Monday, November 01, 2021

[wliqgaqa] radiance of a thousand suns

luminosity of main-sequence stars grows by the 3.5 power of mass.  (to do: derive this.)  therefore, a star of 7.2 solar masses shines a thousand times brighter than the sun.  stars of 7.2 solar masses are not that unusual.  unusual stars exceeding 200 solar masses and luminosity 5000000 times that of the sun are nowadays known to exist (but weren't known when the Bhagavad Gita was composed).

previously, on the power range of stars.

or, to experience the sun 1000 times brighter by the inverse square rule, get 31.6 times closer: 6.8 solar radii from the center of the sun, 5.8 radii above the surface.   (Parker solar probe at perihelion: 9.9 solar radii from the center of the sun, sun 480 times brighter.  Mercury: 66 - 100 solar radii.  earth: 211 - 219 solar radii.)

1000-solar-mass stars cannot naturally form nowadays because internally generated stellar wind causes stars and protostars to lose mass or avoid gaining mass beyond a certain point.  the strength of the stellar wind is positively correlated with the metallicity of the star.  (to do: explain more details about this.)  however, metallicity was very low on the early universe, soon after the Big Bang.  therefore, stars of that era, called Population 3, might have reached 1000 solar masses.  they would have been very, very bright.  attempting to observe such stars is at the forefront of astronomy research.  perhaps we should make one.

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