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 67335HIP 67351HIP 67357HIP 67362HIP 67365HIP 67431HIP 67432HIP 67437HIP 67438HIP 67440HIP 67441HIP 67442HIP 67443HIP 67444HIP 67446HIP 67450HIP 67451HIP 67452HIP 67430HIP 88022HIP 67547HIP 32755HIP 32760HIP 32765HIP 32775HIP 32778HIP 96748HIP 9676HIP 88105HIP 8816HIP 88161HIP 88392HIP 88393HIP 88399HIP 67856HIP 32819HIP 98644HIP 90372HIP 90387HIP 90388HIP 90390HIP 90391HIP 67914HIP 67915HIP 90403HIP 88453HIP 88455HIP 88457

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