If nearby exoplanet harbours life, it is a VERY weird place
Monday, January 11, 2016, 2:30 PM - A close look at Wolf 1061c, now Earth's nearest potentially-habitable neighbour, is revealing this alien world as a very strange place to live.
Wolf 1061c, an alien "super-Earth" located just 14 light years away, is now the closest confirmed potentially-habitable exoplanet we know of.
"It is a particularly exciting find because all three planets are of low enough mass to be potentially rocky and have a solid surface, and the middle planet, Wolf 1061c, sits within the 'Goldilocks' zone where it might be possible for liquid water – and maybe even life — to exist," Dr. Duncan Wright, the lead researcher from the University of New South Wales, said in a statement.
"It is fascinating to look out at the vastness of space and think a star so very close to us – a near neighbour – could host a habitable planet. While a few other planets have been found that orbit stars closer to us than Wolf 1061, those planets are not considered to be remotely habitable," Dr. Wright said.
Based on the latest assessment from the University of Puerto Rico's Planetary Habitability Laboratory, if this planet actually turns out to be habitable, living there would be very different from what we are used to here on Earth.
Firstly, the planet orbits a red dwarf star, about one quarter the size and mass of our Sun. Secondly, the planet is over four times more massive than the Earth, and likely around 60 per cent larger. This puts it at around 20,000 km across, giving the planet the same surface area as two and a half Earths. Because of its size and mass, if you were standing on the surface of the planet, you would feel round 70 per cent heavier, so a 150 lb person would feel as though they weighed 250 lbs.
Based on the planet's star, and thus how much light and heat it receives, plus the planet's size and mass, Wolf 1061c only ranks as 76 per cent "Earth-like" on the Planetary Habitability Lab's Earth Similarity Index (ESI).
The size of this world would almost guarantee a thicker atmosphere and very likely more water (although both will depend on the environment around the star and how the planet's conditions developed over time), but the strangest aspects of the planet come from its orbit.
In the simulation presented above, the three planets that orbit red dwarf star Wolf 1061 are shown travelling in idealized circular orbits, however, in reality the system is laid out a bit more like the representation below:
Simulation of the Wolf 1061 star system by UNSW, using Universe Sandbox 2. The simulation shows the orbits in relation to the star's habitable zone (green), as well as the regions too warm (red) and too cold (blue) for liquid water to exist on a planet's surface.
From the UPR Planetary Habitability Laboratory:
The Wolf 1061 star system (left) and orbit of Wolf 1061c (right). Credit: UPR PHL
According to the UPR analysis, at its farthest distance from its parent star, Wolf 1061c is just one-tenth of the distance between the Earth and the Sun. If it orbited around our Sun, this super-Earth would lie well within the orbit of Mercury, and would simply be a burned-out cinder of a world.
Fortunately, since Wolf 1061c orbits is a cool red dwarf star, it resides in the star's habitable zone, the region around the star where conditions are generally just right - not too hot or too cold - for liquid water to exist on a planet's surface. That means that it has the potential to be Earth-like, with an atmosphere, water and possibly even life on its surface.
There's one twist to this, though. The planet is so close to this star that it is very likely tidally-locked, so that its year - the length of time it takes to travel once around the star - is exactly the same length as its day. This means that it would always have one side facing towards the star, and would likely be what is often called an "eyeball Earth", as shown to the right.
These planets are thought to have a fairly dry, desert environment at the very centre of the star-facing side, with a narrow temperate zone surrounding that, and ice encasing the edges and the entire dark side. A thicker atmosphere could moderate this, but it would be very different from what we're used to here on Earth.
Stranger still, due to its elliptical orbit, Wolf 1061c could experience seasonal changes - even if it doesn't have an axial tilt - simply due to the fact that it gets significantly closer and farther away from the star. Whereas Earth's distance from the Sun only changes by about 3 per cent between its closest distance (perihelion in January) and its farthest distance (aphelion in July), Wolf 1061c's distance changes by more like 30 per cent between its closest (periastron) and farthest (apoastron) points from its star.
Given this, Wolf 1061c would go through a full Earth-year's worth of seasonal changes - summer, fall, winter, spring and back to summer - nearly twice every Earth month. Once again, any atmosphere present around the planet may moderate these changes, but it would still provide the conditions for some pretty crazy weather patterns, with shifts from snow storms and blizzards to heat waves and thunderstorms, every 18 days or so.
With Wolf 1061c's proximity to Earth, it may even be possible to verify these kinds of speculations about the planet in the near future.
"The close proximity of the planets around Wolf 1061 means there is a good chance these planets may pass across the face of the star," said study co-author Dr. Rob Wittenmyer, also of the University of New South Wales. "If they do, then it may be possible to study the atmospheres of these planets in the future to see whether they would be conducive to life."
Related Video: Watch an Earth-like exoplanet circling star Gliese 667C