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 19480HIP 19484HIP 19486HIP 1949HIP 22916HIP 22918HIP 22919HIP 22920HIP 22924HIP 22934HIP 22938HIP 19496HIP 19501HIP 19504HIP 19507HIP 19514HIP 19516HIP 19521HIP 19524HIP 22947HIP 22949HIP 2295HIP 22956HIP 22963HIP 22967HIP 22970HIP 19527HIP 19528HIP 1953HIP 19530HIP 19535HIP 19543HIP 19546HIP 19549HIP 19553HIP 22976HIP 22977HIP 22981HIP 22986HIP 2299HIP 230HIP 19556HIP 19564HIP 1957HIP 19575HIP 19579HIP 1958HIP 19580

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