4) why is there is a lower-limit to the mass of main sequence stars
Main sequence The observed upper limit for a main-sequence star is 120–200 M☉.[36] The theoretical explanation for this limit is that stars above this mass can not radiate energy fast enough to remain stable, so any additional mass will be ejected in a series of pulsations until the star reaches a stable limit.[37] The lower limit for sustained proton–proton nuclear fusion is about 0.08 M☉ or 80 times the mass of Jupiter.[33] Below this threshold are sub-stellar objects that can not sustain hydrogen fusion, known as brown dwarfs.[38]
Masoretic Text The Masoretic[1] Text (MT or
Main sequence In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage.[3] More massive stars can explode as a supernova,[4] or collapse directly into a black hole.
Hundreds and thousands Hundreds and thousands used incorrectly instead of hundreds of thousands to mean "an indefinite but emphatically large number".
Corona Spectroscopy measurements indicate strong ionization and plasma temperature in excess of 1,000,000 kelvins,[1] much hotter than the surface of the Sun.
Diagonalizable matrix Note that the above examples show that the sum of diagonalizable matrices need not be diagonalizable.