By Philip   |  02-07-2018   Science
Photo credit: Sciencenews.org

They're called Goldilocks planets. That rarity of a rock that, like Earth, is neither too hot nor too cold for life to thrive. Of course, the temperature isn't the only condition that must be in line to support the life of any sort, but according to a couple of recent scientific studies, one of the 7 planets circling the dim star TRAPPIST-1 might be a likely spot for life to exist. In fact, there is even a possibility that TRAPPIST-1 might be a potential future home for humans. Composed of rocky surfaces and featuring thin atmospheres according to mass measurements reported in the February 5 release of the journal Astronomy & Astrophysics. Three of the seven planets have atmospheres that appear not to be too hot to support life according to researchers publishing in Astronomy & Astrophysics.

There's always a catch though, isn't there? TRAPPIST-1 is a good clip from our current home on the third rock from the sun at an impressive 40 light-years from Earth, but with four of its planets within or near the "habitable zone" (temperature range that can sustain liquid water) the possibility of extraterrestrial life is worth looking into according to some scientists. The mass of the planets has a bit to do with the habitable nature of the planet. Previous looks into TRAPPIST-1 satellite planets didn't take into account the size of its planets. Mass of a planet is closely correlated with the planet's density. Density, in turn, is related to the planet's makeup. High density may be indicative of a lack of atmosphere (and no, we're not just talking about ambiance here). Low density is often a marker for a hydrogen-rich atmosphere which can result in a less than ideal greenhouse effect.

The latest studies relied on new computer-based techniques to infer the gravitational pull of the planets in the system. Simon Grimm, the astronomer at the University of Bern in Switzerland and his colleagues have recently estimated the mass of the seven planets with something like five to eight times more precision than was previously possible. From this more complete data, they are drawing a conclusion that the innermost planet most likely possesses a thick, viscous atmosphere like Venus. The other six are possibly covered in ice or oceans and, as a result, would be more likely to support life (human or otherwise). The fourth planet from TRAPPIST-1 is about the same density as Earth and even receives about the same amount of radiation from its star as Earth.

<blockquote>“This is really the cool thing: We have one planet which is very, very similar to the Earth,” Grimm says. “That’s really nice.”</blockquote>

Atmosphere and temperature are two major factors for being habitable as a planet. Using the Hubble Space Telescope, MIT astronomer Julien de Wit along with other MIT researchers and some members from Grimm’s team from Bern have been keeping an eye on the four middle planets in their orbit in search of certain key signatures related to near-infrared wavelengths of light that filter through the individual planets' atmospheres. This is to check for the possibility of the heat-trapping hydrogen that might result in a sort of "runaway greenhouse effect." So far no sign of hydrogen excess in the atmosphere through the Hubble according to the research published by De Witt, et al. in Nature Astronomy.

<blockquote>“We ruled out one of the scenarios in which it would have been uninhabitable."</blockquote>

All this is promising so far, but this doesn't necessarily mean the planets have atmospheres, much less that they are necessarily fit for life and much less that they could support human or extraterrestrial life whether intelligent or not, according to Stephen Kane, University of California, Riverside. One theory is that the star's radiation could have blown away the planets' atmospheres long ago. Researchers are hopeful that with the James Webb Space Telescope, set to be ready in 2019, more conclusive data might be derived.

Source:

https://www.sciencenews.org/article/trappist-1-exoplanets-life-friendly-atmosphere

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