Hertzsprung-Russell diagram

Assembled from 32 blocks · 2 evidence · 23 related

1. Story
2. A plot of stellar luminosity against surface temperature, devised independently by Ejnar Hertzsprung around 1911 and Henry Norris Russell in 1913, and the instrument that turned stellar evolution from speculation into a readable pattern. Stars do not scatter across it: they fall into a diagonal main sequence, a giant branch, a supergiant region and a faint white dwarf sequence. Because no star visibly changes in a human lifetime, the diagram is the only way to see the stages - a population of stars of different masses and ages is a snapshot of one life history sampled at many points. Hertzsprung was first to distinguish giants from dwarfs; Russell's prestige meant the plot was initially called the Russell diagram, and the name was corrected later. Gaia parallaxes have since replaced schematic versions with an empirical diagram containing over a billion stars. Not a place.
3. Knowledge
4. Main sequence (core hydrogen burning)
5. Hertzsprung-Russell diagram
6. Henry Norris Russell
7. Ejnar Hertzsprung
8. Connections
9. Ejnar Hertzsprung
10. Henry Norris Russell
11. Main sequence (core hydrogen burning)
12. Gaia (ESA astrometric survey)
13. Hertzsprung and Russell independently plot luminosity against temperature
14. Gaia stops observing
15. Gaia Data Release 4 scheduled
16. Hertzsprung-Russell diagram
17. Hertzsprung and Russell independently plot luminosity against temperature
18. Hertzsprung-Russell diagram
19. Payne concludes that stars are mostly hydrogen - and disclaims it
20. Hertzsprung and Russell independently plot luminosity against temperature
21. Payne concludes that stars are mostly hydrogen - and disclaims it
22. Initial stellar mass
23. Protostar
24. Red giant and asymptotic giant branch
25. Hydrogen fusion: the proton-proton chain and the CNO cycle
26. The Sun
27. Hertzsprung-Russell diagram
28. The Sun forms and settles onto the main sequence
29. Hertzsprung and Russell independently plot luminosity against temperature
30. Evidence
31. Supports the description of the main sequence as a mass-ordered band and the 1911/1913 attribution and naming history of the Hertzsprung-Russell diagram. Institutional educational material, read via search summary rather than fetched; not a substitute for the original Hertzsprung and Russell publications.
32. Supports the statement that Gaia parallaxes produced an empirical Hertzsprung-Russell diagram from a very large stellar sample. The paper was not fetched; the source count of nearly two billion refers to the Gaia catalogue as a whole rather than to this paper's sample.