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A G-type main-sequence star (spectral type: G-V), also often, and imprecisely, called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temperature between about 5,300 and 6,000 K (5,000 and 5,700 °C ; 9,100 and 10,000 °F ).
The Sun is a G-type main-sequence star (G2V), informally called a yellow dwarf, though its light is actually white. It formed approximately 4.6 billion [a] years ago from the gravitational collapse of matter within a region of a large molecular cloud.
The habitable zone around yellow dwarfs varies according to their size and luminosity, although the inner boundary is usually at 0.84 AU and the outer one at 1.67 in a G2V class dwarf like the Sun. [19] In a G5V class dwarf -smaller- of 0.95 R☉ the habitable zone would correspond to the region located between 0.8 and 1.58 AU with respect to ...
On November 4, 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarf stars within the Milky Way galaxy. [7] [8] Eleven billion of these estimated planets may be orbiting Sun-like stars. [9]
Several other planets, such as Gliese 180 b, also appear to be examples of planets once considered potentially habitable but later found to be interior to the habitable zone. [ 1 ] Similarly, Tau Ceti e and f were initially both considered potentially habitable, [ 67 ] but with improved models of the circumstellar habitable zone, as of 2022 PHL ...
Artist's impression of tundra on an inhabited planet around a spectral class F5 star. The habitability of F-type main-sequence star (or yellow-white dwarf) systems is disputed due to the shorter lifetimes (3–8 Gyrs as opposed to 9–15 Gyrs for G stars) and higher levels of UV radiation.
The closest encounter to the Sun so far predicted is the low-mass orange dwarf star Gliese 710 / HIP 89825 with roughly 60% the mass of the Sun. [4] It is currently predicted to pass 0.1696 ± 0.0065 ly (10 635 ± 500 au) from the Sun in 1.290 ± 0.04 million years from the present, close enough to significantly disturb the Solar System's Oort ...
Kappa 1 Ceti is a yellow dwarf star of the spectral type G5Vv. [3] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. [14] The star has roughly the same mass as the Sun, with 95% of the Sun's radius [8] but only 85 percent of the luminosity. [9]