Twisted beauty when whirls collide

This dramatic image from the Hubble space telescope shows how our own galaxy might look if it were involved in a cosmic collision with a similar city of stars.

Two spiral galaxies that once resembled the Milky Way are twisted and distorted by tidal forces as they crash together.

The result looks like a single, bizarrely shaped galaxy with the hearts of each galaxy almost completely merged and long graceful tails with new stars being born.

Such is the vast distance between stars that the billions of other suns in each galaxy are likely to be sailing past each other with few if any actual impacts taking place.

The double-galaxy, lying about 250 million light-years away in Cancer, the Crab, is labelled NGC 2623 or Arp 243. Astronomers’ studies show that massive quantities of gas are pulled from each galaxy towards the centre of the other as they come together.

And with their merger almost complete, long tidal tails of young stars formed in the mix of gas and dust stretch out to reveal the collision has taken place. Around 100 bright star clusters have been found in the prominent lower tail alone.

The collision has also stirred into action a supermassive black hole at the centre of one of the galaxies. As it swallows in a swirling disk of matter, the energy heats the disk up. The result is that the galaxy’s nucleus shines brilliantly across a range of wavelengths in the spectrum – it is so bright in the infrared that it is included in a special group of very luminous infrared galaxies by professional scientists.

This remarkable view was produced from images taken in 2007, before Hubble’s recent upgrade, using the Advanced Camera for Surveys. It was taken by a team led by US astronomer Aaron S. Evans.

Picture: Hubble’s dramatic view of the galaxy merger. Credit: NASA, ESA and A. Evans (Stony Brook University, New York & National Radio Astronomy Observatory, Charlottesville, USA).

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available.

Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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