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 3723 HIP 37233 HIP 37234 HIP 37247 HIP 37249 HIP 37255 HIP 37258 HIP 3726 HIP 3728 HIP 37291 HIP 37292 HIP 37299 HIP 37301 HIP 37305 HIP 37309 HIP 37314 HIP 37316 HIP 37319 HIP 37327 HIP 37332 HIP 37335 HIP 37337 HIP 37338 HIP 37353 HIP 37360 HIP 37378 HIP 3738 HIP 37384 HIP 37387 HIP 37393 HIP 37398 HIP 37403 HIP 37419 HIP 37427 HIP 37435 HIP 37445 HIP 3745 HIP 37484 HIP 37486 HIP 37489 HIP 37503 HIP 37510 HIP 37520 HIP 37525 HIP 37538 HIP 3754 HIP 37542 HIP 3755

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