A G-type main-sequence star (Spectral type: G-V), often (and imprecisely) called a yellow dwarf, or G dwarf star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.8 to 1.2 solar masses and  surface temperature of between 5,300 and 6,000 K.^{, Tables VII, VIII.} Like other main-sequence stars, a G-type main-sequence star is in the process of converting the element hydrogen to helium in its core by means of nuclear fusion. The Sun, the star to which the Earth is gravitationally bound in the Solar System and the object with the largest Apparent magnitude, is an example of a G-type main-sequence star. Each second, the sun fuses approximately 600 million tons of hydrogen to helium, converting about 4 million tons of matter to energy. Besides the Sun, other well-known examples of G-type main-sequence stars include Alpha Centauri A, Tau Ceti, and 51 Pegasi.