Archive for October 3, 2011

Galaxies con Alma

Posted in The Universe and Stuff with tags , , , , on October 3, 2011 by telescoper

It’s back to School with a vengeance today, so not much time for the blog. However, I couldn’t resist mentioning the fact that the European Southern Observatory’s Atacama Large Millimetre Array, known to its friends as ALMA, has at last opened its eyes. Or at least some of them. ALMA in fact is an interferometer which eventually will comprise 66 dishes,   working together to with baselines as long 16km to synthesize a single huge aperture. The preliminary results that have just been released were obtained using just 16 dishes so they only offer a taste of what the full ALMA will do when it’s completed in 2013.

ALMA works in the millimetre wave region of the spectrum, operating at wavelengths between 0.3 and 9.6 mm. The overlap with the  wavelength range probed by the Herschel Space Observatory together with its much higher resolution than Herschel, which is a single telescope of only 3.5m diameter, makes the two very complementary: Herschel is good for surveying large parts of the sky, because it has a large field of view, whereas ALMA can do high-resolution follow-up of selected regions.

Anyway, here is ALMA’s view of the Antennae Galaxies (left) shown next to an optical image taken with the Very Large Telescope (VLT).

The system consists of two galaxies so close together that they interact strongly with each other via enormous tidal forces, hence the disturbed structure. The coloured regions in the ALMA image show radiation emanating from carbon monoxide present in huge clouds both in and between the galaxies. Altogether these clouds contain several billion solar masses worth of gas which has never been viewed before.

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