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 37151HIP 37154HIP 37158HIP 37164HIP 37165HIP 74902HIP 74905HIP 74907HIP 74930HIP 94034HIP 94049HIP 9405HIP 9209HIP 92097HIP 92100HIP 92101HIP 92102HIP 92103HIP 92108HIP 92110HIP 94057HIP 92157HIP 92169HIP 92172HIP 94120HIP 94121HIP 94125HIP 94126HIP 58285HIP 58287HIP 34089HIP 3409HIP 92220HIP 92224HIP 94184HIP 94190HIP 94194HIP 94195HIP 94196HIP 94271HIP 92324HIP 92325HIP 92326HIP 92332HIP 92340HIP 37250HIP 37252HIP 94458

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