Planetary nebula

Assembled from 23 blocks · 1 evidence · 28 related

1. Story
2. The ejected envelope of a dying intermediate-mass star, lit up by the exposed stellar core it surrounds. The name is a historical accident - eighteenth-century observers thought the discs resembled planets - and the objects have nothing to do with planets. The phase is brief: the exposed core must heat past roughly 30,000 K and begin ionising the ejected gas before that gas disperses, and the resulting nebula is visible for something on the order of ten thousand to twenty-five thousand years before fading into the interstellar medium. That is the mechanism by which carbon, nitrogen and other products of intermediate-mass stellar burning are returned to the gas from which the next generation of stars forms. What remains at the centre is a white dwarf. Not a place on Earth.
3. Knowledge
4. Giant molecular cloud
5. Red giant and asymptotic giant branch
6. Planetary nebula
7. Connections
8. Red giant and asymptotic giant branch
9. Giant molecular cloud
10. Main sequence (core hydrogen burning)
11. Betelgeuse (Alpha Orionis)
12. Planetary nebula
13. White dwarf
14. Betelgeuse fades by more than a magnitude
15. Eagle Nebula (Messier 16) and the Pillars of Creation
16. Protostar
17. Planetary nebula
18. Supernova
19. The first stars form from metal-free gas
20. The Sun forms and settles onto the main sequence
21. Hubble photographs the Pillars of Creation
22. Evidence
23. Supports the description of the planetary nebula phase as brief, on the order of ten thousand to twenty-five thousand years, following AGB mass loss of roughly 40 to 80 per cent of the star. The page was not fetched; figures come from a search summary and vary between sources.