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Below there are lists the nearest stars separated by spectral type.The scope of the list is still restricted to the main sequence spectral types: M, K, F, G, A, B and O.It may be later expanded to other types, such as S, D or C.
One possibility is that these stars were much larger than current stars: several hundred solar masses, and possibly up to 1,000 solar masses. Such stars would be very short-lived and last only 2–5 million years. [32] Such large stars may have been possible due to the lack of heavy elements and a much warmer interstellar medium from the Big Bang.
These are the rarest of all main-sequence stars. About 1 in 3,000,000 (0.00003%) of the main-sequence stars in the solar neighborhood are O-type stars. [c] [11] Some of the most massive stars lie within this spectral class. O-type stars frequently have complicated surroundings that make measurement of their spectra difficult.
From parallax measurements, the distance to this star is about 160 ± 10 ly (49.1 ± 3.1 pc). It has an apparent visual magnitude of 2.89, [ 4 ] making it easily visible to the naked eye. Beta Canis Minoris has about 3.5 times the Sun's mass and is rotating rapidly with a projected rotational velocity of 210 km s −1 , [ 9 ] which gives a ...
O class stars are short-lived, and will expire as supernovae after roughly one to fifteen million years, depending on the mass of the star. As a result, OB associations are generally only a few million years in age or less. The O-B stars in the association will have burned all their fuel within 10 million years.
On the other hand, the Big Bang produced lithium-6 at levels more than 1000 times smaller. 7 4 Be later decayed via electron capture (half-life 53.22 days) into 7 3 Li, so that the observable primordial lithium abundance essentially sums primordial 7 3 Li and radiogenic lithium from the decay of 7 4 Be. These isotopes are produced by the reactions
As of 2017, there are over 52,011 known variable stars, [1] with more being discovered regularly, so a complete list of every single variable is impossible at this place (cf. GCVS). The following is a list of variable stars that are well-known, bright, significant, or otherwise interesting.
The Indestructibles (Ancient Egyptian: j.ḫmw-sk – literally "the ones not knowing destruction" [1] [2]) was the name given by ancient Egyptian astronomers to two bright stars which, at that time, could always be seen circling the North Pole. [3]