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Bartholomew
09-26-2008, 09:02 AM
http://www.msnbc.msn.com/id/25191635/


A trio of planets called super-Earths has been spotted orbiting a sunlike star, astrophysicists announced Monday at an international conference in France.

Super-Earths are more massive than Earth but less massive than Uranus and Neptune. Spotting true Earth-sized planets is challenging with current technology, but the presence of super-Earths suggests finding a world like ours is just a matter of time, researchers say.

So cool! Especially since I've got a short story that revolves around just such a planet.

L M Ashton
09-26-2008, 06:36 PM
Very cool! But I'm a little... Confused.
The smallest of the trio weighs in at 4.2 Earth masses and orbits HD 40307 every 4.3 Earth days, while the largest, with a mass 9.4 times that of Earth, has a 20.4-day orbit. The middleweight is 6.7 Earth masses and makes a 9.6-day-long trek around the star.That's, uh, awfully fast. Given that these discoveries were by a European team, was there perhaps a translation error? Or are they just that close to their sun? If so, I would have thought they'd either a. get sucked into the star's gravity b. be far far far far too hot to be inhabitable or c. I'm missing something completely.

Albedo
09-26-2008, 07:58 PM
Nah, it's correct. Most of the extrasolar planets we've found have comparatively tiny orbital periods compared even to Mercury in our system. Some, like the 'hot Jupiters', are so close that their atmospheres are incandescent. I think this is because the techniques we use to find these planets work by indirect observation of the star's wobble, etc. and currently we can't resolve something as small as an Earth-size planet in a more distant, life-supporting orbit. We will one day, though. I hope it doesn't turn out that real Earths are rare, and ours only ended up in a life-supporting orbit by cosmic accident. Though that would go some way towards explaining the Fermi paradox.

Sophia
09-26-2008, 11:58 PM
If so, I would have thought they'd either a. get sucked into the star's gravity b. be far far far far too hot to be inhabitable or c. I'm missing something completely.


The technique they're using has a built-in selection effect, where it is most likely to detect massive planets orbiting close to their parent star. I think the article is a little misleading in that by referring to 'super-Earths' without a clear explanation of the term, makes people think that the planets are Earth-like, when its only a reference to their mass being closer to that of Earth than say that of Jupiter. A planet that is in the habitable zone of any stellar system, which is defined as where water can exist as a liquid upon a planet's surface, would be much farther out than where current technology can really detect them.

L M Ashton
09-27-2008, 05:09 AM
Albedo, thanks for the explanation and the reassurance that I'm not nuts. Well, about this, anyway. :)

ElaraSophia, I completely agree. I gathered - after the fact - that superearth refers to mass of the planet only and not on any other factors involving the inhabitability of the planet.

Bartholomew
09-27-2008, 11:21 AM
I just assumed they were calling them Super Earths because they weren't Gas Giants. :)

JimmyB27
10-03-2008, 02:04 PM
I just assumed they were calling them Super Earths because they weren't Gas Giants. :)
I thought it was because they wore their underpants over their trousers.

Bartholomew
10-13-2008, 12:45 AM
I thought it was because they wore their underpants over their trousers.

Don't forget the <SE> emblem. SuperEarths, saving the cosmos one deadly mile-wide asteroid at a time.

Sarpedon
10-16-2008, 08:43 PM
A gas giant probably couldn't exist so close to their parent stars.

It has to be rocky, or it would evaporate.

Like Mercury. No atmosphere to speak of.

lpetrich
10-16-2008, 11:56 PM
Wikipedia's contributors have a nice article about HD 40307 (http://en.wikipedia.org/wiki/HD_40307).

From the numbers on that star and its planets, I can estimate the average surface temperatures of its planets with the help of the Stefan-Boltzmann law:

Mars: -40 C
Earth: 15 C (reference)
Venus: 66 C
Mercury: 191 C

Those planets:
b: 650 C
c: 430 C
d: 270 C

So they would be hotter than Mercury, and would not have any liquid water on their surfaces.

Bartholomew
10-17-2008, 03:48 AM
Wikipedia's contributors have a nice article about HD 40307 (http://en.wikipedia.org/wiki/HD_40307).

From the numbers on that star and its planets, I can estimate the average surface temperatures of its planets with the help of the Stefan-Boltzmann law:

Mars: -40 C
Earth: 15 C (reference)
Venus: 66 C
Mercury: 191 C

Those planets:
b: 650 C
c: 430 C
d: 270 C

So they would be hotter than Mercury, and would not have any liquid water on their surfaces.

Cool!

Er, I mean, uh...

Revelationz
11-17-2008, 03:19 PM
The more we look for a planet like ours the more disappointed we become.

Many solar systems tend to be rather unkind to the conditions suitable for life. Then, in each galaxy you have a habitable zone, which is a very small area of a galaxy where a solar system like ours would be able to create life.

Basically, the universe is like a very big roulette table. Its like the universe was created to make as many galaxies as possible with as many solar systems as possible so that perhaps one, just one, would result in life. COnsidering how chaotic it is out there beyond our little thin atmosphere, whether you're a religious person or not, life coming about here even if nowhere else was a miracle.

And even if we did find life elsewhere, odds are that it won't be intelligent. About the best we could ever hope for is to find microscopic life.