Astronomers Found an Ancient Galaxy with a Halo of Dark Matter

Some 163,000 light - years from the Milky Way is a much smaller , much more ancient galaxy : Tucana II , so named for the tropical birdie - resemble configuration in which it sits . sit at the periphery of our galaxy ’s gravitative pull , Tucana II provides researchers with the opportunity to translate the composition of the earliest astronomical structures in the universe of discourse .

Now , a team of stargazer has found evidence of an extended dark thing halo around the galaxy . Their research waspublishedtoday in the journal Nature Astronomy .

“ We do it [ dark matter ] is there because in monastic order for galax to remain attach , there must be more matter than what we see visibly , from starlight , ” aver Anirudh Chiti , an astronomer at the Massachusetts Institute of Technology , in a phone call . “ That go to the speculation of drab matter be as an ingredient that holds galaxies together ; without it , galaxies that we know , or at least of the poppycock at their outskirts , would just fly asunder . ”

Just some of the visible matter in Tucana.

Just some of the visible matter in Tucana.Image: ESA/Hubble & NASA (Fair Use)

A dark matter halo is a region of gravitationally bind matter in infinite . ( The dark matter halo of the Milky Wayextends far beyondthe pinwheel that constitutes our galax ’s visible stuff and nonsense ) . The squad find that the gravitational bounds of Tucana II are between three and five times more monolithic than previously thought , demonstrate that even some of the oldest galaxies will have dark subject halos .

Tucana II happens to be the most chemically primitive galaxy that we currently know , meaning that some of its stars have very low alloy subject ( the world ’s heavier elements were produced later in time ) . The squad realized that Tucana II had the dark matter halo when observance of stars in that neighborhood of the sky reveal that the wiz were move in tandem .

“ If you just take care at the region of the sky where the galaxy exists , you do n’t really see a cluster or overdensity of star , ” Chiti , who is lead author of the recent paper , pronounce . “ It ’s only when you search at their velocities and realise it ’s a group of genius moving at the same velocity that you understand that there ’s a galax that exist there . ”

The Tucana dwarf galaxy, imaged by the Hubble Space Telescope.

The Tucana dwarf galaxy, imaged by the Hubble Space Telescope.Image: Hubble (Fair Use)

As survey co - author Anna Frebel , also an uranologist at MIT , put it in a university press release , the whorl of Tucana II ’s movement resembles “ bathwater going down the drainpipe . ” Compellingly , some of the galaxy ’s peripheral star are older than stars nigher to the galactic shopping centre . The squad hypothesizes that Tucana II may be the result of a previous astronomical merger , a cosmic clash that project one primitive galaxy eat by another , resulting in asterisk of different descent in the same galaxy .

Whether or not that theory of Tucana II ’s origin hold true , a like collision is sure in its future . Since it ’s within the gravitative realm of the much - more - massive Milky Way , eventually , the relatively lilliputian galaxy will be swallowed up by our own .

While astronomers be intimate how to recognize dark matter halo , they still do n’t have intercourse incisively what dark matter is . Besides finding its halos around galaxies , researcher are also looking for dark thing ’s identity inmysterious signals from neutron starsand in the material body oftiny , theoretical black yap .

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