Astrophysics_of_Life_secondpart

Astrophysics_of_Life_secondpart - Astrophysics of Life 2:...

Info iconThis preview shows pages 1–6. 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
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Astrophysics of Life 2: Stellar Evolution The Lives and Deaths of Stars The Lives and Deaths of Stars Protostars. These objects radiate energy away in the form of light. That energy comes from gravity – released by contraction. On the Main Sequence, the contraction stops because ravity and internal pressure gravity and internal pressure exactly balance each other. Nuclear reactions occur at exactly the right rate to balance gravity. stars’ mass etermines s luminosity A stars mass determines its luminosity Nuclear reactions slowly convert Nuclear reactions slowly convert H H to to He in the core. He in the core. Newly formed stars are typically: ~91% Hydrogen (H) ~9% Helium (He) In the Sun’s core, the conversion of In the Sun’s core, the conversion of to He ill take 10 billion ears to He ill take 10 billion ears H to He will take ~10 billion years H to He will take ~10 billion years (its Main Sequence lifetime). (its Main Sequence lifetime). Composition of a Sun Composition of a Sun-like star like star What happens when e core Hydrogen is the core Hydrogen is used up? Nuclear reactions stop. ore pressure decreases Core pressure decreases. Core contracts and gets hotter t i l i l- heating overlaying layers. 4H 1He burning moves to a hot “shell.” Post-Main Sequence evolution •4H 1He reactions occur faster than before. •The star gets brighter (more luminous)!...
View Full Document

This note was uploaded on 07/26/2011 for the course AST 2037 taught by Professor Eikenberry during the Fall '08 term at University of Florida.

Page1 / 22

Astrophysics_of_Life_secondpart - Astrophysics of Life 2:...

This preview shows document pages 1 - 6. Sign up to view the full document.

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