Class F — F-type (Yellow-White)

F-type stars are yellow-white stars with surface temperatures of 6,000 to 7,500 K. They make up about 3% of main-sequence stars. Their spectra show weakening hydrogen lines and strengthening calcium and iron lines compared to A-type stars. Notable examples include Canopus (F0II), the second-brightest star, and Procyon (F5IV-V). F-type stars are of great interest in the search for habitable exoplanets because their habitable zones are wider than those of cooler stars. They live for 2-4 billion years.

F-type stars bridge the gap between the hot A-types and the Sun-like G-types, with surface temperatures between 6,000 and 7,500 K. Comprising about 3% of main-sequence stars, they appear yellow-white and are of particular interest to exoplanet researchers because their habitable zones are wider than the Sun's while their lifetimes (2-7 billion years) are potentially long enough for complex life to evolve — though this remains a topic of active debate in astrobiology.

Characteristics

F-type spectra show weakening hydrogen lines and strengthening metal lines, particularly the ionized calcium H and K lines that become increasingly prominent toward later spectral types. F stars mark the transition where convective envelopes first appear, enabling magnetic activity and stellar cycles similar to the Sun's. The late-F stars (F5-F9) show measurable chromospheric activity and starspots. F stars have masses of 1.04-1.4 solar masses and luminosities of 1.5-5 times solar, making them easy targets for radial velocity exoplanet surveys.

Notable Examples

Procyon (Alpha Canis Minoris, F5IV-V) is the eighth-brightest star, a nearby F-type subgiant at 11.5 light-years with a white dwarf companion. Canopus (Alpha Carinae, F0Ib), the second-brightest star in the sky, is actually an F-type supergiant — enormously luminous at 10,700 solar luminosities. Polaris (Alpha Ursae Minoris, F7Ib) is an F-type supergiant and Cepheid variable, famous as the current North Star. The Cepheid period-luminosity relationship, crucial for measuring cosmic distances, was discovered using F and G-type Cepheid variables.

HIP 27594HIP 27595HIP 27596HIP 2760HIP 27601HIP 27604HIP 27605HIP 27633HIP 48585HIP 48591HIP 48592HIP 48593HIP 48596HIP 486HIP 48600HIP 48601HIP 48609HIP 48610HIP 95770HIP 86030HIP 86033HIP 86038HIP 86040HIP 86044HIP 8605HIP 86050HIP 86055HIP 86056HIP 84009HIP 84020HIP 84022HIP 84026HIP 84032HIP 84034HIP 95773HIP 86069HIP 86072HIP 86079HIP 8608HIP 84037HIP 30773HIP 30806HIP 30807HIP 30813HIP 30822HIP 30824HIP 3505HIP 35069

Frequently Asked Questions

What is a class F star?
Class F (F-type (Yellow-White)) stars are yellow-white stars. F-type stars are yellow-white stars with surface temperatures of 6,000 to 7,500 K. They make up about 3% of main-sequence stars. Their spectra show weakening hydrogen lines and strengthening calcium a
How hot are class F stars?
Class F stars have surface temperatures between 6,000 K and 7,500 K.
What color are class F stars?
Class F stars appear yellow-white.
How many class F stars are in the StarFYI database?
StarFYI currently catalogs 25,601 class F stars.
How luminous are class F stars?
Moderate, 1.5-5 solar luminosities