‘Alien megastructure’ star poses new puzzle

Image: Alien megastructure
An artist’s speculative representation shows a crumbling megastructure known as a Dyson sphere orbiting KIC 8462852. (Credit: Danielle Futselaar / SETI International)

He’s not saying it’s aliens – but an astronomer has raised new questions about KIC 8462852, the strange star that stirred up a debate about “alien megastructures” months ago.

In a paper submitted to Astrophysical Journal Letters, Lousiana State University’s Bradley Schaefer reviews archival photographic plates that show KIC 8462852 at various times going back to 1890. He reports that the star, which is 1,500 light-years away in the constellation Cygnus, faded by about 20 percent between the 1890s and the 1980s.

“This century-long dimming is completely unprecedented for any F-type main sequence star,” Schaefer writes.

KIC 8462852’s dimming was already worthy of note, due to observations by NASA’s Kepler space telescope that revealed unusual episodes during which the star faded by as much as 20 percent. That led Penn State astronomer Jason Wright to observe that such a pattern was consistent with what you’d expect if aliens were building an energy-generating megastructure known as a “Dyson sphere” around the star.

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Those weird spots on Ceres? Probably water ice

Image: Ceres' Occator Crater
This color-coded representation of Ceres’ Occator Crater shows differences in surface composition, highlight bright patches inside the crater. (Credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA)

For months, scientists have puzzled over weirdly bright spots of material shining on the asteroid Ceres, but now they say the spots are probably made of salty ice.

That determination, based on a detailed analysis of spectral data from NASA’s Dawn orbiter, comes in a paper published today by the journal Nature. Dawn’s images highlight one particular patch in a 106-mile-wide impact basin known as Occator Crater, but other spots are spread across the surface of the 590-mile-wide dwarf planet.

“The global nature of Ceres’ bright spots suggests that this world has a subsurface layer that contains briny water-ice,” the study’s principal author, Andreas Nathues of the Max Planck Institute for Solar System Research, said in a NASA statement. He and his co-authors suggest that cosmic impacts dig up enough surface material to expose the shiny ice.

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Is it aliens? SETI telescope targets mystery star

Image: Allen Telescope Array
The antennas of the Allen Telescope Array in California is collecting signals from a strange star known as KIC 8462852. (Credit: SETI Institute)

One of the premier telescope arrays in the search for extraterrestrial intelligence, or SETI, is focusing its antennas on an anomalously blinking star, thanks in part to speculation that the star called KIC 8462852 could harbor a network of alien megastructures.

The Allen Telescope Array, a complex of 42 radio dishes in Northern California that was funded in part by Seattle billionaire Paul Allen, has been collecting data about the star since Thursday evening, SETI Institute researcher Doug Vakoch said.

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