Overview:
- What is a star?
- Ball of hydrogen
- Balance of fusion and gravity (talk by Connor Stone on elements in the universe)
- Radiation transfer, convection, radiation
- From very small (a tenth of the mass of our sun) to very large (thousand times the mass of our sun)
- What methods are there to destroy a star?
- Wait for it:
- Small stars potentially live for 1Trillion years or more (they burn their fuel much slowly and regulate their temperature much better)
- Sun-like stars tend to puff out after ~10 billion years. Red giant phase, then planetary nebula and white dwarf.
- Nearby white dwarf:
- Having white dwarfs nearby can rip stars apart!
- How close does a star need to be: It actually changes with time. If the two are close enough to each other to trade mass, it means at least part of the main star is in the “Roche limit”
- It is the same process that gives Saturn it's rings.
- It is possible that these don’t always completely destroy the star and so it could happen multiple times.
- Falling into a Black hole:
- It’s not what you would immediately expect. Space is big and by comparison, stars and black holes are small, so the chance of them being in a head-on collision is miniscule. Instead a star will orbit the back hole and slowly get closer, or come in and just miss it, swinging around like a comet almost.
- These are called tidal disruption events. The star comes within the roche limit and is torn apart.
- Black holes are messy eaters, most of the star gets sloppily added to the accretion disk and eventually pushed away from the black hole.
- Supermassive black holes at the centers of galaxies have eaten many stars this way.
Links to Science Outreach Material:
Special thanks to Colin Vendromin for the music, also thanks to Zac Kenny for the logo!