The red dwarf star Trappist-1 that shot to fame just last week because NASA had discovered that it was the parent star of at least seven planets, all Earth-sized with three in the habitable zone, may have already received an upgrade to the number of planets circling the star that could have the potential for sustaining alien life. New research indicates that volcanism and the warming of a planet's atmosphere could extend a star's habitable zone as much as 60 percent.
Astronomers at Cornell University have found, the Daily Mail reported, that the planets displaying active volcanoes on more distant, frozen worlds could improve the chances of detecting alien life by extending the perimeter of a star's habitable zone, that area within a star system where liquid water can form, by as much as two-thirds what was originally believed. The scientists found that volcanism and the warming of a planet's atmosphere could produce conditions where alien life might evolve, thus generating biosignatures for which astronomers and astrobiologists search.
"On frozen planets, any potential life would be buried under layers of ice, which would make it really hard to spot with telescopes," said Ramses Ramirez, a research associate at Cornell's Carl Sagan Institute and the lead author of the study. "But if the surface is warm enough, thanks to volcanic hydrogen and atmospheric warming – you could have life on the surface, generating a slew of detectable signatures."
The study found that the greenhouse gases -- like hydrogen, oxygen, and carbon dioxide -- generated by a planet's volcanism could extend a star's habitable zone from 30 to 60 percent. The new findings not only expanded the potential number of habitable exoplanets throughout the universe, it did so for our own solar system. And that expansion, of course, only expands the potential for discovering alien life.
The Daily Mail notes that the habitable zone in our own solar system, by the older calculations, extends to just beyond the orbit of Mars, or 1.67 astronomical units (one astronomical unit, an AU, is equal to the distance from the Sun to the Earth). With the revised calculations, the zone then extends to the asteroid belt (2.4 AU) located between Mars and Jupiter.
"We just increased the width of the habitable zone by about half, adding a lot more planets to our 'search here' target list," said Ramirez.
The extension is achieved, according to the research, when volcanism on an exoplanet produces hydrogen in enough amounts to add to the warming effect for the otherwise icy world.
Ramirez explained, "Adding hydrogen to the air of an exoplanet is a good thing if you're an astronomer trying to observe potential life from a telescope or a space mission. It increases your signal, making it easier to spot the makeup of the atmosphere as compared to planets without hydrogen."
Earth-like exoplanets can only hold their hydrogen for only a few million years, the researchers say, but active volcanoes putting hydrogen back into the atmosphere of a planet could alter the dissipation. Subsequent hydrogen increases in the planet's atmosphere make it easier for astronomers to detect what could be a potential biosignature.
"Where we thought you would only find icy wastelands, planets can be nice and warm-- as long as volcanoes are in view," said Lisa Kaltenegger, Cornell professor of astronomy and director of the Carl Sagan Institute.
Given the new findings, an extension of the habitable zone of the newly discovered Trappist-1 planets could extend outward to possibly include a fourth planet in the system. At present, as NASA announced last week, there are three planets in the habitable zone of the red dwarf star.
Kaltenegger noted that the discovery of multiple worlds in the habitable zone "is a great discovery because it means that there can be even more potentially habitable planets per star than we thought. Finding more rocky planets in the habitable zone -- per star -- increases our odds of finding life. Although uncertainties with the orbit of the outermost Trappist-1 planet 'h' means that we'll have to wait and see on that one."
As good as the news is for those searching for alien life, another scientist from Cornell University, noted astrophysicist Neil deGrasse Tyson, stated that there was some bad news that leavens the excitement and could potentially adversely impact whether alien life could survive on not only the three (now perhaps four) exoplanets but all seven. As reported by the Inquisitr, Tyson explained that young red dwarf stars like Trappist-1 were extremely volatile and its discharge of solar wind particles (every two hours, according to NASA) very well could have destroyed any atmospheres on any and all of the planets in its system, making the planets less likely to host alien life.
Still, increasing the odds of habitability increases the odds of eventually discovering alien life. Tyson suggested that the discovery of the seven Earth-sized worlds gave rise to notion that the number of exoplanets might exceed the number of stars. And as Tyson said after delivering the disappointing news (and admitting that there was still a chance life might be found on a Trappist-1 planet), scientists should also be expanding the search parameters on alien life, asking themselves "how many possible ways exist for being alive."
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