Astronomers Find High Potential for Alien Life on TRAPPIST-1 Exoplanets
Last year, scientists discovered seven new Earth-sized exoplanets in our galaxy, and we've been observing them using the Hubble space telescope ever since.
Today, four new papers were published on the telescope's findings about the exoplanets, and the findings are nothing short of groundbreaking—not only are most of these planets habitable, and scientists agree it's incredibly likely that alien life exists on them as well.
The TRAPPIST-1 planets, so named because they orbit the cool red dwarf star TRAPPIST-1, which was in turn named for a Belgian beer that was beloved by the astronomers who discovered the star. In the TRAPPIST system, all seven planets are roughly the size of Earth, and confirmed by these studyes to be rocky, not gaseous.
Among them, TRAPPIST-1E is the most similar to Earth. Though it doesn't have an ocean, ice layer or thick atmosphere, the fact that it is still slightly denser to our planet suggests it might share a similar iron core. This lies in the system's "habitable zone," which the study in Astronomy and Astrophysics refers to as , "the circumstellar region where liquid water could exist on a planetary surface." Researchers found that these planets don't exude prominent spectroscopic signatures at near-infrared wavelengths either, "which rules out cloud-free hydrogen-dominated atmospheres for TRAPPIST-1 d, e and f....[a]s high-altitude clouds and hazes are not expected in hydrogen-dominated atmospheres around planets with such isolation, these observations further support their terrestrial and potentially habitable nature."
The study explains that because hydrogen is a powerful greenhouse gas, its presence in significant amounts affects a planet's habitability. "The far-infrared collision-induced absorption of molecular hydrogen may notably allow unbound planets to sustain habitable conditions by preserving their internal heat (from the decay of radionuclides and primordial heat)," it says, adding that "the predominance of atmospheric hydrogen affects the inner and outer edge of the Habitable Zone—the circumstellar region where water could stay liquid on a planetary surface."
This, while a large amount of hydrogen would seemingly enable life to exist by preventing outer planets from freezing, it would also hurt the likelihood of life existing on the inner planets. "In order to be habitable," it concludes, "the later must therefore have lost most of their atmospheric hydrogen or have never accreted/outgassed significant amounts of hydrogen in the first place."
"This scenario is very close to pure science-fiction, or pure fantasy," co-author Michaël Gillon wrote. "And still, TRAPPIST-1 does exist!"