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 96185 HIP 96188 HIP 96191 HIP 962 HIP 96200 HIP 96213 HIP 96224 HIP 96232 HIP 96239 HIP 96250 HIP 96259 HIP 96262 HIP 96265 HIP 96273 HIP 96280 HIP 96289 HIP 9629 HIP 96296 HIP 963 HIP 9630 HIP 96308 HIP 96312 HIP 96331 HIP 96332 HIP 96333 HIP 96334 HIP 96344 HIP 96345 HIP 96349 HIP 9635 HIP 96352 HIP 96361 HIP 96368 HIP 96369 HIP 9637 HIP 96370 HIP 96374 HIP 96375 HIP 96378 HIP 96379 HIP 96380 HIP 96389 HIP 96395 HIP 96396 HIP 96402 HIP 9641 HIP 96412 HIP 9642

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