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A white dwarf, then, packs mass comparable to the Sun's into a volume that is typically a million times smaller than the Sun's; the average density of matter in a white dwarf must therefore be, very roughly, 1 000 000 times greater than the average density of the Sun, or approximately 10 6 g/cm 3, or 1 tonne per cubic centimetre. [1]
When the helium is exhausted, the Sun will repeat the expansion it followed when the hydrogen in the core was exhausted. This time, however, it all happens faster, and the Sun becomes larger and more luminous. This is the asymptotic-giant-branch phase, and the Sun is alternately reacting hydrogen in a shell or helium in a deeper shell.
The Sun is a G-type main-sequence star (G2V) based on spectral class, and it is informally designated as a yellow dwarf because its visible radiation is most intense in the yellow-green portion of the spectrum. It is actually white, but from the Earth's surface, it appears yellow because of atmospheric scattering of blue light. [9]
The Sun is predicted to experience a flash 1.2 billion years after it leaves the main sequence. A much rarer runaway helium fusion process can also occur on the surface of accreting white dwarf stars. Low-mass stars do not produce enough gravitational pressure to initiate normal helium fusion.
The asymptotic-giant-branch phase ends with the ejection of its outer layers as a planetary nebula, leaving the dense core of the Sun behind as a white dwarf. [118] [129] Remnant Sun ~ 1 quadrillion years (10 15 years) ~ 1 quadrillion years in the future Sun cools to 5 K. [143] Gravity of passing stars detaches planets from orbits. Solar System ...
The Sun will exit the main sequence in approximately 5 billion years and start to turn into a red giant. [29] [30] As a red giant, the Sun will grow so large (over 200 times its present-day radius: ~ 215 R ☉; ~ 1 AU) that it will engulf Mercury, Venus, and likely Earth. It will lose 38% of its mass growing, then will die into a white dwarf. [31]
Time in the summer sun can give you more gray hairs by damaging the cells that produce melanin, which gives your hair color. ... Sunlight can also cause hair to turn yellow, a phenomenon called ...
Before it reaches the Chandrasekhar limit (about one and a half times the mass of the Sun, at which point gravitational collapse would start again), the increasing density and temperature within a carbon-oxygen white dwarf initiate a new round of nuclear fusion, which is not regulated because the star's weight is supported by degeneracy rather ...