Absalom wrote:Arioch wrote:GeoModder wrote:Taken this image into account, and the data turns out to be correct, it starts to look like the 4,3 E-m planet might turn out to be Venus-like in its atmospheric density.
I would think that such a massive planet would have a very dense atmophere just from the higher gravity alone. Unfortunately, even though super-Earths appear to be very common in other systems, we don't have any in our solar system for reference.
I've been told that it's thought that if Earth had more time before the Sun swept the nebula away, then it would have become a gas giant. I wouldn't be surprised if the details are so finicky with these things that you can only know how it'll turn out be looking at the results.
Erm, no. As far as we know Earth has never been far enough from the Sun to give the lighter elements a chance to coalesce on its proto-planetary atmosphere before the solar wind blew them off. Besides, the composition of our current atmosphere is sufficient prove for this. If not, Earth's atmosphere would've been mostly hydrogen.
For instance, most of the water Earth holds is said to come from cometary impacts.
Victor_D wrote:I know, but AFAIK the main asteroid belt is only possible due to the disruptive influence of Jupiter. Tau Ceti doesn't seem to have one, and the super-earths likely don't have enough pull to prevent the material between them from coalescing. I hope
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The model they used to sift through the noise to find something that might be candidate planets means the farther out from the star you go, the heavier they must be to be detected. So it is at least plausible that a smaller Earth-sized planet in the right orbit between the last two 'detected' planets might remain undetected for the time being.
Well, as I said before, the masses we know of are
minimum masses. Granted this outer planet of Tau Ceti won't have dozens of Earth masses, but its orbit is way closer to Tau Ceti, so it makes more sweeps (and consequently gives more gravitic "pushes") to whatever is approaching the inner system. Also, as Arioch's linked picture shows, the orbit where at Tau Ceti a planet would receive the equivalent of Earth's received sunlight is not that far out of the 4,3 E-m planetary orbit. So to have an Earth-like habitable planet on an orbit between f and e, we
need a planet with more then one E-m. And the higher the mass, the more likely it would already have been spotted in the data. Especially since five more "signals" have already been detected.
Arioch wrote:I would think that such a massive planet would have a very dense atmophere just from the higher gravity alone. Unfortunately, even though super-Earths appear to be very common in other systems, we don't have any in our solar system for reference.
Yes, of course. But to give you a comparison from our system, Uranus (the lightest giant) has a total mass of about 14.5 E-m. Only about 0.55 E-m of that is thought to be part of its solid core. It all depends on composition of the planetary core (and subsequently in what part of a star system it formed).