (instead of other methods)?
I've read a small tutorial on N-body simulation methods. What it says about direct N-body simulation is:
These codes are often used in star cluster dynamics or in other contexts where multiple stars ...
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Large scale structure/Single galaxy simulation on GPU
I noticed that most of the tools for cosmological simulation (e.g. large scale structure or single galaxy evolution) are based on GADGET. It only allows to use CPU.
Why not GPU? What is the main ...
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How to speed up REBOUND python simulations on a Jupyter notebook?
I'm running Python based computational astrophysics simulations on a Jupyter notebook, with the help of a library called REBOUND (also using REBOUNDx), to create a simulation containing the solar ...
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How well are planetary formation models (e.g., determining $\mathrm{\dot{M}_{planet}}$) understood in 2024?
I know that planets can form through accretion, bulging up from $0$ to their final mass $\mathrm{M_{planet}}$ at $\mathrm{M}(t_f)$. I know that when studying Planetary formation and migration theories,...
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Corkscrew-like stable two-body system
I recently created a celestial body simulation in python for one of my classes. While playing around with different values I obtained a weird two-body stable system.. For context, these bodies are ...
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Three Body Problem using Python
I need help with an assignment. I'm doing a little project for a subject on my university and as the title says, its to find a solution to the three body problem restricted to a circular motion.
The ...
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How to plot different curves in the same polar cordinates in matplotlib?
I tried to plot the paths of particle of different sizes in the same polar coordinate using the code given below using matplotlib. somewhat like this:
Instead I got this plot:
while the path for ...
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How do various astrophysical models deal with so many orders of magnitude in scale? Are there completely different models for different scales?
If we just model our solar system's dynamics, one could use a straightforward numerical integrator with all n(n-1)/2 gravitational interactions along with some torques and non-gravitational forces. ...
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Help with simulating long-term orbital dynamics of exoplanetary systems using Rebound
I am a junior in high school working on an independent research project and I need help because I've reached the limits of my knowledge. My goal is to simulate the long-term orbital dynamics of ...
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Difficulty simulating trajectory of moon and sun for Apollo 11 mission
As an engineering student, I am doing a project about Kalman filtering and the mission Apollo 11. Now I tried to simulate the trajectory of the moon and sun for 3 days (the duration in which the ...
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Most accurate way of measuing the radius of a rubble-pile comet in an N-body simulation?
I have written an N-body simulation (close to finished) in C++ which focuses on the tidal disruption of comets.
I allow comets to be constructed in 2 ways:
Via my HCP (hexagonal-closest-packing) ...
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How to find zero velocity contours for circular restricted 3-body problem in x-y plane?
(I am having physics background; I am not an astronomer/astrophysicist.)
How to solve a single nonlinear algebraic equation in two variables, $x$ and $y$?
(I know that - if there are two variables, ...
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Would it be possible for a planet to orbit around a trinary star system in a figure 8 orbit?
I know that it is possible for a 3-body system to be "stable" in a figure-8 pattern. It's only stable if it is set up perfectly with no outside forces, but that's fine with me. If there were ...
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Different techniques for calculation of celestial bodies dynamics with different time-scales
Differential equations describing the dynamics of celestial bodies (rotation, nutation, precession and other effects) can be solved numerically, which makes it possible to study their general non-...
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Does the barycenter of an n-body system remain constant during collisions?
I am developing an n-body simulation software which simulates collisions. Most of these have a stationary frame of reference, meaning that orbiting objects may eventually move off the screen. To ...
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How to get JPL Ephemeris data to work in n-body simulation or why is Mercury flying to Jupiter
I wanted to make a n-body simulation for an art project.
I used this n-body algorithm, which includes a stable system for the Sun + gas giants, but no inner planets.
I wanted to simulate inner planets ...
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RAMSES fine multigrid Poisson solver fails to converge?
I am working on setting up N-body simulations of galaxy mergers. The initial conditions are generated from the DICE code, and looking at them, they seem very realistic. Unfortunately, when I let ...
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Initial state for a 3-body problem to create Figure 8 [ restricted to 2D ]
I've made an n-body simulation solution using the naive algorithm of O(n^2) in my library ChelseaaJS.
I was trying to make some pleasing 3 Body simulations.
I wanna do the 8 figure thing.
I know it's ...
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What is Gravitational softening length?
I was reading the Aquarius simulation preprint (Springel et al. 2008) The Aquarius Project: the subhalos of galactic halos as a reference for my internship. I came across the term Gravitational ...
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Orbital modelling, three bodies, leapfrog numerical integration
Apologies for the length of this question.
I'm modelling the motion of a single planet around the Sun using the equations:
$$dv_{x_{i}}/dt=a(t)=-GM_{SUN}x_{i}/r^{3},$$
where $x_{1}=x$, $x_{2}=y$ and $...
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Mass resolution in cosmological simulations [duplicate]
I've been reading papers about different cosmological simulations and they all talk about the "mass resolution" of those. Can someone please explain what does "mass resolution" ...
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Nbody problem solving on python with Leapfrog
I am relatively new to astronomical programming and I am trying to code a simulation of the solar system as simplified as possible on python. To do so, I am using numpy in order to have one array ...
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N-body simulation still losing precision despite using arbitrary-precision arithmetic and symplectic integrator
A while ago I asked 2-body orbits expanding in nbody simulation?. One thing that I noticed was that JavaScript does not have arbitrary precision, and that I used RK4 as my integrator, while it is ...
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Is it possible to have a stable 3 body system that orbits in a perfect circle?
I.e. a system that has 3 objects of equal mass, rotating around the system's center of gravity like so:
Please excuse the crude drawing, but I've just been reading The Three-Body Problem book by Liu ...
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Is there a tool to convert N-body RAMSES simulation file formats to GADGET 2 format in Python?
I am looking for a way to convert RAMSES files to GADGET-2 binary files because I want to use the package SimSpin (https://github.com/kateharborne/SimSpin/blob/master/R/make_simspin_file.R) which is ...
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Is it true that the 3 body problem can't be solved using the four basic functions, radicals, and integrals?
The two-body problem can be completely solved via two one-body problems, which only uses the four basic binary functions. However, the three-body problem cannot be solved with these functions and ...
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Does one need to consider relativistic effects when simulating the (or any) Solar system?
There was a question over at Physics asking how to improve a home-brew numerical simulation of the Solar system.
Even though in that case the defects were likely numerical, I started to wonder whether ...
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How to interpret skewness and kurtosis plots of galaxy snapshots?
What I did:-
I am analysing some simulation snapshots of the Milky Way and it is modelled as a dark matter halo – bulge – disc system. I produced some skewness (using ...
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Lagrange points for bodies in elliptical orbits?
Lagrange points are points of relative stability near the orbit of another, more massive body. Most of the examples of such points regard orbits with relatively low eccentricity. However, after ...
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How to calculate orbital velocity of binary star?
I am trying to simulate the Alpha Centauri AB System. I built the simulation, it works flawlessly when trying to simulate our solar system, and I am now trying to simulate the AB System. I found all ...
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Are there python packages to calculate mean line of sight velocity, linewidth and other distributions from galaxy simulation snapshots?
Does anyone know of any packages/functions in packages that can give mean line of sight velocities (losv) from a simulation snapshot (from the spatial and velocity coordinates or directly from the ...
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How to calculate mean line of sight velocity of stars after rotation of galaxy?
I am trying to calculate the mean line of sight velocity from a simulation snapshot of a galaxy after the galaxy is inclined by a certain angle, theta. I am coding it in python.
What I have done so ...
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Best way to procedurally generate an orbit given mass and eccentricity
As stated here, I've badly expressed my problem and have made what we call a XY problem (the question was well answered nonetheless) so I restate the question. Sorry for the inconvenience
I have a 2D ...
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Given mass, position and eccentricity, is there a way to get initial velocity in a 2-body problem?
I know that the we can get the eccentricity vector like that: $\mathbf{e} = \frac{\mathbf{v} \times \mathbf{h}}{\mu} - \frac{\mathbf{r}}{\|\mathbf{r}\|}$ (source: https://astronomy.stackexchange.com/...
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Uncertainities of orbital elements queried from JPL Horizons
I'm trying to retrieve the orbital elements' uncertainities for asteroids queried from NASA JPL Horizons. However I'm not able to find them in the query fields returned in python. Nor am I able to ...
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Where to find data on orbits of exoplanetary systems?
I hope this is the correct place to ask this question which entails asking if there is a database much like the JPL NASA one for the solar system, but for exoplanetary systems? I am conducting an n ...
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How to locate helpful and instructive books and resources about numerical methods in cosmology?
I am interested in the hydrodynamical and N-body simulations, and I want to use simulation results to examine the theoretical models.
Hence I am searching for some helpful and instructive books and ...
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What are the one-dimensional observables that can reveal the matter clustering properties of the Universe?
As we all know, the distribution of galaxies, which depend on the spatial coordinates, can help us understand the large-scale structure of the Universe. We can measure the distribution of galaxies ...
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Is this paper on globular cluster stability still up to date?
I'm looking to better understand the stability of globular clusters for an n-body dynamical simulation, specifically with respect to initial data conditions.
I know that the total potential energy ...
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Would it be a good idea to dockerize softwares in order to conduct hands-on tutorial sessions? [closed]
I am going to organize a tutorial in which I intend to train students on semi numerical simulations for reionization. Is it a good idea to supply use Docker to supply the codes?
What do you think ...
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How to distinguish primary hosts (stars) and orbiting satellites (planets) and tertiary bodies (moons) by their mass and trajectory?
Suppose one has run a gravitational simulation of N bodies (has the mass, vector positions, vector velocities, etc for each body), but knows nothing a priori about ...
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2-body orbits expanding in nbody simulation?
Recently, I designed an n-body engine and tested it with a binary star system. After a minute of running, the orbit began noticeably expanding:
Why is it happening, and is this natural? The source ...
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What fraction of matter is not bound to the galaxies, groups and clusters that we see?
We know that most of the matter in the universe has collapsed into galaxies and galaxies into groups and clusters and that a lot of matter is presently in clusters between the galaxies. But, what ...
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Which will destroy the Earth first: the Sun or Jupiter?
The sun is expected to grow in brightness over time, slowly heating the Earth until the oceans evaporate, leaving the planet uninhabitable.
Jupiter is the source of the largest perturbations to Earth'...
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Why is the boundary of friends-of-friends (FOF) halo corresponding to iso-density contour?
The friends-of-friends algorithm (hereafter FOF) is commonly used to find halos in cosmological simulations. (For more information, please refer to here and here)
I found that some literature argues ...
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Why do people choose 0.2 as the value of linking length in the friends-of-friends algorithm?
The friends-of-friends algorithm (hereafter FOF) is commonly used to find halos in cosmological simulations. And FOF depends on only one parameter, linking length, $l_\mathrm{link}=b \left(\frac{V_u}{...
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If an orbit is shifting due to orbital precession, is it still a Keplerian orbit?
I was thinking about orbits a few days ago, and realized that orbits shift/precess naturally. Given that a two-body problem with a star and a planet, if the planet has an eccentric orbit that ...
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'Little h' usage in cosmological simulations
I am running a cosmological simulation and am having some trouble putting things into code units. The physical distance units in my simulation are in terms of $\text{Mpc/h}$, where $h$ is the ...
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What kind of triangle is formed by three unequal masses in a circular restricted three body orbit?
This answer to Are the orbits of all triple star systems at least technically unstable? mentions:
There are known solutions to the gravitational three body problem that can be shown to be stable. ...
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