Getting Closer! Is a Habitable Exoplanet Orbiting Red Dwarf Gliese 163?

 

           

 

A new superterran exoplanet was found in the stellar habitable zone of the red dwarf star Gliese 163 by the European HARPS team. The planet, Gliese 163c, has a minimum mass of 6.9 Earth masses and takes nearly 26 days to orbit its star. Superterrans are those exoplanets between two and ten Earth masses, which are more likely composed of rock and water. Gliese 163 is a nearby red dwarf star 50 light years away in the Dorado constellation. Another larger planet, Gliese 163b, was also found to orbit the star much closer with a nine days period. An additional third, but unconfirmed planet, might be orbiting the star much farther away.

Gliese 163c could have a size between 1.8 to 2.4 Earth radii, depending if it is composed mostly of rock or water, respectively. It receives on average 40% more light from its parent star than Earth from the Sun, making it hotter. In comparison, Venus receives 90% more light from the Sun than Earth. We do not know the properties of the atmosphere of Gliese 163c but, if we assume that it is a scaled up version of Earth’s atmosphere, then its surface temperature might be around 60°C. Most complex life on Earth (plants, animals, and even humans) are not able to survive at temperatures above 50°C, however, plenty of extremophilic microbial life forms can thrive at those temperatures or higher.

The detection of potential habitable exoplanets is pacing up. There are now six including the debated Gliese 581g, most of them detected just in the last year. Four of these bodies, Gliese 581d, Gliese 667Cc, Gliese 581g, and now Gliese 163c are around red dwarf stars (M-star). HD 85512 is around a K-star (a middle star between the smaller red dwarfs and the Sun). Only Kepler-22b is around a Sun-like star (G-star). All of these planets are bigger than Earth but still considered potentially habitable, at least to simple life forms. Scientists are trying to construct better ground and space observatories in the next decades to be able to detect smaller worlds, those more resembling Earth. The Habitable Exoplanet Catalog of the Planetary Habitability Laboratory @ UPR Arecibo (phl.upr.edu), which was not involved in the discovery, now includes and ranks Gliese 163c as number five in its main list of best objects of interest for life.

The potential for habitable planets around red dwarf stars has been and issue of much debate. Tidal effects on the planets around these stars might cause extra surface heating or even tidal locking (always giving the same face to its parent star). Also, these stars are more active and their stellar wind might erode planetary atmospheres much faster. These factors might preclude the potential for life on smaller planets but not for planets with thicker atmospheres, something expected for superterran planets. Our Solar System lacks an example of a superterran. Its eight planets are either the smaller terrestrial kind, like Earth, or the larger gas giants, like Jupiter. Understanding superterrans around red dwarf stars, a non Sun-like star, just adds to the challenge of assessing their habitability.

The NASA Kepler Mission has detected about 27 potential habitable exoplanets candidates out of their over 2,300 exoplanets that are waiting to be confirmed. Some of these bodies seem very Earth-like. Unfortunately, they are much farther away from us than Gliese 163 and it will be nearly impossible to determine if they are really habitable worlds by future observations.

However, the statistical analysis of Kepler data suggests that these planets are very common in the galaxy. Therefore, many more Earth-like worlds are waiting to be discovered in our solar neighborhood too, such as Gliese 163c.

The new exoplanets around Gliese 163 were discovered by the European HARPS team led by Xavier Bonfils from the UJF-Grenoble/CNRS-INSU, Institut de Plane ́tologie et d’Astrophysique of Grenoble, France. Other participating scientists are from France, Germany, Portugal, Switzerland, and Belgium. Gliese 163c was announced by team member Thierry Forveille from the Observatoire de Grenoble during the International Astronomical Union session Formation, Detection, and Characterization of Extrasolar Habitable Planets from August 27th to 31st, 2012 in Beijing, China. A paper was submitted to the scientific journal Astronomy & Astrophysics.

The Daily Galaxy via IAU and http://obswww.unige.ch/Instruments/harps/

Comments

[Kris]

I have been thinking, Shouldn't the expansion of the star into a red giant as it leaves the Main Sequence incinerate any close-orbiting planets or other such matter? Then I realized I was confusing red dwarf with white dwarf, and I had never looked into what a red dwarf actually was. So after a bit of Googling and Wikipedia searches I found the entry on red dwarfs in the latter publication.

I did not know red dwarfs more efficiently burn their nuclear fuel due to convection and that they shine happily for 100s of billions of years, and therefore no one knows what happens to them when they burn all their fuel.

But finding that out excited me, because if there are exoplanets in a red dwarf's habitable zone, life would potentially have 100s of billions of years to evolve, and Bog only knows what kinds of life forms might be created over that long period of time—perhaps many species of intelligent life might evolve independently given the opportunity.

That also means life may evolve on a habitable exoplanet well after the expansion of the universe has left its parent star all alone in its region of space.

A sci-fi writer has a lot of material to work with here.

[Cassandra]

So -

What happens when scientists actually find a planet that strongly appears to have life - and it is out of reach? Too far away to reach in a human life span by current technology, and technology to get there faster - too far away in terms of development, for anyone living to see?

What will be the social and psychological impact on a generation or several of researchers who are told "you'll never know, you cannot know, one way or the other"?

[Digbijoy Nath]

Cassandra

Then we know for sure that we are NOT along in this cosmos, which I would say is perhaps one of the biggest discoveries of our species. The question is, is communication with ETs more important than proving/knowing for sure that ETs exist ?

Socially and psychologically, there'd be many changes which we can't predict precisely now. We would perhaps believe that life is commonplace in universe, and that we, humans, or this earth- are NOT special. Religious leaders & fanatics might put this discovery to good or bad use, we don't know.

[John]

Digiboy and Casssandra....It may well be the unifying knowledge that brings us togehter as a species. Only when we unite under a common goal will we be able to reach that far away. We have to put the religious nonsense away and not let it block us from our potential.

[Kris]

Well said John.

P.S. I'm not the Kris above.

[Alun]

What happens when there is some level of confirmation of life on exo-planets/ Europa, Titan, etc is this. (Firstly it need to be conclusive, that could take a while and be debated for an age.

People like us care but the world pays attention for maybe a few weeks and then carrys on just the same, fighting over resources breeding towards 9 billion despite the fact we can't cope/ feed everyone now. I can't see a pround change but a concern over who might win X factor. Sadly to most people it has no meaning as it's just not part off their life.

It might change religon but then that was probably said of most events of major signifcants (confimation of the higg boson for example has had little effect) and yet religon still holds strong across the face off the planet.