Under the standard spectral color classification, the Sun is a ______.

Concept

Stars are classified by spectral type, which primarily reflects surface temperature. In the simplified color-temperature sequence O-B-A-F-G-K-M, G-type main-sequence stars are described as yellow dwarfs.

Application

The Sun has spectral type G2V and a photospheric temperature of about 5,500 °C. These properties classify it as a G-type, main-sequence yellow dwarf.

Contrast

• A red star belongs to cooler spectral classes, commonly K or M, rather than the G class of the Sun.

• A white main-sequence star is commonly an A-type star. Although sunlight is broadly white outside the atmosphere, that observed-light statement uses a different axis from the simplified spectral class asked here; a white dwarf is a later evolutionary remnant.

• More than one color class would mix distinct temperature classes instead of using one spectral classification axis.

• None of the above would discard the established G-type category.

Cross-check

NASA lists the Sun as a G2V yellow-dwarf main-sequence star, which independently matches the spectral-temperature classification.

Result

Therefore, the Sun is a yellow star.