chapter10 - The Sun Our star Nearest star Only star whose...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
The Sun: Our star • Nearest star – Only star whose structure can be seen in detail! • R ± ~ 700,000 km = 109 Re • M ± = 1.99 x 10 30 kg = 332,000 Me = 99.9% M solarsystem Mean density = M/ (4 π R 3 /3) = 1410 kg m -3 – Lighter than the Earth! • Standard unit for measuring properties of other stars, even galaxies
Background image of page 1

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

View Full DocumentRight Arrow Icon
What’s the Sun made up of? • Measure composition from spectra (absorption lines) 0.05 0.05 S 0.14 0.14 Fe Fe 0.09 0.09 Si Si 0.06 0.06 Mg Mg 0.16 0.16 Ne Ne 0.8 0.8 O 0.09 0.09 N 0.2 0.2 C 25 25 He He 73 73 H % by mass % by mass Very Very different different from Earth! from Earth!
Background image of page 2
What sets the Sun apart from What sets the Sun apart from Planets? Planets?
Background image of page 3

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

View Full DocumentRight Arrow Icon
What sets the Sun apart from What sets the Sun apart from Planets? Planets? Radiates energy much more than any planet Radiates energy much more than any planet Not just reflected energy, but very strong intrinsic Not just reflected energy, but very strong intrinsic energy sources energy sources nuclear reactions nuclear reactions Luminosity = total amount of energy emitted Luminosity = total amount of energy emitted per second in all directions per second in all directions Flux = Energy/area/time Flux = Energy/area/time Energy/m Energy/m 2 /s /s Flux = luminosity/ (4 Flux = luminosity/ (4 π r r 2 ) Flux Flux at earth = 1400 w/ at earth = 1400 w/ m 2 L ± =3.8 =3.8 x 10 10 26 26 W W
Background image of page 4
Is it on FIRE? Why does the Sun Shine?
Background image of page 5

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

View Full DocumentRight Arrow Icon
Is it on FIRE? Luminosity ~ 10,000 years Chemical Energy Content
Background image of page 6
Is it on FIRE? … NO! Luminosity ~ 10,000 years Chemical Energy Content
Background image of page 7

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

View Full DocumentRight Arrow Icon
Is it CONTRACTING?
Background image of page 8
Gravitational Potential Energy Is it CONTRACTING? ~ 25 million years
Background image of page 9

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

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/10/2011 for the course SCHC 115 taught by Professor Kulkarni during the Spring '09 term at South Carolina.

Page1 / 62

chapter10 - The Sun Our star Nearest star Only star whose...

This preview shows document pages 1 - 10. Sign up to view the full document.

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