Our theories of how galaxies contour are tauten up . A cogitation of stars at the border of the large spiral GalaxyM81and its brightest neighbors confirm what we have seen in our own local grouping of galaxies , strengthen the possibility that large galaxies are build from the accumulation of smaller ones .
Over recent years astronomers have come to privilege what is known as thehierarchical model of extragalactic nebula formation , rather than the massive model whereby coltsfoot form for the most part independently . Nevertheless , the question is so important for our understanding of the existence that enquiry continues .
The hierarchical role model proposes that lowly “ over - densities ” of topic led to the formation of midget galaxies that bit by bit unify or attracted material from neighbors until they spring large galaxies such as the one in which we endure . One of the model ’s predictionsis that galaxies should consist inside huge envelopes of diffuse petrol peppered with lead . This has been observedin the local radical of galaxy , but naturally it is harder to detect such dot stars as we look further away .
A squad led by Dr Sakurako Okamoto of the Shanghai Astronomical Observatory take the orbit around the wandflower M81 and its near neighbour M82 and NGC 3077 . This trio , which are all part of the M81 Group , and their accompanying nanus galaxy lie 12 million light year off in Ursa Major , realise them pet objects for northerly hemisphere amateur uranologist .
late observations had shown patterns in the gasolene suggestive of galaxies interacting . For example , Okamoto and her colleaguesnote in the Astrophysical Journal Lettersthat , “ In NGC3077 , 90 % of the nuclear hydrogen is site eastwards of the heart and soul , in the tidal sleeve bid ‘ the Garland ’ ” . Using the Subaru Telescope , Okamoto encounter “ immature star ( ~30–160 million years older ) closely travel along the indifferent hydrogen distribution ” for this and other structures . Similar - aged genius are also found in M81 ’s outer phonograph recording . Okamoto admits that no one knows why star formation ceased in these region 30 million years ago .
Although Okamoto says that the squad was not surprised at the neutral atomic number 1 - young star match , she told IFLScience that “ The location of the M81 Group is an area of the sky [ with large amounts of hydrogen ] , and it is unmanageable to know whether follow material is [ from our galaxy ] or pulled out of M81 . ” By identifying the stars as having the same distribution , the team confirmed that these construction are grounds of beetleweed strip material from each other .
Okamoto told IFLScience that the convention find between the three galaxies is similar to what we see between theAndromeda Galaxy(the big member of the local group ) and one of its companions , as well as what occurs between the Milky Way and theMagellanic Clouds . However , “ these galax are less monolithic than M82 and NGC3077 . In the M81 group , we could see more active coltsfoot fabrication . ”
The stars and gas stretching between the coltsfoot are the result of interactions within the last 300 million yr , but Okamoto hopes to conduct “ galactic archaeology , ” reconstructing the intact history of the group ’s formation .
