More planets found orbiting two stars

TWIN STARS An artist’s depiction of Kepler 35b, a Saturn-size planet 5,400 light-years away, orbiting a pair of sun-size stars. (Lior Taylor via nyt)

In the ‘Star Wars’ movies, Luke Skywalker’s home planet, Tatooine, orbits two suns, giving it two sunsets and two sunrises every day. In September, scientists discovered the first planet in our galaxy that orbits two stars; now they have discovered two more and suggest that there are probably millions of these circumbinary planets in the Milky Way.

“We found two more, and that immediately tells us, wow, this wasn’t a fluke,” said William Welsh, an astronomer at San Diego State University who was involved in the research. “Now that we have three, we can compare the differences and start to learn more about these as a class of planetary systems.” Welsh and his colleagues report their discovery of the planets in the current issue of the journal Nature. The paper describes Kepler 34b and Kepler 35b, both gaseous planets about the size of Saturn; they are 4,900 and 5,400 light-years from the earth.

The planets were identified by NASA’s Kepler spacecraft, whose mission is to find other potentially habitable planets. Life could exist on a circumbinary planet, Welsh said. The first to be discovered, Kepler 16b, was just outside what is known as the habitable zone, where liquid water, and therefore life, can exist. It is just a little too far from its suns, and too cold for life.Kepler 34b, described in the current study, is also just outside the habitable zone, in this case a bit too hot for life.“That, to me, is interesting,” Welsh said. “It may be that we search a bit more and find that Goldilocks.”

Primate fossil adds to claw-toenail debate

Which came first, the nail or the claw?The answer is unclear, but researchers have discovered a clue: an early primate that had a toe bone with features of both a grooming claw and a nail.

A fossil of the 47 million-year-old primate, Notharctus tenebrosus, had a lemur-like grooming claw on its second digit, but it was flattened, a bit like a nail, according to a new study in the journal PLoS One. “What it really looks like is an intermediate morphology between grooming claw and a nail-like structure,” said an author of the study, Jonathan I. Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History. “It’s perhaps catching evolution in action.”

The toe bone specimen was collected more than a decade ago, but was sitting unprepared in a block of rock at the American Museum of Natural History in New York.“We took that block and CT-scanned it,” Bloch said. “The scan revealed that there was a semiarticulated foot.”What is not clear is whether the structure is a nail morphing into a claw, or a claw morphing into a nail.In the past, primates without a grooming claw were classified as anthropoids, along with humans, monkeys and apes. Those with claws are thought to be more like lemurs.

The discovery of the toe bone on Notharctus is important, Bloch said, because it has been proposed as a possible ancestor of humans.