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 25466 HIP 2547 HIP 25482 HIP 25484 HIP 25486 HIP 25494 HIP 25497 HIP 25498 HIP 255 HIP 2550 HIP 25501 HIP 25506 HIP 25509 HIP 25510 HIP 25514 HIP 25516 HIP 25519 HIP 25524 HIP 25526 HIP 25527 HIP 25528 HIP 25531 HIP 25534 HIP 25537 HIP 25545 HIP 25550 HIP 25554 HIP 25564 HIP 25566 HIP 25580 HIP 25590 HIP 25595 HIP 25598 HIP 256 HIP 25604 HIP 25613 HIP 25615 HIP 25629 HIP 25634 HIP 25639 HIP 25641 HIP 25642 HIP 25651 HIP 25652 HIP 25653 HIP 25659 HIP 2566 HIP 25666

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