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 8149 HIP 81494 HIP 815 HIP 8150 HIP 81503 HIP 81509 HIP 81510 HIP 81513 HIP 81524 HIP 81525 HIP 81532 HIP 81535 HIP 8155 HIP 81553 HIP 81559 HIP 8156 HIP 81561 HIP 81571 HIP 81572 HIP 81575 HIP 8158 HIP 81580 HIP 81606 HIP 81608 HIP 81610 HIP 81612 HIP 81614 HIP 81617 HIP 81619 HIP 81631 HIP 81657 HIP 81658 HIP 81662 HIP 8167 HIP 81671 HIP 81675 HIP 81677 HIP 81682 HIP 81684 HIP 81686 HIP 8169 HIP 81698 HIP 81704 HIP 81706 HIP 81708 HIP 81713 HIP 81714 HIP 81715

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