ASTR 1150 Lecture Notes - Lecture 4: Lalande 21185, Dynamical Parallax, Proper Motion
Document Summary
Astr 1150 - lecture 4: the solar neighbourhood + the interstellar medium. Seen as a single star to the unaided eye. Nearby stars are still extremely far away. 3ly, which is equivalent to roughly 30 trillion km, (vancouver to kamloops 100 billion times) Furthest any spacecraft has ever travelled is 18. 5 billion km (only 1/10,000th of the way to the closest star and that took 35 years) How do we know the distances to these nearby stars. Using the apparent motion of an object relative to a fixed background to determine that object distance. The distance to nearby stars can be measured using heliocentric parallax (also called orbital parallax) Parsec(pc): distance to an object with a parallactic half the angle of 1 arcsecond. Light years(ly): the distance light travels through space in one year. Astronomical unit(au): the average distance from each to the sun. D= distance to a star in parsecs.
