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 66175 HIP 6618 HIP 66183 HIP 66185 HIP 66188 HIP 6619 HIP 66191 HIP 66195 HIP 66197 HIP 66207 HIP 66209 HIP 66210 HIP 66213 HIP 66217 HIP 66224 HIP 66230 HIP 66232 HIP 66233 HIP 66238 HIP 66241 HIP 66243 HIP 66244 HIP 66258 HIP 66261 HIP 66264 HIP 6627 HIP 66273 HIP 66274 HIP 66276 HIP 66287 HIP 66289 HIP 663 HIP 66300 HIP 66312 HIP 66316 HIP 66319 HIP 66325 HIP 66329 HIP 66343 HIP 66344 HIP 66352 HIP 66357 HIP 6636 HIP 66360 HIP 66368 HIP 6637 HIP 66371 HIP 66373

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