Deadheads and B-movie sci-fi fans rejoice: Astrophysicists have come up with reason to believe that invisible dark stars may actually exist.
University of Utah associate professor Paolo Gondolo has been tinkering with the idea of star formation early in the universe's life, and how that might have been affected by dark matter.
Dark matter is an as-yet-theoretical substance that scientists believe makes up roughly 23 percent of the universe, compared to just 4 percent for the visible matter that makes up the stars, planets and presidential candidates that we're able to observe directly.
Thus far, researchers have not been able to directly detect this mysterious substance, but have inferred its existence from its effect on the motion of galaxies.
Traditionally, early stars are viewed as having been the result of hydrogen and helium atoms that clumped together into clouds, cooling and becoming denser until fusion ignited them.
However, Gondolo and his colleagues argue that adding dark matter into the equation could have changed the outcome, under the right conditions. Its constituent particles – such as "neutralinos," one still-hypothetical candidate particle for dark matter – might have collided and annihilated each other, producing quarks, anti-quarks, and heat.
That heat would have kept proto-stars from shrinking, leaving them large, warm, and too "fluffy" to ignite. Such unfiery giants – ranging from four times to 2000 times the diameter of earth's orbit – would be invisible in the visible light spectrum, but would radiate gamma rays, neutrinos, and antimatter particles, as well as infrared light.
Gondolo's paper contends that these "dark stars" (he wanted to call them "brown giants, but was overruled by a colleague) would have appeared about 80 million to 100 million years after the big bang. Some could have collapsed into black holes, helping to explain the relatively early appearance of black holes on the intergalactic scene.
Some could ultimately have turned into normal stars.
But maybe some are still around. As might be expected from working with hypothetical particles and as-yet-unobserved matter, the model has some wiggle room. But with the predicted radiation signature of gamma rays and antimatter, astronomers might be able to find them, if they do exist. Says Gondolo:
The dark star study will be published next month in Physical
Review Letters.
Were the first stars dark? [University of Utah press release]
(Image: Artist's conception of the infrared signature of a "dark star." Credit: University of Utah)
