We can all go celebrate, and then get back to work.
And it was staring us right in the face all along; as ordinary, but dim matter.
Admittedly it was fairly difficult for us to see.
Researchers have looked for Dark Matter for decades (MACHOs and RAMBOs). But their search lately was generally limited to looking for tiny matter; exotic sand grain size or smaller (WIMPs).It turns out a huge percentage of the missing matter “particles” are enormous, the size of stars; a very dim type of star called Red Dwarf.
In fact, the next closest star to us (after our Sun), Proxima Centauri, is a Red Dwarf, a shining (dimly, we cannot see it with naked eyes) example of what has confounded “Dark Matter” researchers for decades.
Until about 2010, few suspected that Red Dwarf stars may be the most common type of star in our Universe. We now known that two-thirds, some 20, of our 30 nearest star neighbors are Red Dwarf stars. One estimate puts Red Dwarfs in our Milky Way at 75 percent of the stellar population making them the most common star type in our Milky Way.
However, because they are so dim, it is difficult to find more than a handful of them. (Because they are so difficult to detect, we don’t really know with much confidence how abundant they are in our own Milky Way. )
In our own Milky-Way spiral galaxy, Red Dwarfs seem to outnumber Sun-like stars by about a 100-1 ratio. Here is where recent sky studies by Pieter van Dokkum and Charlie Conroy come in. They found “there are about 1,000 red dwarfs in the biggest (Elliptical) galaxies for each sun-like star, and they account for about 60 percent of the mass of all the stars in these galaxies.”
Sixty percent of the mass of giant Elliptical galaxies, and yet we only learned Red Dwarfs were everywhere recently !
Since for every visible star like our Sun there are 1,000 Red Dwarfs, that should be almost exactly enough to account for any most heretofore “missing matter” in spiral galaxies. Seriously, when we redo the Virial Theorum (kinetic energy) calculations for a spiral galaxy – the amount of “missing matter” drops to a few percent of what was needed without Red Dwarfs.
Red Dwarfs “hiding” some 50 to 75 percent of “missing mass” in spiral galaxies could easily explain the anomalous galaxy rotation speeds that was up till now ascribed to the never detected “Dark Matter.”
One reason this is important to Cosmology, is that the leading “Big Bang” model, Lambda Cold Dark Matter, relies heavily (no pun intended) on the existence of Dark Matter; exotic, non-hot, non-visible, Dark Matter. This discovery conflicts with that hypothesis, since this Dark Matter is clearly, though faintly, “visible” and not at all exotic.
Would you please turn out the lights when you are done celebrating ?
Spectroscopic Confirmation of the Existence of Large, Diffuse Galaxies in the Coma Cluster, Van Dokkum, et all, April 2015
“A substantial population of low-mass stars in luminous elliptical galaxies” by
van Dokkum, Pieter G.; Conroy, Charlie 2010, Nature
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For more reading, try —
Dark Matter Fizzles Again, by Chuck Gallo (check out the references at the end of his article)