Image: Artist's impression shows planetary system around pulsar PSR B1257+12
NASA/JPL-Caltech/R. Hurt (SSC)
This artist's impression shows the planetary system around pulsar PSR B1257+12, one of two pulsars known to be host to at least one planet. Such planets around pulsars may have powerful electromagnetic wakes around them.
By
updated 10/1/2012 7:59:16 PM ET 2012-10-01T23:59:16

Alien worlds that orbit the energetic dead stars known as pulsars may leave electric currents behind them — anomalies that could help researchers find more of these strange planets.

Astronomers know of only four "pulsar planets" so far, and much remains unknown about such worlds, but scientists propose that they formed in the chaos after the supernova explosions that gave birth to the pulsars.

A pulsar is a kind of neutron star, a stellar corpse left over from a supernova, a giant star explosion that crushes protons with electrons to form neutrons. Neutron star matter is the densest known material: A sugar cube-size piece weighs as much as a mountain, about 100 million tons. The mass of a single neutron star surpasses that of the sun while fitting into a ball smaller in diameter than the city of London.

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Pulsars spin extraordinarily rapidly, up to thousands of revolutions per second, and they flash like lighthouse beacons — hence their name, which is short for "pulsating star." They are also extremely magnetic — a kind of pulsar known as a magnetaris the most powerful magnet in the universe.

Despite the exotic nature of pulsars, they have been seen hosting planetary systems.

Around pulsars, "nobody would expect to find planets like those we know …  because the creation of a pulsar involves the supernova of a massive progenitor star," Fabrice Mottez, an astronomer and astrophysicist at the Paris Observatory, told SPACE.com. [Gallery: Strangest Alien Planets]

Mottez, lead author of a study into pulsar planets, and his colleagues suggested a new way to discover more of them: by looking for their wakes.

Pulsar planets could be interacting with the winds of electrically charged particles streaming from their pulsars, leaving powerful electric currents in their wake, the researchers said.

"In some circumstances, these currents would be almost as strong as those directly generated by the pulsar," Mottez said.

These electric currents should generate radio emissions. "The detectability of these planets with radio telescopes is currently under study," Mottez said.

Any world that survived the supernova that gave birth to a pulsar would be expected to have a very elongated, oval-like orbit. The supernova would have kicked the neutron star into motion at hundreds of miles per second, so planets that successfully followed these pulsars as they zoomed through space would have to move in comparably warped paths.

However, the four known pulsar planets all have very circular orbits, and they dwell rather close to their pulsars, at distances comparable to those of Mercury, Venus and Earth. This suggests they formed after the supernova, from debris that collected together shortly after the explosion.

The powerful magnetic fields and winds of particles from a pulsar should have profound effects on how planets form, and on smaller bodies such as asteroids and comets in its system, Mottez said.

The scientists presented their findings Sept. 28 at the European Planetary Science Congress in Madrid.

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Photos: Month in Space: January 2014

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  1. Southern stargazing

    Stars, galaxies and nebulas dot the skies over the European Southern Observatory's La Silla Paranal Observatory in Chile, in a picture released on Jan. 7. This image also shows three of the four movable units that feed light into the Very Large Telescope Interferometer, the world's most advanced optical instrument. Combining to form one larger telescope, they are greater than the sum of their parts: They reveal details that would otherwise be visible only through a telescope as large as the distance between them. (Y. Beletsky / ESO) Back to slideshow navigation
  2. A balloon's view

    Cameras captured the Grandville High School RoboDawgs' balloon floating through Earth's upper atmosphere during its ascent on Dec. 28, 2013. The Grandville RoboDawgs’ first winter balloon launch reached an estimated altitude of 130,000 feet, or about 25 miles, according to coaches Mike Evele and Doug Hepfer. It skyrocketed past the team’s previous 100,000-feet record set in June. The RoboDawgs started with just one robotics team in 1998, but they've grown to support more than 30 teams at public schools in Grandville, Mich. (Kyle Moroney / AP) Back to slideshow navigation
  3. Spacemen at work

    Russian cosmonauts Oleg Kotov, right, and Sergey Ryazanskiy perform maintenance on the International Space Station on Jan. 27. During the six-hour, eight-minute spacewalk, Kotov and Ryazanskiy completed the installation of a pair of high-fidelity cameras that experienced connectivity issues during a Dec. 27 spacewalk. The cosmonauts also retrieved scientific gear outside the station's Russian segment. (NASA) Back to slideshow navigation
  4. Special delivery

    The International Space Station's Canadian-built robotic arm moves toward Orbital Sciences Corp.'s Cygnus autonomous cargo craft as it approaches the station for a Jan. 12 delivery. The mountains below are the southwestern Alps. (NASA) Back to slideshow navigation
  5. Accidental art

    A piece of art? A time-lapse photo? A flickering light show? At first glance, this image looks nothing like the images we're used to seeing from the Hubble Space Telescope. But it's a genuine Hubble frame that was released on Jan. 27. Hubble's team suspects that the telescope's Fine Guidance System locked onto a bad guide star, potentially a double star or binary. This caused an error in the tracking system, resulting in a remarkable picture of brightly colored stellar streaks. The prominent red streaks are from stars in the globular cluster NGC 288. (NASA / ESA) Back to slideshow navigation
  6. Supersonic test flight

    A camera looking back over Virgin Galactic's SpaceShipTwo's fuselage shows the rocket burn with a Mojave Desert vista in the background during a test flight of the rocket plane on Jan. 10. Cameras were mounted on the exterior of SpaceShipTwo as well as its carrier airplane, WhiteKnightTwo, to monitor the rocket engine's performance. The test was aimed at setting the stage for honest-to-goodness flights into outer space later this year, and eventual commercial space tours.

    More about SpaceShipTwo on PhotoBlog (Virgin Galactic) Back to slideshow navigation
  7. Red lagoon

    The VLT Survey Telescope at the European Southern Observatory's Paranal Observatory in Chile captured this richly detailed new image of the Lagoon Nebula, released on Jan. 22. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of 11 public surveys of the sky now in progress using ESO telescopes. (ESO/VPHAS team) Back to slideshow navigation
  8. Fire on the mountain

    This image provided by NASA shows a satellite view of smoke from the Colby Fire, taken by the Multi-angle Imaging SpectroRadiometer aboard NASA's Terra spacecraft as it passed over Southern California on Jan. 16. The fire burned more than 1,863 acres and forced the evacuation of 3,700 people. (NASA via AP) Back to slideshow navigation
  9. Where stars are born

    An image captured by NASA's Spitzer Space Telescope shows the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This false-color infrared view, released on Jan. 15, spans about 40 light-years across the region. The brightest portion of the nebula is centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But Spitzer also can detect stars still in the process of formation, seen here in red hues. (NASA / JPL-Caltech) Back to slideshow navigation
  10. Cygnus takes flight

    Orbital Sciences Corp.'s Antares rocket rises from NASA's Wallops Flight Facility on Wallops Island, Va, on Jan. 9. The rocket sent Orbital's Cygnus cargo capsule on its first official resupply mission to the International Space Station. (Chris Perry / NASA) Back to slideshow navigation
  11. A long, long time ago...

    This long-exposure picture from the Hubble Space Telescope, released Jan. 8, is the deepest image ever made of any cluster of galaxies. The cluster known as Abell 2744 appears in the foreground. It contains several hundred galaxies as they looked 3.5 billion years ago. Abell 2744 acts as a gravitational lens to warp space, brightening and magnifying images of nearly 3,000 distant background galaxies. The more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang. (NASA / NASA via AFP - Getty Images) Back to slideshow navigation
  12. Frosty halo

    Sun dogs are bright spots that appear in the sky around the sun when light is refracted through ice crystals in the atmosphere. These sun dogs appeared on Jan. 5 amid brutally cold temperatures along Highway 83, north of Bismarck, N.D. The temperature was about 22 degrees below zero Fahrenheit, with a 50-below-zero wind chill.

    Slideshow: The Year in Space (Brian Peterson / The Bismarck Tribune via AP) Back to slideshow navigation
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