ASTR 114 Lecture Notes - Lecture 14: Annie Jump Cannon, Stellar Classification, Binary Star

• School: Binghamton University
• Department: Astronomy
• Course: ASTR 114
• Professor: Christopher A.Taylor

Document Summary

Annie jump cannon and the "calculators" at harvard laid the foundation of modern stellar classification. Measuring stellar masses in binary stars: orbit of binary star system depends on strength of gravity. Center of mass: balance point of the system both masses equal => center of mass is in the middle, ra = rb. The more unequal the masses are, the more it shifts toward the more massive star (the less massive stars always remain farther from the center of mass and move faster) Visual binary systems: both stars can be seen directly, and their separation and relative motion can be followed directly (can be measured directly) Spectroscopic binary systems: we determine the orbit by measuring doppler shifts. Eclipsing binary systems: we can measure periodic eclipses (at points light becomes dimmer. Estimating stellar masses: m1 +m2= a3/p^2 where a=separation and p=period in years. Important formula: m2(r2/r1) + m2 = a3/p2 -or- m2(v2/v1) + m2 = a3/p2.