The above image is an artist's concept of a storm of comets around the star Eta Corvi. Image Credit: NASA/JPL-Caltech
NASA's Image of the Day Gallery for July 23rd features an image that was first published back on October 19, 2011. It's an artist's concept of a comet storm surrounding the star Eta Corvi. The image appeared as part of a news release associated with NASA's Spitzer Space Telescope.
Spitzer had detected signs of icy bodies raining down in the Eta Corvi system, just 59 light-years from Earth. The frozen downpour resembles what scientists think our solar system looked like several billion years ago during a period known as the "Late Heavy Bombardment."
During this epoch, comets and other frosty objects that fell inward from the outer solar system pummeled the inner planets. The barrage scarred our moon and produced large amounts of dust.
Eta Corvi is a spectral type F2 V yellow-white dwarf (main sequence) star, the sixth brightest in the constellation Corvus, the Crow. Eta Corvi is found at stellar coordinates (J2000, J2000) R.A. 12h 32m 04.2270s, Dec -16d 11m 45.627s and has an absolute magnitude of 2.99.
Spitzer's October 2011 announcement reported a band of dust around the star that strongly matched the contents of an obliterated giant comet. This dust is located close enough to the star that Earth-like worlds could exist, suggesting a collision took place between a planet and one or more comets. The Eta Corvi system is approximately one billion years old, which researchers think is about the right age for such a hailstorm.
The research findings were written-up in a paper published in the Astrophysical Journal. The lead author was Carey Lisse, senior research scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
Astronomers used Spitzer's infrared detectors to analyze the light coming from the dust around Eta Corvi. Certain chemical fingerprints were observed, including water ice, organics and rock, which indicate a giant comet source.
The light signature emitted by the dust around Eta Corvi also resembles the Almahata Sitta meteorite, which fell to Earth in fragments across Sudan in 2008. The similarities between the meteorite and the object obliterated in Eta Corvi imply a common birthplace in their respective solar systems.
A second, more massive ring of colder dust located at the far edge of the Eta Corvi system seems like the proper environment for a reservoir of cometary bodies. This bright ring, discovered in 2005, looms at about 150 times the distance from Eta Corvi as the Earth is from the sun. Our solar system has a similar region, known as the Kuiper Belt, where icy and rocky leftovers from planet formation linger. The new Spitzer data suggest that the Almahata Sitta meteorite may have originated in our own Kuiper Belt.
The Kuiper Belt was home to a vastly greater number of these frozen bodies, collectively dubbed Kuiper Belt objects. About 4 billion years ago, some 600 million years after our solar system formed, scientists think the Kuiper Belt was disturbed by a migration of the gas-giant planets Jupiter and Saturn. This jarring shift in the solar system's gravitational balance scattered the icy bodies in the Kuiper Belt, flinging the vast majority into interstellar space and producing cold dust in the belt. Some Kuiper Belt objects, however, were set on paths that crossed the orbits of the inner planets.
The resulting bombardment of comets lasted until 3.8 billion years ago. After comets impacted the side of the moon that faces Earth, magma seeped out of the lunar crust, eventually cooling into dark "seas," or maria. When viewed against the lighter surrounding areas of the lunar surface, those seas form the distinctive "Man in the Moon" visage. Comets also struck Earth or incinerated in the atmosphere, and are thought to have deposited water and carbon on our planet. This period of impacts might have helped life form by delivering its crucial ingredients.
And now, the mission particulars...
NASA's Jet Propulsion Laboratory (JPL), Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology (Caltech) in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. To learn more about Spitzer, visit http://www.spitzer.caltech.edu/ and www.nasa.gov/spitzer .
More information about exoplanets and NASA's planet-finding program is at planetquest.jpl.nasa.gov .
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