the.com/luminosity
the brag a star makes before gravity sends the final invoice
means The quantity or quality of light a thing gives off — in astronomy, the total energy a star or other object radiates into space per second.
from From Latin 'lumen' (light), which gives us 'luminous' and a whole glowing family of words. The noun 'luminosity' arrives through the Latin 'luminositas', built on the same root, and entered English by the 17th century as a learned term for brightness before astronomers borrowed it to measure how fiercely a star burns.
- intrinsic
- true output, not how bright it looks from here
- sun units
- stars measured in multiples of one sun
- hypergiants
- some shine millions of times brighter than ours
- distance trick
- compare true to apparent, and distance falls out
- eddington limit
- shine too hard and you blow yourself apart
sirius — brightest star in night sky, luminosity 26 times greater than sun
betelgeuse — red supergiant, luminosity ~150,000 times the sun's, orion constellation
deneb — blue supergiant, luminosity ~200,000 times the sun's, cygnus constellation