Population Statistic: Read. React. Repeat.
Wednesday, February 23, 2021

What exactly is a “dark galaxy”?

“The ratio of dark matter to regular matter is at least 500-to-1, which is higher than I would expect in an ordinary galaxy,” [Cardiff University astronomer Robert] Minchin said. “However, it is very hard to know what to expect with such a unique object — it may be that high ratios like this are necessary to keep the gas from collapsing to form stars.”

Other potential dark galaxies have been found previously, but closer observations revealed stars in the mix. Intense visible-light observations reveal no stars in VIRGOHI21.

The invisible galaxy is thought to lack stars because its density is not high enough to trigger star birth, the astronomers said.

I didn’t realize it was possible to define a galaxy without the presence of stars. The definition of “galaxy” is an aggregate of stars, dust, and gas. In light of this dark matter body, maybe a redefinition is in order.

This dark stuff is a pretty big deal, on a universal level:

Dark matter makes up about 23 percent of the universe’s mass-energy budget. Normal matter, the stuff of stars, planets and people, contributes just 4 percent. The rest of the universe is driven by an even more mysterious thing called dark energy.

Puts things a bit into perspective.

- Costa Tsiokos, Wed 02/23/2005 07:45:00 PM
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  1. […] ’s been around for so long, the universe sure is a tricky thing to pin down. Whereas just a month ago, we were told that “dark matter” and “da […]

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