T.J. Cox & Abraham Loeb
(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA)

Download the paper: PostScript (21 Mb), PDF (1 Mb)

Abstract: We use a N-body/hydrodynamic simulation to forecast the future encounter between the Milky Way and the Andromeda galaxies, given current observational constraints on their relative distance, velocity, and mass. Allowing for a comparable amount of diffuse mass to fill the volume of the Local Group, we find that the two galaxies are likely to collide in a few billion years - within the Sun's lifetime. During the first close encounter of the two galaxies, there is a 12% chance that the Sun will be pulled from its present position and reside in the extended tidal material. After the second close encounter, there is a 30% chance that the Sun will reside in the extended tidal material, and a 2.7% chance that our Sun will be more tightly bound to Andromeda than to the Milky Way. Eventually, after the merger has completed, the Sun is likely to be scattered to the outer halo and reside at much larger radii (>30 kpc). The density profiles of the stars, gas and dark matter in the merger product resemble those of elliptical galaxies. Our Local Group model therefore provides an prototype progenitor of late--forming elliptical galaxies.

CfA Press Release:

• When Galaxies Collide, our Solar System Will Go for a Ride

Movie of the interaction:

• Quicktime (3.4 Mb), mpeg4 (2.6 Mb), or avi (2.6 Mb)
  

Additional Images:

• A sequence of images that show the project stellar distribution during the encounter.
  
• A similar plot as above, only the projected gas distribution is now shown.
  
• The possible location of our Sun during the future encounter
  
• Our sketch of the initial configuration of our Local Group model.