Tropes

newscientist 00082.txt

#Rainbow galaxies reveal why cosmos is full of spirals (Image: ALMA (ESO/NAOJ/NRAO)/ SMA/CARMA/IRAM/J. Ueda et al. Each entry in this visual catalogue of psychedelic pictures captures a violent collision of galaxies revealing for the first time how galaxies like the Milky way form. These images show the carbon monoxide gas detected in neighbouring galaxies 40 to 600 million light years from Earth in their final stages of merging. The colours show how this gas was moving: blue represents gas that is moving towards us while red indicates gas that is moving away. Out of 37 galaxies observed these 30 all show gas rotating around the centre of the galaxy meaning they are disc galaxies in the making. For the first time there is observational evidence for merging galaxies that could result in disc galaxies. This is a large and unexpected step towards understanding the mystery of the birth of disc galaxies says Junko Ueda from the Japan Society for the Promotion of Science. Ueda and her team made the observations using data from the ALMA radio telescope. Computer simulations suggested that when galaxies merge they usually form a single blob-shaped galaxy classed as elliptical. However most of the galaxies in the universe are shaped pancake disc galaxies such as lenticular galaxies and our own spiral Milky way. As this rogues'gallery of galactic mergers shows a disc-shaped offspring is a common result of a collision. Journal reference: The Astrophysical Journal Supplement Series DOI: 10.1088/0067-0049/214/1

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