Term
| low-mass stars are born with how many solar masses? |
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Definition
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Term
| intermediate-mass stars are born with how many solar masses? |
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Definition
| between 2 & 8 solar masses p 533 |
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Term
| high-mass stars are born with how many solar masses? |
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Definition
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Term
| what is the lifetime of our Sun? |
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Definition
| about 10 billion years p 534 |
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Term
| About how long has our Sun been shining? |
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Definition
| about 4.5 billion years p 534 |
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Term
| through what 2 processes does energy move outward from the interior of a low-mass star? |
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Definition
| radiative diffusion and convection p 534 |
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Term
| Convection in the Sun only occurs where, and starts at a depth of what % of the way from the center to the surface? |
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Definition
| occurs only in th router layers, and at a depth of about 70% from the center to the surface p 534 |
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Term
| Stars less massive than the Sun have cooler inheritors, which means what to the depth of their convection zones? |
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Definition
| their convection zones are deeper p 535 |
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Term
| what causes a helium flash in a low-mass star like the Sun? |
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Definition
| the core temp is too low for thermal pressure, so it fights against gravity with degeneracy pressure. because deg. pressure does NOT depend on heat, the fusion heats but does not expand the core. When the temp and helium fusion rate spike, an enormous amount of energy called a helium flash is released into the core p 536 |
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Term
| why does a low-mass star expand after a helium flash? |
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Definition
| the temperature rises so much during a helium flash that eventually the new thermal pressure surpasses degeneracy pressure and pushes back against gravity, causing the core to expand p 536-7 |
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Term
| what happens on the H-R diagram during a helium flash? |
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Definition
| the star spikes upward peaking during the flash, then after it becomes a helium core-fusion star, it drops back down and to the left; how far down an cleft depends on how uch mass it lost during the red giant sage p 537 |
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