The Cosmic Puzzle

The formation and continued existence of this galaxy is a mystery

Credit: ESA/Hubble & NASA

NGC 1448 is a spiral galaxy located about 50 million light-years from Earth in the faint constellation of Horologium (The Pendulum Clock) located in the southern sky. NGC 1448 is more oval than circular with its spiral arms barely being visible. Although the stars in the galaxy appear still, they are constantly whirling around the galaxy’s dense core, with the spiral arms located on the inside whirling at a much faster rate. Usually, the arms around the core should be wound tighter as time progresses, but that is not what it happening here.

This is known as the ‘winding problem’. Galaxies have differential rotations, meaning different parts of a object move at a different speeds. The ones closest to the core move faster than the ones further out due to its proximity to the gravitational pull of the core. Since the the objects further out have larger orbits, it takes them more time to complete one revolution than those closer to the centre. The outer objects lag behind the inner objects which causes the spiral to wind up tighter and tighter until ultimately it disappears. In NGC 1448, this is not happening? Why? We don’t know yet.