As­tronomers show that galax­ies can change shape

Focus-Science and Technology - - Discoveries -

THE FIRST EV­I­DENCE that galax­ies can change shape has been found by an in­ter­na­tional team of as­tronomers led by Prof Steve Eales from Cardiff Univer­sity’s School of Physics and As­tron­omy.

“Many peo­ple have claimed be­fore that this meta­mor­pho­sis has occurred, but by com­bin­ing Her­schel and Hub­ble, we have for the first time been able to ac­cu­rately mea­sure the ex­tent of this trans­for­ma­tion trans­for­ma­tion,” ” said Eales. His team pub­lished their find­ings in the jour­nal Monthly No­tices Of The Royal As­tro­nom­i­cal So­ci­ety in Au­gust.

The team were able to do this af­ter making ob­ser­va­tions of 10,000 galax­ies and clas­si­fy­ing them into two types: ro­tat­ing, flat discs (such as the Milky Way) or large, spher­i­cal galax­ies. Then, us­ing the Hub­ble and Her­schel tele­scopes to peer at galax­ies much fur­ther away – and thus much fur­ther back in time – the team were able to com­pare to­day’s galax­ies with those formed in the af­ter­math of the Big Bang.

Eales’s team found that 83 per cent of the stars formed im­me­di­ately af­ter the Big Bang were lo­cated in ro­tat­ing disc galax­ies. But to­day only 49 per cent of stars are found in such galax­ies, with the rest found in large,large spher­i­cal ones,ones sug­gest­ing­sug­gest many galax­ies have un­der­gone ma­jor trans­for­ma­tions dur­ing their life­times.

One pos­si­ble cause for such a trans­for­ma­tion could be two disc galax­ies merg­ing into one an­other af­ter col­lid­ing. But it’s also thought there may be cases where stars in a disc galaxy are drawn to­wards the cen­tre and group to­gether to form a spher­i­cal galaxy.

New re­search sug­gests that galax­ies were once more uni­form than those we see to­day

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