There is a massive halo of dark matter circling a dwarf galaxy similar to the Milky Way, much more significant than scientists have traditionally assumed.
The Tuscan II circling ring is as much as five times as large as predicted by physicists. This claim therefore shifts our view of the dwarf galaxy's composition.
Perhaps almost as critically, the tale of the very earliest galaxies in the universe should also be re-written, as it indicates that they have expanded much farther and more massively than we had realized.
There are hundreds of dwarf galaxies on the Milky Way's edges, believed to be left behind by the very first galaxy to develop. The universe known as Tucana II is among the earliest of them, and is ultra-faint and sits some 163,000 light-years from Earth.
Experts published their report, 'An extended halo around an ancient dwarf galaxy,' in Nature Astronomy.
What is Dark Matter?
Dark matter is a fictional form of matter that is believed to make up more than 85 percent of the universe, and a local abundance, or halo, of dark matter, is thought to tie the galaxy together.
The theory of dark matter, initially known as 'lost matter,' was conceived in 1933, after the observation that only one percent of the mass required to prevent galaxies from overcoming the gravitational pull of the cluster was used by the mass of all-stars in the Coma cluster of galaxies.
American astronomers Vera Rubin and Kent Ford reported variations in star orbits in galaxies in the 1970s, NBC News said per DailyMail.
The observation ignited a belief in the science community that the anomalies were triggered by masses contained in and near galaxies of unseen 'dark matter.'
Many scientists believe that about 85 percent of all the matter in the universe is dark matter, but it has never been seen or measured for such a significant number.
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What's Tucana II?
Based on its stars' metal content, Tucana II is one of the most primitive dwarf galaxies observed. Stars with a low metal content actually evolved quite early on, when heavy metals were not yet created by the cosmos.
In the case of Tucana II, astronomers had previously found a handful of stars with such a low metal content near the center of the galaxy that the galaxy was considered the most chemically basic of the ultrafine dwarf galaxies known.
This is the first evidence that Tuscana II, one of the first galaxies in the universe, hosts an extended halo of dark matter, and experts have hypothesized that it is three to five times more extensive than predicted.
Galaxies That Are Not-So-Wimpy
MIT graduate student Anirudh Chiti said in a statement that to connect these stars that are too far apart, Tucana II has far more mass than we thought. This suggests the other first relic galaxies are often likely to have these kinds of expanded halos.
The latest study reveals that at the edge of Tucana II, there are stars. They are a long distance from its core but still apparently trapped in its gravitational influence, indicating that there is some matter there, undetected but exerting energy on the stars themselves.
Moreover, the stars on edge are more primitive than the ones at the center. The mismatch means that two baby galaxies colliding with each other may potentially have resulted from it, which would be another first in the analysis.
Researchers expect that the finding would be accompanied by even further searches of other dwarf galaxies and relics from the early universe in the hope of establishing that they too contain stars at far longer distances than commonly believed.
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