NATS 1745 Study Guide - Final Guide: Henry Draper Catalogue, Planetary Nebula, Cecilia Payne-Gaposchkin
25 Apr 2015
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Document Summary
Since parallax decreases with distance & since our baseline is limited, parallax distances can only be measure for nearby stars. There is a limit as to how big of a baseline we can achieve on earth longest baseline we can achieve is the diameter of. Earth"s orbit & thus limits how big of a parallax we can induce from the earth which means only the nearest stars have parallax that is detectable from the earth. Halley"s discovery aided the search for stellar parallax because it gave astronomers a way to identify the nearest stars, and therefore the stars most likely to have detectable parallax. If a star appears bright and has fast motion across the star, it is very likely a nearby star. What is the definition of a parsec? (note: the specific values in km aren"t necessary here). Parsec (pc): the distance (d) of an object with a parallax (p) of 1 arcsecond.
