Coming to a solar system near you… super-Earth!

Aug 08, 2011 By Tammy Plotner
Planetary system of HR 8799 imaged by Marois et al (2010). The central star is of spectral type A with a mass of 1.5 solar-masses at a distance of 128 light-years from the Sun. The planets have the masses of Mb = 7MJ , Mc = Md = 10MJ , and Me = (7?10)MJ , with semimajor axes of 68, 38, 24, and 14.5 AU, respectively. Figure with the permission of NPG.

It is our general understanding of solar system composition that planets fall into two categories: gas giants like Jupiter, Saturn, Neptune and Uranus… and rocky bodies that support some type of atmosphere like Earth, Mars and Venus. However, as we reach further into space we’re beginning to realize the Solar System is pretty unique because it doesn’t have a planetary structure which meets in the middle. But just because we don’t have one doesn’t mean they don’t exist. As a matter of fact, astronomers have found more than 30 of them and they call this new class of planet a “Super-Earth.”

“Super-Earths, a class of planetary bodies with masses ranging from a few Earth-masses to slightly smaller than , have recently found a special place in the exoplanetary science.” says Nader Haghighipour of the Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii. “Being slightly larger than a typical terrestrial planet, super-Earths may have physical and dynamical characteristics similar to those of Earth whereas unlike terrestrial planets, they are relatively easier to detect.”

Having a super-Earth in the neighborhood opens the avenue towards habitability. Chances are planets of this type have a dynamic core and are able to maintain a type of atmosphere. When combined with being within the of a host star, this raises the bar towards possible life on other planets.

“It is important to note that the notion of habitability is defined based on the life as we know it. Since Earth is the only habitable planet known to humankind, the orbital and physical characteristics of Earth are used to define a habitable planet.” says Haghighipour. “In other words, habitability is the characteristic of an environment which has similar properties as those of Earth, and the capability of developing and sustaining Earthly life.”

But being a super-Earth means that there is a lot more going on than just being in the zone. To qualify it must meet three requirements: its composition, the manifestation of plate tectonics, and the presence of a magnetic field. For the first, the presence of liquid water is a high priority. In order to determine this possibility the values of its mass and radius have to be known. To date, two super-Earth planets for which these values have been determined – CoRoT-7b and GJ 1214b – have given us fascinating numerical modeling to help us better understand their composition. Plate tectonics also plays a role through geophysical evolution – just as the presence of a magnetic field has been considered essential for habitability.

“Whether and how magnetic fields are developed around super-Earths is an active topic of research.” notes Haghighipour. “In general, in order for a to be in place around an Earth-like planet, a dynamo action has to exist in the planet’s core.”

Last, but not least, comes an atmosphere – the “presence of which has profound effects on its capability in developing and maintaining life.” From its chemical properties we can derive the “planet’s possible biosignatures” as well as the chemicals which formed it. Atmosphere means environment and all of this leads back to being within a habitable zone and of sufficient gravity to keep atmospheric molecules from escaping. Says Haghighipour, “It would not be unrealistic to assume that super-Earths carry gaseous envelopes. Around low-mass stars, some of such atmosphere-bearing super-Earths may even have stable orbits in the habitable zones of their host stars.”

Has a super-Earth been detected? You betcha’… and studied right down to its spectral signature. “The recently detected super-Earth GL 581 g with its possible atmospheric circulation in the habitable zone of its host star may in fact be one of such .” says Haghighipour. “More advanced telescopes are needed to identify the biosignatures of these bodies and the physical and compositional characteristics of their atmospheres.”

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User comments : 15

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Zarabtul
1 / 5 (6) Aug 08, 2011
Did anyone think that as some wormholes are a very tight center and others are not allowing in and out showing you what you need.
xNico
1.7 / 5 (3) Aug 08, 2011
Why are people and scientists so ignorant and think life can only exist on planets that are exactly like earth? Pathetic, and we call ourselves an intelligent species.
Thecis
not rated yet Aug 09, 2011
It is not really that pathetic. As they said in Star-Trek: "It's life Jim but not as we know it."

As physics is alike throughout the universe (relativity) also chemistry should act somehow the same as on earth because this is actually just physics (interactions between atoms/molecules). Also, it has been shown that simple molecules can be formed in outer space (even simple amino acids!).
Is it still so hard to believe that most life should act the same on earth? There are enough theories that Silicon based life forms are possible but those have not yet be proven or even made assumable (i think that would be key to make it assumable, since proving it would mean we are also definite about not being the only one).

In my opinion it is a fair starting point with enough evidence that supports the claim. We should keep an open mind though...
Jordian1
1 / 5 (1) Aug 09, 2011
It's ridiculous to assume there isn't other life out there. There are hundreds of billions of stars in the milky way. Even if earth is 1:1,000,000,000 (and most estimates say 1:1,000,000)
It still means there are hundreds of earths. Are we so arrogant to believe that we are the only thing this galaxy has produced?
Thecis
not rated yet Aug 09, 2011
Frankly, I am almost certain that there is other life given the exact same rationale.

The real question is what it will look like. Will it look like on earth? Probably not.

Will it be carbon based? Most likely, given the above rationale.

But what if we are indeed unique? Or what if not-condensed energy is the most occuring form of life (no-mass containing organisms)? What if we were indeed an anomoly? Have anyone ever thought about the not so obvious or not-logical conclusions?
xNico
not rated yet Aug 09, 2011
Also there was an article I read on here yesterday, which was about life on earth only being possible due to building blocks (amino acids) arriving here through meteorites. If that is indeed the case, what are the chances of Earth being the only planet those building blocks have traveled to. Who's to say that there aren't other building blocks not known to us.
xNico
1 / 5 (1) Aug 09, 2011
It is not really that pathetic. As they said in Star-Trek: "It's life Jim but not as we know it."

As physics is alike throughout the universe (relativity) also chemistry should act somehow the same as on earth because this is actually just physics (interactions between atoms/molecules). Also, it has been shown that simple molecules can be formed in outer space (even simple amino acids!).
Is it still so hard to believe that most life should act the same on earth? There are enough theories that Silicon based life forms are possible but those have not yet be proven or even made assumable (i think that would be key to make it assumable, since proving it would mean we are also definite about not being the only one).

In my opinion it is a fair starting point with enough evidence that supports the claim. We should keep an open mind though...

What about the event horizon? What about other galaxies millions of light-years away? We can not just assume the laws of physics work the same.
emsquared
not rated yet Aug 09, 2011
More advanced telescopes are needed to identify the biosignatures of these bodies and the physical and compositional characteristics of their atmospheres.

This is why the death of Hubble and it's successor is so saddening to me. Optics is the cheapest way for us to explore the universe. It seems to me once we get some better propulsion figured out, we should be sending out Hubble or JWST/Voyager hybrids on paths near some likely solar systems to get some closer looks. Who knows what might be discovered through the implementation of multiple, distant perspectives as well.
emsquared
not rated yet Aug 09, 2011
More advanced telescopes are needed to identify the biosignatures of these bodies and the physical and compositional characteristics of their atmospheres.

This is why the death of Hubble and it's successor is so saddening to me. Optics is the cheapest way for us to explore the universe. It seems to me once we get some better propulsion figured out, we should be sending out Hubble or JWST/Voyager hybrids on paths near some likely solar systems to get some closer looks. Who knows what might be discovered through the implementation of multiple, distant perspectives as well.
rwinners
5 / 5 (2) Aug 09, 2011
I don't care to think about how much exercise I'd have to do just to be able to crawl on a planet like this!
Thecis
4 / 5 (1) Aug 10, 2011
@xNico
We can not only just assume physics work the same throughout the universe, it has already been proven and although contradictions seem to be present, the theory that describes this (the theory of relativity of Einstein) still stands. The special theory of relativity describes that physics remain the same for all motion remaining at the same speed as the second theory describes this for ALL motions.
So like you said, we cannot just assume it..., it was already proven.
Assuming that physics work differently in galaxies far away is just assuming that we are indeed different. No need for that.

I must admit that we do not understand a lot of physics. We know how some things work but we do not understand it. The fact that event horizons are very obscure for us is that we are only at the beginning of describing it. But physics wont change there...
Sinister1811
1 / 5 (1) Aug 14, 2011
If there's Earth-like life on a planet like this, it'd probably be very large and very muscular compared with life on our tiny planet.
444
not rated yet Aug 14, 2011
I think carbon based life found on Earth is probably representative of all life in the universe. Scientists have studied silica chemistry and concluded silica life is unlikely. Hopefully we will one day be able to study life on other planets and see if this is so.
Looking for and studying planets similar to Earth is the best strategy for finding extraterrestrial life.
Jonseer
3 / 5 (1) Aug 15, 2011
".....It is our general understanding of solar system composition that planets fall into two categories: gas giants like Jupiter, Saturn, Neptune and Uranus."

UM what 1960s Textbook did that come from?

More recently there has been a clear line drawn between Jupiter and Saturn and the many times smaller Uranus and Neptune.

Uranus and Neptune are considered to be in terms of size the in-between planets.

The radius of Neptune is approx. the same fraction of Jupiter's radius as is Earth's radius of Neptune's, and Jupiter is approx. 18x as massive as Neptune, just as Neptune is approx. 17x as massive as Earth.

The difference in masses and where they are formed make the similarity in the atmospheres a poor indicator of what their entire composition is like to the core.

And their atmosphere's have more "ices" thus they are called the "Ice Giants" not just simply "gas giants" like Jupiter and Saturn.
Sinister1811
1 / 5 (1) Aug 15, 2011
That may be true, but Uranus and Neptune both have extraordinarily gaseous atmospheres. They don't just consist of ices. Anyone who wants to go ice skating on Uranus and Neptune will be crushed under the high gravity and thick atmospheres of both planets. They are thus more like Jupiter and Saturn than they are Mercury, Venus, Earth and Mars.