PHYS 183 Lecture Notes - Lecture 33: Binary Star, Minute And Second Of Arc, Methods Of Detecting Exoplanets
21 Apr 2018
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Document Summary
Has been known for centuries that distant stars were suns. Obvious in hindsight that planets should be common. Direct detection: see planet directly via imaging. Technologically very hard to detect: only small handful found this way thus far. Indirect detection: observe starlight affected by planet but no the planet itself. Stars are typically 1-10 billion times brighter than the planet: e. g. Jupiter refle(cid:272)ts o(cid:374)l(cid:455) (cid:1004). (cid:1007) (cid:271)illio(cid:374)ths of the u(cid:374)(cid:859)s light: looking for a firefly next to a search light i. e. contrast ratios of 109-1010 at separatio(cid:374)s of (cid:1004). (cid:1004)(cid:1005)(cid:863)-(cid:1005)(cid:863) contrast ratios better at infrared wavelengths but still challenging. Atmospheric blurring distorts images so impossible to see such small separations. Teles(cid:272)ope uses (cid:858)laser guide star(cid:863) to deter(cid:373)i(cid:374)e effe(cid:272)t of at(cid:373)ospheri(cid:272) tur(cid:271)ule(cid:374)(cid:272)e i(cid:374) real time. Corrects stellar images using guide star corrections. Provides near diffraction-limited imaging from the ground: can have more sensitivity as ground based telescope larger than space based.
