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 2593 HIP 2595 HIP 2598 HIP 2602 HIP 2603 HIP 2632 HIP 2636 HIP 2659 HIP 2663 HIP 2664 HIP 2687 HIP 2688 HIP 2709 HIP 2675 HIP 2711 HIP 2712 HIP 2716 HIP 2717 HIP 2730 HIP 2896 HIP 2984 HIP 2986 HIP 3047 HIP 3096 HIP 3100 HIP 3142 HIP 3147 HIP 3191 HIP 3281 HIP 3331 HIP 3335 HIP 3373 HIP 3374 HIP 3377 HIP 3379 HIP 63828 HIP 63834 HIP 3465 HIP 3466 HIP 63984 HIP 66011 HIP 67509 HIP 67970 HIP 68434 HIP 68438 HIP 68890 HIP 69351 HIP 69811

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