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piareround
Jul1-10, 09:56 PM
Recently I been reading about exoplanets on wikipedia when I came across a line that caught my idea:

It is possible to estimate the temperature of an exoplanet based on the intensity of the light it receives from its parent star. However, such estimates may be substantially in error because they depend on the planet's usually unknown albedo, and because factors such as the greenhouse effect may introduce unknown complications. A few planets have had their temperature measured by observing the variation in infrared radiation as the planet moves around in its orbit and is eclipsed by its parent star

So I started wondering exactly what did Wikipedia mean by "based on the intensity of light" and later on by "temperature measure by observing the variation in infrared radiation". I mean really how do astronomers and astrophysics find the temperatures of nearby exoplanets even though they are hundreds of parsecs away. Specifically, I really wanted to know the following two things:


1. Where kind I find more through information about theory and concepts behind the transit method of observing exoplanets? Specifically I was curious about the formulas/theory they used.
2. How does one estimate, say to the nearest hundred degrees, a exoplanet's effective temperature when the exoplanet's albedo is unknown?

piareround
Jul5-10, 09:53 AM
To be honest guys, I really am curious in trying to find out more information about how astronomers estimate the temperature of a planet if they don't know the albedo. Any information you all can find would be very helpful

qraal
Jul6-10, 06:25 AM
To be honest guys, I really am curious in trying to find out more information about how astronomers estimate the temperature of a planet if they don't know the albedo. Any information you all can find would be very helpful

Usually things get quiet around here when no one knows the answer. I think the quoted temperatures are for zero albedo, unless there's some evidence otherwise, as getting the necessary NIR data is really hard to do.

qraal
Jul6-10, 06:28 AM
Usually things get quiet around here when no one knows the answer. I think the quoted temperatures are for zero albedo, unless there's some evidence otherwise, as getting the necessary NIR data is really hard to do.

Plus there's been lots of atmospheric modelling to try to estimate albedos in different parts of the spectrum to see if there are observable signatures.

Freshtictac
Jul10-10, 01:35 PM
I have an answer you may not like. Any temperature estimates would be just that, educated guesses. With out actually sending measuring equipment to said Exoplanet there could be no conclusive method for exploring what the temperature would be. Perhaps there is a planet with a similar 93 billion mile buffer between it and it's parent star, but it could contain a larger or smaller molten core that would generate variant effects on the atmosphere of an unexplored planet.

Also, try omitting wikipedia from your forum vocabulary and research.