Class G — G-type (Yellow)

G-type stars are yellow main-sequence stars with surface temperatures of 5,200 to 6,000 K. The Sun (G2V) is the most famous G-type star, making this class of particular importance for astrobiology. G-type stars comprise about 7.6% of main-sequence stars. Their spectra are dominated by calcium and iron absorption lines. Other notable G-type stars include Alpha Centauri A (G2V) and Tau Ceti (G8.5V). They have lifetimes of roughly 10 billion years.

G-type stars are yellow stars with surface temperatures between 5,200 and 6,000 K. They comprise about 7.6% of main-sequence stars, and their most famous member is our own Sun (G2V). G-type stars are central to the search for habitable exoplanets because they combine long lifetimes (7-15 billion years on the main sequence) with sufficient luminosity to maintain liquid water at moderate orbital distances — making them prime targets for missions like Kepler, TESS, and the upcoming PLATO.

Characteristics

G-type spectra are characterized by prominent ionized calcium (Ca II) H and K lines, neutral metal lines (especially iron), and the G-band — a molecular absorption feature near 430 nm caused by CH molecules that gives the spectral class its name. G stars have deep convective envelopes that drive magnetic dynamos, producing sunspot cycles, chromospheric activity, coronae, and stellar winds. Their masses range from 0.8 to 1.04 solar masses. G-type giants and supergiants exist at higher luminosities as evolved stars that have left the main sequence.

Notable Examples

The Sun (G2V) is the defining member, the only star whose surface features — granulation, sunspots, prominences — can be studied in exquisite detail. Alpha Centauri A (G2V) is a solar twin and the brightest component of our nearest stellar neighbor at 4.37 light-years. Tau Ceti (G8.5V) is one of the nearest Sun-like stars and has been a target of SETI programs since 1960's Project Ozma. Capella (Alpha Aurigae) is a binary of two G-type giants, the sixth-brightest star system in the sky.

HIP 35073 HIP 84043 HIP 84050 HIP 84055 HIP 84061 HIP 84062 HIP 84063 HIP 84066 HIP 84068 HIP 84069 HIP 51450 HIP 51454 HIP 51455 HIP 51460 HIP 86093 HIP 86096 HIP 86101 HIP 86108 HIP 84075 HIP 84077 HIP 84081 HIP 84089 HIP 84098 HIP 95778 HIP 38131 HIP 8612 HIP 86121 HIP 86127 HIP 8613 HIP 86136 HIP 27643 HIP 2766 HIP 27660 HIP 27666 HIP 2767 HIP 38134 HIP 38139 HIP 38140 HIP 38145 HIP 38146 HIP 84101 HIP 38152 HIP 86140 HIP 86142 HIP 86151 HIP 86154 HIP 84121 HIP 84123

Frequently Asked Questions

What is a class G star?

Class G (G-type (Yellow)) stars are yellow stars. G-type stars are yellow main-sequence stars with surface temperatures of 5,200 to 6,000 K. The Sun (G2V) is the most famous G-type star, making this class of particular importance for astrobiology. G-

How hot are class G stars?

Class G stars have surface temperatures between 5,200 K and 6,000 K.

What color are class G stars?

Class G stars appear yellow.

How many class G stars are in the StarFYI database?

StarFYI currently catalogs 22,793 class G stars.

How luminous are class G stars?

Solar-like, 0.6-1.5 solar luminosities

Class G — G-type (Yellow)

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Characteristics

Notable Examples

Frequently Asked Questions