Kepler 22b

So I follow Kepler on Facebook and I have the Exoplanet app for my iPad.  And as previously blogged about, I love all types of stellar phenomenon.  

The Kepler project detects planets by watching stars continuously and noting when the stars dim and for how long and how often.  This allows the detection of the planets.  The Kepler project is looking at a large patch of stars in a small area of the Cygnus constellation.  There are a few difficulties for this detection.  First the planet must cross the star I between us for the program to detect it.  Second telescope would have to be able to detect the variance.  The further the distance of the star the harder it is to detect a variance, the smaller the planet, the smaller the reduction of the brightness of the star.  Luckily most stars shine at a constant luminosity and our detection of the changes in this range is pretty good (saying that as an amateur, I don't know how good the telescope is). 

Kepler will not announce a find every time it sees a blip.  The second time it sees the same intensity of a blip, it will be able to determine the orbital period and thus the distance and because of the distance, the size of the planet, radius not mass.  It will use the orbital period to predict when the planet will next eclipse the star.   When the prediction is confirmed, the planet is released to the public.

The star is a little smaller and less luminous than out own which may simply mean it is younger than out own or that it is smaller.  The star has a metallicity similar to our own, which means that it has a proportion of non hydrogen and helium as our sun.  So this means that it will have about the same amount of raw materials for planets as our own solar system.  

Kepler 22b is about 2.38 earth radi in size, has a year of about 290 days, and is in the habitability zone of the star.  The distance from the star means the average temperature of -11C.  With an atmosphere, the temperature of 22C.  But Kepler does not detect mass, so the really neat stuff about a planet cannot be determined, but if one makes a few assumptions, it can be done.

If the planet has a density similar to our planet, what would it be like?  There are gravity calculators on the Internet and if you don't now it already so is the formula for the volume of a sphere.  Using these formula I get the planet has a mass 56 times that of earth and a gravity of about 9 Newtons, we would all weigh less than on Earth.  The escape velocity of the planet would be close to the ability to hold water molecules.  Meaning that it would be likely a water filled world like our own.  But the problem is that at 56 times the Earth's mass, that is more mass than all the terrestrial planets and the moons of all the planets combined, so I think it likely that it is in this case a water world.

The problem of the water world theory is that it that would lower the density of the planet a lot and that would reduce the surface gravity enough that water would then be able to escape the gravity of this planet.  So after that, I am forced to conclude that it has to have a very large rocky core and the rest is made up out of a surface of ocean that is very deep.

Unless, the planetary core is very dense and this is a very small gas giant, very very small, or a stellar remaint, or even a brown dwarf.  A lot is pending on what the mass of this planet is.  Very likely all that we will be able to do is rule out that it is very heavy and thus not a stellar remaint, with current technology.

So much fun!