Posted by
Hemos
on from the it's-like-the-earth-baby dept.
jrb writes "For the first time, a small planet (i.e. non-gas giant sized) has potentially been found outside the solar system, helped by a gravitational lensing effect that magnified it. The BBC is carrying the full story. "
Just trying to wrap up some points that were being put out here, and maybe answer some questions in the meantime with my intermediate knowledge of astronomy.
Finding this planet, if the evidence leans towards that theory, is a big deal, as so far all we have found arround other systems are very big gas giants. One solar system is really bad for statistical analysis. We could be the fluke of the universe, so just because it happened here doesn't mean it had to happen somewhere else.
Nearly all planet observations, an really all astronomical observations, are objects infered by the bizare behavior of well lit objects. Faint changes in spectrum of a single bright object, means that it is probably a binary system... etc. The best analogy I have heard about astronomy is a goldfish trying to figure out what the world outside its pond is like. It can never go there, but can learn from indirect observations.
I assume that the gravity lensing difference between the two stars can easily be picked out because although they both throw a lot of light, they don't have the same spectrum, and probably not even the same redshift. You can then subtract out the closer star because you very carefully observed it when there was nothing significant behind it.
I don't claim to be an expert on such issues, but hopefully someone got something from my little rant here.
-- There is no silver bullet. Plus, werewolves make better
neighbors than zombies or vampires anyway.
Having been lucky enough to do a literature review on this topic recently (as part of my 3rd year u/g course) I can clear up a couple of issues;
The method used works as follows; when gravitational field of the planet warps the space around it, any light from the star that might otherwise have 'missed' the telescope/eye/pinhole camera (!) would be 'bent' back to the aforementioned instrument.
Hence we do _not_ see the planet, rather the effect of the planet on a star which is how all extrasolar planet detection methods (except one which has failed to date) work.
We have no instruments capable of resolving a planet, but NASA & ESA both havbe projects that in 2020-2060 will be able to do so at IR frequencies. Hence the BBC picture is wrong. All it pointed out was the star.
This method is not repeatable, since it relies on a chance that a background star acts as the source and the planet in orbit around an unseen star all line up for us.
You might think, 'doesn't the planet star lens the background one?' - it does! The additional blip caused by the planet on the light curve is what gives it away.
The typical distance to the background star (usually in the galactic plane) is 100 parsecs, the planet's parent star is usually half this distance for geometric reasons.
Hence it's really far away! We can tell virtually nothing about the planet apart from it's mass (which won't help diffrentiate between tiny gas giants and big terrestrial types).
If anyone want's more info (or even <gasp> a copy of my lit review, written for an intelligent person) then email me. Dosvidania tovarish!
-- --
Thus conscience does make cowards of us all - Hamlet
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Just trying to wrap up some points that were being put out here, and maybe answer some questions in the meantime with my intermediate knowledge of astronomy.
I don't claim to be an expert on such issues, but hopefully someone got something from my little rant here.
There is no silver bullet. Plus, werewolves make better neighbors than zombies or vampires anyway.
The method used works as follows; when gravitational field of the planet warps the space around it, any light from the star that might otherwise have 'missed' the telescope/eye/pinhole camera (!) would be 'bent' back to the aforementioned instrument.
Hence we do _not_ see the planet, rather the effect of the planet on a star which is how all extrasolar planet detection methods (except one which has failed to date) work.
We have no instruments capable of resolving a planet, but NASA & ESA both havbe projects that in 2020-2060 will be able to do so at IR frequencies. Hence the BBC picture is wrong. All it pointed out was the star.
This method is not repeatable, since it relies on a chance that a background star acts as the source and the planet in orbit around an unseen star all line up for us.
You might think, 'doesn't the planet star lens the background one?' - it does! The additional blip caused by the planet on the light curve is what gives it away.
The typical distance to the background star (usually in the galactic plane) is 100 parsecs, the planet's parent star is usually half this distance for geometric reasons.
Hence it's really far away! We can tell virtually nothing about the planet apart from it's mass (which won't help diffrentiate between tiny gas giants and big terrestrial types).
If anyone want's more info (or even <gasp> a copy of my lit review, written for an intelligent person) then email me. Dosvidania tovarish!
-- Thus conscience does make cowards of us all - Hamlet