Scientists Uncover New Stars within Shouting Distance (Cosmically Speaking)
Imagine living in the same home for a few billion years and never having met your next-door neighbors, until now. Such is the case with planet Earth, a place in which scientists, including Georgia State astronomy professor Todd Henry, have only recently come to discover just how many stellar neighbors we have, and what they're like.
Working out of the Cerro Tololo Interamerican Observatory in Chile, Henry and his colleagues already have found more than two dozen previously unknown stellar neighbors within shouting distance of the Earth, at least on a cosmic scale. And they expect to find more, perhaps hundreds.
Henry says our stellar neighbors came to light because of Cerro Tololo's clear view of the southern sky (where little research on neighboring stars has been done) and because of the novel way he and his colleagues went about investigating them. The researchers not only measured the stars' movement across the sky, but their distance from the sun. "That's the key," explains Henry. "Astronomers are good at x and y, but z (distance) is hard to do."
Despite the difficulty, Wei-Chun Jao (M.S. '99 and Ph.D. '04), a postdoctoral student working with Henry, dared to investigate distance, focusing on the stars that appeared to move fastest across the sky (a clue they were close to Earth) and dubbed them "stellar roadrunners." The researchers are investigating about 400 stellar roadrunners and, so far, have found that 26 of them are, in fact, our next-door neighbors.
But the researchers also discovered something else. "We found a new kind of object," says Henry. "And it's all because Wei-Chun included in his thesis more than 500 systems (stellar roadrunners) — and a couple of weirdoes popped out."
Those weirdoes, explains Henry, are part of two binary star systems, each containing a white dwarf (a small, hot, dense star) and a red dwarf (a small, cool star). What makes these two systems so strange, says Henry, is that white dwarfs typically exist by themselves and are usually seen only when they're young because they grow fainter over time. Interestingly, the researchers found these white dwarfs only because of their next-door neighbors: two lighter, brighter companions.