• Tag Archives Kepler
  • The Most Mysterious Star in Our Galaxy

    In the Northern hemisphere’s sky, hovering above the Milky Way, there are two constellations—Cygnus the swan, her wings outstretched in full flight, and Lyra, the harp that accompanied poetry in ancient Greece, from which we take our word “lyric.”

    Between these constellations sits an unusual star, invisible to the naked eye, but visible to the Kepler Space Telescope, which stared at it for more than four years, beginning in 2009.

    “We’d never seen anything like this star,” says Tabetha Boyajian, a postdoc at Yale. “It was really weird. We thought it might be bad data or movement on the spacecraft, but everything checked out.”

    Kepler was looking for tiny dips in the light emitted by this star. Indeed, it was looking for these dips in more than 150,000 stars, simultaneously, because these dips are often shadows cast by transiting planets. Especially when they repeat, periodically, as you’d expect if they were caused by orbiting objects.

    The Kepler Space Telescope collected a great deal of light from all of those stars it watched. So much light that Kepler’s science team couldn’t process it all with algorithms. They needed the human eye, and human cognition, which remains unsurpassed in certain sorts of pattern recognition. Kepler’s astronomers decided to found Planet Hunters, a program that asked “citizen scientists” to examine light patterns emitted by the stars, from the comfort of their own homes.

    In 2011, several citizen scientists flagged one particular star as “interesting” and “bizarre.” The star was emitting a light pattern that looked stranger than any of the others Kepler was watching.

    The light pattern suggests there is a big mess of matter circling the star, in tight formation. That would be expected if the star were young. When our solar system first formed, four and a half billion years ago, a messy disk of dust and debris surrounded the sun, before gravity organized it into planets, and rings of rock and ice.

    But this unusual star isn’t young. If it were young, it would be surrounded by dust that would give off extra infrared light. There doesn’t seem to be an excess of infrared light around this star.

    It appears to be mature.

    And yet, there is this mess of objects circling it. A mess big enough to block a substantial number of photons that would have otherwise beamed into the tube of the Kepler Space Telescope. If blind nature deposited this mess around the star, it must have done so recently. Otherwise, it would be gone by now. Gravity would have consolidated it, or it would have been sucked into the star and swallowed, after a brief fiery splash.
    Boyajian, the Yale Postdoc who oversees Planet Hunters, recently published a paper describing the star’s bizarre light pattern. Several of the citizen scientists are named as co-authors. The paper explores a number of scenarios that might explain the pattern—instrument defects; the shrapnel from an asteroid belt pileup; an impact of planetary scale, like the one that created our moon.

    The paper finds each explanation wanting, save for one. If another star had passed through the unusual star’s system, it could have yanked a sea of comets inward. Provided there were enough of them, the comets could have made the dimming pattern.

    But that would be an extraordinary coincidence, if that happened so recently, only a few millennia before humans developed the tech to loft a telescope into space. That’s a narrow band of time, cosmically speaking.

    And yet, the explanation has to be rare or coincidental. After all, this light pattern doesn’t show up anywhere else, across 150,000 stars. We know that something strange is going on out there.

    When I spoke to Boyajian on the phone, she explained that her recent paper only reviews “natural” scenarios. “But,” she said, there were “other scenarios” she was considering.

    Jason Wright, an astronomer from Penn State University, is set to publish an alternative interpretation of the light pattern. SETI researchers have long suggested that we might be able to detect distant extraterrestrial civilizations, by looking for enormous technological artifacts orbiting other stars. Wright and his co-authors say the unusual star’s light pattern is consistent with a “swarm of megastructures,” perhaps stellar-light collectors, technology designed to catch energy from the star.

    “When [Boyajian] showed me the data, I was fascinated by how crazy it looked,” Wright told me. “Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build.”

    Boyajian is now working with Wright and Andrew Siemion, the Director of the SETI Research Center at the University of California, Berkeley. The three of them are writing up a proposal. They want to point a massive radio dish at the unusual star, to see if it emits radio waves at frequencies associated with technological activity.

    If they see a sizable amount of radio waves, they’ll follow up with the Very Large Array (VLA) in New Mexico, which may be able to say whether the radio waves were emitted by a technological source, like those that waft out into the universe from Earth’s network of radio stations.

    Source: The Most Mysterious Star in Our Galaxy – The Atlantic


  • NASA Kepler Results Usher in a New Era of Astronomy

    Scientists from around the world are gathered this week at NASA’s Ames Research Center in Moffett Field, Calif., for the second Kepler Science Conference, where they will discuss the latest findings resulting from the analysis of Kepler Space Telescope data.

    Included in these findings is the discovery of 833 new candidate planets, which will be announced today by the Kepler team. Ten of these candidates are less than twice the size of Earth and orbit in their sun’s habitable zone, which is defined as the range of distance from a star where the surface temperature of an orbiting planet may be suitable for liquid water.

    At this conference two years ago, the Kepler team announced its first confirmed habitable zone planet, Kepler-22b. Since then, four more habitable zone candidates have been confirmed, including two in a single system.

    New Kepler data analysis and research also show that most stars in our galaxy have at least one planet. This suggests that the majority of stars in the night sky may be home to planetary systems, perhaps some like our solar system.

    “The impact of the Kepler mission results on exoplanet research and stellar astrophysics is illustrated by the attendance of nearly 400 scientists from 30 different countries at the Kepler Science Conference,” said William Borucki, Kepler science principal investigator at Ames. “We gather to celebrate and expand our collective success at the opening of a new era of astronomy.”

    From the first three years of Kepler data, more than 3,500 potential worlds have emerged. Since the last update in January, the number of planet candidates identified by Kepler increased by 29 percent and now totals 3,538. Analysis led by Jason Rowe, research scientist at the SETI Institute in Mountain View, Calif., determined that the largest increase of 78 percent was found in the category of Earth-sized planets, based on observations conducted from May 2009 to March 2012. Rowe’s findings support the observed trend that smaller planets are more common.

    An independent statistical analysis of nearly all four years of Kepler data suggests that one in five stars like the sun is home to a planet up to twice the size of Earth, orbiting in a temperate environment. A research team led by Erik Petigura, doctoral candidate at University of California, Berkeley, used publicly accessible data from Kepler to derive this result.

    Full article: http://www.nasa.gov/ … astronomy/index.html