lecture17

lecture17 - • Calculating Stellar Masses • watch out...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 5/9/08 • Calculating Stellar Masses • watch out for units and equations • Mass-Luminosity Relation • Colors and Temperatures of Stars • Main Sequence • Sizes of Stars DEMO • Two light bulbs have same luminosity • Their flux (apparent brightness) changes depending on their distance to you. Measuring Stellar Masses • The mass of an object is a key detail. • If we can measure an object’s orbit, we know the mass of the object it’s orbiting. – we did this all over the solar system, with moons around planets! • Lucky for astronomers, stars are often in binary systems • Binary stars: a pair of stars that are orbiting around their common center of mass. Binary Stars • If we can distinguish the two stars visually, it’s a visual binary. • We can determine the two masses: • M 1 and M 2 : masses of stars in solar masses • a: semimajor axis, in AU • P: period of orbit, in years M 1 + M 2 = a 3 P 2 Visual Binary Spectroscopic binary • Sometimes we can’t visually distinguish the two stars • But then we look at the spectrum – and we see velocities of two objects! • Since their velocities change (with respect to us) as they orbit each other, the locations of the spectral lines changes Masses and Luminosities • Now we have measured the masses and luminosities of a wide range of stars....
View Full Document

This note was uploaded on 06/11/2008 for the course ASTRO 1 taught by Professor Antonucci during the Spring '08 term at UCSB.

Page1 / 19

lecture17 - • Calculating Stellar Masses • watch out...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online