SFSU: Search for Signs of Life on Wolf 1061c

[bystander]

Astronomer Searches for Signs of Life on Wolf 1061 Exoplanet
San Francisco State University | 2017 Jan 20

[img3="An artist’s rendering of an exoplanet is shown. An exoplanet is a planet that exists outside Earth’s solar system. Illustration credit: NASA/Ames/JPL-Caltech"]http://news.sfsu.edu/sites/default/file ... main_1.jpg[/img3][hr][/hr]

Is there anybody out there? The question of whether Earthlings are alone in the universe has puzzled everyone from biologists and physicists to philosophers and filmmakers. It’s also the driving force behind San Francisco State University astronomer Stephen Kane’s research into exoplanets — planets that exist outside Earth’s solar system.

As one of the world’s leading “planet hunters,” Kane focuses on finding “habitable zones,” areas where water could exist in a liquid state on a planet’s surface if there’s sufficient atmospheric pressure. Kane and his team, including former undergraduate student Miranda Waters, examined the habitable zone on a planetary system 14 light years away. ...

But it’s not just Wolf 1061’s proximity to Earth that made it an attractive subject for Kane and his team. One of the three known planets in the system, a rocky planet called Wolf 1061c, is entirely within the habitable zone. With assistance from collaborators at Tennessee State University and in Geneva, Switzerland, they were able to measure the star around which the planet orbits to gain a clearer picture of whether life could exist there. ...

Characterization of the Wolf 1061 Planetary System - Stephen R. Kane et al

• arXiv.org > astro-ph > arXiv:1612.09324 > 29 Dec 2016 (v1), 13 Jan 2017 (v2)

http://asterisk.apod.com/viewtopic.php?t=35475

[Ann]

How fascinating!

At a distance of only 14 light-years, which is incredibly close for a star in the vicinity of the Sun, Wolf 1061 (parent star of planet Wolf 1061c) is only a 10th magnitude star, and completely invisible to any human eye even under the best possible observing conditions. According to Hipparcos, the V luminosity of Wolf 1061 is only 0.0014 solar!

What would it be like for a planet to be situated in the habitable zone of such a star? There would have to be huge differences compared with the situation on the Earth. For one thing, Wolf 1061 is an M4V star, making it very, very dim in visual light, but a lot brighter in infrared light. At a distance where a planet was warm enough to have liquid water on its surface, daylight would be very dim. Not that that, in itself, would put up a stop sign for the emergence of life on Wolf 1061c. After all, many life forms on the Earth live deep in the oceans, where there is no daylight at all.

But there might be other problems. A planet in the habitable zone of Wolf 1061 would have to be very close to its sun. Dim red star Wolf 1061 would loom very large in the skies of Wolf 1061c! If this little star is prone to any outbursts at all, that will be bad news to any surface-dwelling life forms on Wolf 1061c. Of course, life could survive underground or in oceans, perhaps under a thick ice cover, but that is a possibility for many planets in many solar systems. And Wolf 1061c may not have much ice, at least not for long periods of time:

Jamie Oppenheim wrote:

Since Wolf 1061c is close to the inner edge of the habitable zone, meaning closer to the star, it could be that the planet has an atmosphere that’s more similar to Venus. “It’s close enough to the star where it’s looking suspiciously like a runaway greenhouse,” Kane said.

Kane and his team also observed that unlike Earth, which experiences climatic changes such as an ice age because of slow variations in its orbit around the sun, Wolf 1061c’s orbit changes at a much faster rate, which could mean the climate there could be quite chaotic. “It could cause the frequency of the planet freezing over or heating up to be quite severe,” Kane said.

These findings all beg the question: Is life possible on Wolf 1061c? One possibility is that the short time scales over which Wolf 1061c’s orbit changes could be enough that it could actually cool the planet off, Kane said. But fully understanding what’s happening on the planet’s surface will take more research.

Ann