Charged oxygen in ionosphere may offer biomarker for exoplanets

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Charged oxygen in ionosphere may offer biomarker for exoplanets

Post by Dragon on Mon Feb 19, 2018 6:04 pm

On January 9, 1992, astronomers announced a momentous discovery: two planets orbiting a pulsar 2,300 light years from our sun. The two planets, later named Poltergeist and Draugr, were the first confirmed "exoplanets"—worlds outside our solar system, circling a distant star. Scientists now know of 3,728 (confirmed) exoplanets in 2,794 systems, each one begging the question: "Is anyone else out there?"

"What more important question could we ask? Are we alone?" asks Boston University professor of astronomy Michael Mendillo. "I don't know of any more fascinating question in science."

For decades, astronomers have been searching these distant exoplanets for signs of life, mostly looking for that most essential molecule, water. But Mendillo and his colleagues have a different idea. In a paper published in Nature Astronomy on February 12, 2018, Mendillo, BU associate professor of astronomy Paul Withers, and Ph.D. candidate Paul Dalba (GRS'18) suggest looking instead at an exoplanet's ionosphere, the thin uppermost layer of atmosphere, which is whizzing with charged particles. Find one like Earth's, they say, packed with single oxygen ions, and you have found life. Or, at least, life as we know it.

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Re: Charged oxygen in ionosphere may offer biomarker for exoplanets

Post by Dragon on Mon Feb 19, 2018 6:05 pm


Credit: NASA Ames/SETI Institute/JPL-Caltech

The search for extraterrestrial life has focused mostly on exoplanets like Kepler-186f, shown here, which circle M-class stars in a “habitable zone” where water may exist. But “not all habitable zones are created equal,” says Mendillo, who notes that some exoplanets are dangerously close to their stars, exposing them to hazardous radiation that might prevent life as we know it. “Earth’s habitable zone has a little more hospitality.”

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Re: Charged oxygen in ionosphere may offer biomarker for exoplanets

Post by Dragon on Mon Feb 19, 2018 6:07 pm


Credit: NASA

A 10-minute, infrared exposure of Earth taken from the moon during the Apollo 16 mission. The bright yellow is “dayglow” from atomic oxygen (O). On the dark side, “nightglow” bands, arising from atomic oxygen ions (O+) in the ionosphere, can be seen near the equator

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Re: Charged oxygen in ionosphere may offer biomarker for exoplanets

Post by Dragon on Mon Feb 19, 2018 6:08 pm



The planets have been nicknamed "Earth's seven sisters."

 
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Re: Charged oxygen in ionosphere may offer biomarker for exoplanets

Post by Dragon on Mon Feb 19, 2018 6:11 pm



Astronomers have discovered the first Earth-size planet orbiting a star in the "habitable zone" -- the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exist in the habitable zone of stars other than our sun.

 
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Re: Charged oxygen in ionosphere may offer biomarker for exoplanets

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