Credit: ESO. Acknowledgements: Jean-Christophe Lambry
This Picture of the Week shows the Vela ring galaxy,
visible as a bright core surrounded by a baby blue halo. As the name
suggests, this ring galaxy — located in the southern constellation of
Vela (The Sails) — is notable due to its compact core and large circular
belt of gas and stars.
It is thought that ring galaxies
like this are created when larger galaxies are punctured by a smaller
galactic aggressor, which, passing through the heart of its more
sizeable victim, triggers a shock wave that spreads outwards. This
pushes gas to the galaxy’s periphery, where it begins to collapse and
form new stars. The Vela ring galaxy is unusual in that it actually
exhibits at least two rings, suggesting that the collision was not a
recent one.
This picture also features a galaxy known
as ESO 316-33, seen just above and to the left of the Vela ring galaxy,
and a bright star known as HD 88170.
