Galactic goings on

There’s a couple of reports coming through about some oddball galaxies that refuse to tow the line when it comes to how they should look and act.

Firstly to Galaxy NGC 1313, a barred spiral galaxy, 50,000 light years across, located 15 million light years from us. A new image from the Gemini Observatory shows a twisted galaxy full of star formation. Normally, star formation of this magnitude in this type of galaxy is set off either by disturbances caused by gravitational interactions with an impacting or interacting passing galaxy or by material being funneled through the bar and squashing up. However, 1313 is a lone galaxy adrift in the darkness of space. The star formation is also occurring in the arms, not the bar, so the second explanation is out too. But there is a heavy disturbance, a void of gas expanding in a bubble that has cut through an entire spiral arm and set off star formation on its edges. Quite what this is – it would take a thousand supernovae to create the energy driving this bubble, according to the report in Astronomy Now – isn’t yet known for sure. But it makes an interesting picture:

Credit: Gemini Observatory/AURA/Travis Rector (University of Alaska, Anchorage)

But it isn’t the only misbehaving galaxy out there. The Subaru telescope has been looking at distant galaxies – 10 billion light year distant galaxies that are unlikely to be featuring in my own telescope anytime soon. They found a number of ‘ordinary’ for that time elliptical galaxies, very compact compared to modern ones with ‘velocity dispersions’ – measurements of the speed with which stars orbit the nucleus of the galaxy – of 500km/s. So far so good, we expect there to be small compact ellipticals ready to come together and form bigger galaxies later on. However, there’s always one and in this case the one was a galaxy with a velocity dispersion of less than 326 km/s, likely to be one hundred times less dense and about two times larger than the others – more like a fully grown, more settled elliptical, such as those we’re used to round this end of the universe, which is about four times older. More details at Discovery and PhysOrg.

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