In the light of ancient days, stellar cores radiated with dense dark-matter interactions. Some astronomers now believe dark stars evolved on a titanic scale-many with diameters up to, and perhaps exceeding, 30 a.u. (1 a.u. or astronomical unit equals 93 million miles, the distance between Earth and Sun). With a diameter of 30 a.u., an average dark star would have filled the space between the Sun and the planet Neptune! (It is likely these early stars had families of planets. So, we can only imagine what these hypothetical planets looked like.)
A typical dark leviathan would have been cooler than later fusion-driven stars such as our Sun, but what they lacked in temperature, they made up for in sheer size and mass.
A large, dark stellar object would have had a mass of 10,000 Suns with a luminosity of 1 billion Suns. It is staggering to the human mind to imagine such suns existing on such a vast scale.
Now to the dark star and black hole connection.
We now think that large dark stars eventually collapsed into giant black holes. These giant holes became the seeds around which today's galaxies, even our Milky Way, formed. Smaller dark stars also ran out of dark matter to burn; ignited fusion fuel resulted from the final dark-matter reactions, and these suns eventually collapsed, too. Small dark stars probably left behind black holes, too.
Infrared space telescopes are perfect instruments to search for dark stars of the distant past, but the task is herculean. Light from these early stars would be shifted to the far-infrared, so NASA's successor to the Hubble Space Telescope-the planned 2014 James Webb Space Telescope-might hunt for signatures of dark stars; however, space agency officials aren't sure if even their advanced JWST will be up for the daunting task.
What's in the Sky: In the WNW this weekend, look for Mercury and Venus in the sky together. On April 1, one hour after sunset, both planets will be a mere 3.2 degrees apart.
Louis Varricchio, M.Sc., is a former senior science writer at the NASA Ames Research Center. He is a current member of the NASA-JPL Solar System Ambassador program in Vermont. Varricchio is the recipient of the U.S. Civil Air Patrol's Maj. Gen. Chuck Yeager Aerospace Education Achievement Award. You can contact him at: email@example.com.