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Andromeda galaxy same size as the Milky Way

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  • 17-02-2018 11:46am
    #1
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,838 Mod ✭✭✭✭


    So we won't be engulfed in 4 billion years, it will be a merger of equals or something.

    https://www.theregister.co.uk/2018/02/16/andromeda_galaxy_milky_way/
    The escape velocity for Andromeda is about 470 kilometers per second – a lower than expected value, which suggests scientists overestimated the amount of mass it contains.

    "By examining the orbits of high speed stars, we discovered that this galaxy has far less dark matter than previously thought, and only a third of that uncovered in previous observations," Kafle said.


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    #2
    ps200306
    Registered Users Posts: 1,591 ✭✭✭ps200306


    The MNRAS paper (understandably) doesn't seem quite as sensational as TheRegister article. There have been previous estimates in better agreement with this new one -- it seems to be some more recent ones that are out of line, and even the lower end of those is just about in range. Figure 1 from MNRAS:

    dwqENHM.png

    But it does seem to be in conflict with ΛCDM estimates for the mass of a dark matter halo. I was hoping they'd say more about how ΛCDM might be bullsh*t ... but no such luck. :pac:


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