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Alrighty then. Last time I left off at... saying a 0.4 metre aperture is insufficient for directly detecting extrasolar planets (exoplanets? that term is much more convenient to type and to say so why not use it instead?), even though it is sufficient to resolve the components. One problem: Magnitude 27 is very very dim. 6 is generally considered the cut-off for what can be seen with the unaided human eye (though many people's eyes are better or worse and light pollution can signifcantly reduce what is visible), so while the star is visible to the unaided eye the planet is more than ten thousand times dimmer. So we need to make sure our telescope is gathering sufficient light to even detect the planet.
*runs over to text-bearing bookcase*
Yes, this is basic stuff, and yes, I did have to look some up. In fact I was rather getting off on the wrong foot. Y'see, although a larger aperture helps to gather more light at once, dimmer objects can still be seen with a smaller scope if the integration time is increased. Doesn't work if one is observing with their own eyes - not being able to adjust exposure time and all. Actually, oh dear, I am rather afraid I might be spouting nonesense now. But I will correct my own errors as soon as I may, and sooner if they are pointed out to me. This is the kind of thing that will get one embarrassed looking back at the bloggings of their youth in years to come (well, actually actually what will really be embarrassing are the side musings I have not posted this past week on behalf of the illusion of focused discipline but that will just have to wait). Let us just go instead to the matter of contrast.
Oh, okay. (At least) One more diversion first. I find it interesting that an Earth-equivalent planet has an absolute magnitude only a little less than a Jupiter-equivalent (28.1[Woolf & Angel 1998] vs. 27 [Marcy & Butler 1998]). Being closer to the host star will make it still harder, though. Aaaanyway-
We already have telescopes capable of detecting such faint objects (e.g.), the difficulty is preventing the image from being washed out by the overwhelmingly brighter nuclear furnace sight right next door. Repeating myself enough yet? It is a sign of lack of thorough knowledge and clarity of thought. But if I work hard and study much that may improve.
What we need to do is find a way to suppress unwanted illumination so that what we are after is not obscured. Lessee, quote:
*runs over to text-bearing bookcase*
Yes, this is basic stuff, and yes, I did have to look some up. In fact I was rather getting off on the wrong foot. Y'see, although a larger aperture helps to gather more light at once, dimmer objects can still be seen with a smaller scope if the integration time is increased. Doesn't work if one is observing with their own eyes - not being able to adjust exposure time and all. Actually, oh dear, I am rather afraid I might be spouting nonesense now. But I will correct my own errors as soon as I may, and sooner if they are pointed out to me. This is the kind of thing that will get one embarrassed looking back at the bloggings of their youth in years to come (well, actually actually what will really be embarrassing are the side musings I have not posted this past week on behalf of the illusion of focused discipline but that will just have to wait). Let us just go instead to the matter of contrast.
Oh, okay. (At least) One more diversion first. I find it interesting that an Earth-equivalent planet has an absolute magnitude only a little less than a Jupiter-equivalent (28.1[Woolf & Angel 1998] vs. 27 [Marcy & Butler 1998]). Being closer to the host star will make it still harder, though. Aaaanyway-
We already have telescopes capable of detecting such faint objects (e.g.), the difficulty is preventing the image from being washed out by the overwhelmingly brighter nuclear furnace sight right next door. Repeating myself enough yet? It is a sign of lack of thorough knowledge and clarity of thought. But if I work hard and study much that may improve.
What we need to do is find a way to suppress unwanted illumination so that what we are after is not obscured. Lessee, quote:
The criterion for resolving and detecting objects of enormously different intensity needs some discussion. The planet does not have to be brighter than the local halo of scattered starlight, but its detection does require that, at a minimum, the random fluctuations in the halo due to photon noise be smaller than the planet signal.Well. Pause for thought. And... questions? ^_^
