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View Full Version : Discussion: Will We Find Super Earths?



Fraser
2005-Jul-13, 03:55 PM
SUMMARY: As techniques and equipment for finding extrasolar planets improve, astronomers are finding planets with smaller masses. First it was Jupiter-sized planets and larger, then Saturn-sized planets, and now Neptunians. But could these Neptune-mass planets actually be terrestrial planets, made of rock instead of gas and ice? Unlike Neptune and Uranus, these planets orbit very close to their host star. Astronomers will need to find one that transits in front of its host star to they can determine its density, to know if it's rock, ice or gas.


View full article (http://www.universetoday.com/am/publish/find_super_earths.html)

What do you think about this story? Post your comments below.

Guest
2005-Jul-13, 04:23 PM
The gas giants all display violent atmospheric dynamics; high winds and strong storms would no doubt decrease the chances of a planet's habitibility. Is this meteorlogical behavior a result of the size of the planet? I'm going to look into it after class, but if anyone knows if a planet's size is directly related to the energy of it's atmospheric 'events', write a little note here. This might be another factor in establishing an upper limit to the size of habitible planets.

John L
2005-Jul-13, 07:14 PM
Guest,

Even though a planet the size of Saturn or Jupiter could not support life, it may have many large terrestrial moons that can.

As for the story, I don't think we're close enough yet.

lswinford
2005-Jul-13, 07:16 PM
And why do "gas giants" have to be icy? With recent stories of large planets with dense atmospheres orbiting close to their stars, it seems we need to differentiate our discussions between colder and hotter worlds that have deep atmospheres. While we are therefore in need of convenient expressions, I suggest 'cold gas' and 'hot gas' planets, just leaving the 'giant' part to be assumed since I doubt we would be viewing, much less discussing, observable small rocky worlds any time soon.

aeolus
2005-Jul-13, 07:27 PM
Originally posted by John L@Jul 13 2005, 07:14 PM
Guest,

Even though a planet the size of Saturn or Jupiter could not support life, it may have many large terrestrial moons that can.

As for the story, I don't think we're close enough yet.
I was more just curious about the possible direct relation between size of a planet and intensity atmospheric activity. Of course such large planets wouldn't be habitible due to gravity issues.

Is the reason why the GGs have such high winds etc due to their size, or is it their composition/temperature/unknown?

alainprice
2005-Jul-13, 11:19 PM
I'm guessing it's their composition.

Most gas giants are very oblate(look at saturn), with polar diameters considerably smaller than their equitorial diameters. Don't forget a day on Jupiter or Saturn is only 10 hours long. Plus who knows what kind of core reaction is going on.

Does anyone know how much heat is generated by the gas giants, while neglecting heating from the sun?

lswinford
2005-Jul-14, 01:32 PM
alainprice, not me, but I know that when the notes were made in the 1960-1970's that there seemed to be more energy emitted than received that some started discussing what a failed star would look like. Since we have better data and better data collection tools and methods I would look for newer stories rather than old, ten and no more than fifteen years old. Here's a place that might be a good starting spot to mine for reference directions: http://www.jupitertoday.com/

GOURDHEAD
2005-Jul-14, 01:48 PM
Is the reason why the GGs have such high winds etc due to their size, or is it their composition/temperature/unknown? My guess is that it is a combination of their rotational speed, temperature and temperature distribution, and magnetic field interaction with their magnetic environment.

Nereid
2005-Jul-21, 09:01 PM
"Guest" asks a particularly interesting question - to what extent are 'atmospheric' phenomena in planets with extensive gaseous atmospheres primarily the result of 'planetary' inputs (cf such things as 'solar winds' or 'solar irradiation')?

Today, the answer surely is "we don't know"; but it would seem that the deeper you go into the atmosphere, the less important are factors such as the number and energy of photons incident on the top layers of the atmosphere from the 'sun'.

At least in the 'short' term; if the time scale of the question is broadened to Myears, or Gyears, then how fast the central star can strip the atmosphere becomes of crucial importance.

An entirely different question is what are the lifetimes of (GG) planetary orbits? While the internal state of the planet may affect such lifetimes to a minor extent, more likely are orbital dynamics issues, to do with how many other planets there are, in what orbits, with what masses, etc.

The intial exo-planet discoveries were in a region of parameter-space that was unexpected. Still today the region of parameter-space that has been explored with even the crudest level of completion is tiny to utterly trivial.

Best we wait until we have a whole lot more data on what *real* planetary systems are like - statistically (mean, ranges, etc) - before indulging in too much speculation?