Stellar Encounters

Close encounters between stars are very rare; only a few of the 1011 stars in a typical galaxy undergo collisions. Nonetheless, encounters between stars play a role in formation of exotic stellar systems. Below are some simple model calculations of stellar encounters.


Unequal-Mass Collision

This simulation presents a slightly off-center parabolic collision of two stars with a mass ratio of 2:1. Initially, each star was modeled as an n = 1.5 polytrope. A total of 49152 equal-mass particles were used; the calculation was run with an adaptive SPH code.

Projected View. The system is viewed along the orbital axis. Colors indicate the value of the entropy function a(S); blue indicates low values, while red indicates high values.

Long movie (4.7 Mb); short movie (1.2 Mb); frames (184 kb).

Meridional Slice. Only the 4096 particles nearest the orbital plane at each instant are shown. Viewing angle and color scheme are as above. The same slice of 4096 particles is shown in the following animations as well.

Long movie (4.7 Mb); short movie (1.2 Mb); frames (183 kb).

Viscous Dissipation. Here color indicates viscous dissipation in shocks; dark blue regions are adiabatic, while bright red indicates the strongest shocks. A meridional slice is shown.

Long movie (4.7 Mb); short movie (1.2 Mb); frames (169 kb).

Density. Here color indicates gas density; dark blue regions have the lowest densities, bright red regions have the highest. A meridional slice is shown.

Long movie (4.8 Mb); short movie (1.2 Mb); frames (185 kb).

Internal Energy. Here color indicates internal energy or temperature; blue regions are cool, red regions are hot. A meridional slice is shown.

Long movie (4.7 Mb); short movie (1.2 Mb); frames (172 kb).


Joshua E. Barnes (barnes@ifa.hawaii.edu)
Last modified: January 1, 2000
http://www.ifa.hawaii.edu/~barnes/stars.html