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 25150 HIP 25154 HIP 70023 HIP 28441 HIP 28443 HIP 2845 HIP 70024 HIP 70025 HIP 70032 HIP 70038 HIP 25166 HIP 25181 HIP 83246 HIP 28460 HIP 28474 HIP 25190 HIP 25191 HIP 28485 HIP 28497 HIP 28502 HIP 28503 HIP 25219 HIP 25238 HIP 70043 HIP 7005 HIP 70053 HIP 70054 HIP 70058 HIP 70068 HIP 25257 HIP 25270 HIP 25272 HIP 28548 HIP 2855 HIP 28550 HIP 28554 HIP 25275 HIP 25277 HIP 25289 HIP 2882 HIP 28824 HIP 34667 HIP 34671 HIP 26022 HIP 26028 HIP 26037 HIP 26040 HIP 67716

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