Astrophysics_of_Life_3

Astrophysics_of_Life_3 - Astrophysics of Life 3: Stellar...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Astrophysics of Life 3: Stellar Evolution The Lives and Deaths of Stars The Lives and Deaths of Stars
Background image of page 1

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

View Full DocumentRight Arrow Icon
On the Main Sequence, the contraction stops because gravity and internal pressure exactly balance each other. Nuclear reactions occur at exactly the right rate to balance gravity. Protostars. These objects radiate energy away in the form of light. That energy comes from gravity – released by contraction. A stars’ mass determines its luminosity
Background image of page 2
Nuclear reactions slowly convert Nuclear reactions slowly convert H to He in the core. H to 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 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-like star Composition of a Sun-like star
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 happens when  the core Hydrogen is  used up? Nuclear reactions stop. Core pressure decreases. Core contracts and gets hotter - heating overlaying layers. 4H 1He burning moves to a hot “shell.”
Background image of page 4
4H 1He reactions occur faster than before. The star gets brighter (more luminous)! The hot shell causes the outer
Background image of page 5

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

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 22

Astrophysics_of_Life_3 - Astrophysics of Life 3: Stellar...

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