A supernova like the one that formed this remnant, Cassiopeia A, may have sparked the formation of our solar system, a study suggests.
updated 8/6/2012 1:08:27 PM ET 2012-08-06T17:08:27

The shock wave from an exploding star likely helped trigger the formation of our solar system, according to a new 3-D computer model, researchers say.

The solar system is thought to have coalesced from a giant rotating cloud of gas and dust known as the solar nebula about 4.6 billion years ago. For decades, scientists have suspected a star explosion called a supernova helped trigger our solar system's formation. In particular, the shock wave from the explosion is thought to have compressed parts of the nebula, causing these regions to collapse.

According to this theory, the shock wave would have injected material from the exploding star into the solar nebula. Scientists have previously detected potential evidence of this pollution in meteorites. These contaminants are remnants of short-lived radioactive isotopes — versions of elements with the same number of protons as their more stable cousins, but with a different number of neutrons.

Short-lived radioactive elements decay over the course of millions of years, becoming a variety of "daughter" elements at known rates. ("Short-lived" is a relative term — other radioactive isotopes that scientists analyzing meteorites study may decay on timescales of billions of years.)

However, analysis of the short-lived radioactive isotopes and their daughter elements seen in primitive meteorites raised a challenge to the supernova theory of the solar system's formation. The evidence suggested the short-lived radioactive isotopes had to have formed in the supernova, made their way into the solar nebula and been trapped within the meteorites all in less than a million years. [Supernova Photos: Great Images of Star Explosions]

To see if a supernova could explain this pattern of isotopes seen in primitive meteorites, scientists developed computer models of supernova shock waves and solar system formation.

"The evidence leads us to believe that a supernova was indeed the culprit," said study lead author Alan Boss, an astrophysicist at the Carnegie Institution in Washington, D.C.

Previously, Boss and his colleague Sandra Keiser developed two-dimensional models involving the short-lived radioactive isotope iron-60, which is created in significant amounts only by nuclear reactions in massive stars and must have come either from a supernova or from a giant star called an AGB star. Thesemodels showed the iron-60 seen in primitive meteorites probably came from a supernova, since shock waves from AGB stars would be too thick to inject iron-60 into the solar nebula. In contrast, supernova shock waves are hundreds of times thinner.

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Now Boss and Keiser have developed the first 3-D computer models of supernova shock waves and solar system formation. These enabled them to see the shock wave striking the solar nebula, compressing it and forming a parabolic shock front that enveloped the cloud, creating fingerlike indentations in the cloud's surface. These "fingers" injected short-lived radioactive isotopes from the supernova into the nebula. Less than 100,000 years later, the cloud collapsed, triggering the birth of our solar system.

The 3-D models revealed that only one or two "fingers" could explain the short-lived radioactive isotopes found in primitive meteorites. However, the researchers are still trying to find various combinations of supernova shock wave parameters that will line up with observations of exploding supernovas. Also, they need to make the solar nebula rotate "so that it will form a star surrounded by a protostellar-protoplanetary disk after it collapses," Boss told

Boss and Keiser will detail their findings in an upcoming issue of the journal Astrophysical Journal Letters.

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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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