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 10499 HIP 104993 HIP 104995 HIP 105 HIP 105006 HIP 105012 HIP 105016 HIP 105023 HIP 105025 HIP 105026 HIP 10503 HIP 105032 HIP 105039 HIP 105044 HIP 105049 HIP 105051 HIP 105065 HIP 105071 HIP 105078 HIP 105082 HIP 105083 HIP 105086 HIP 105089 HIP 105095 HIP 1051 HIP 105109 HIP 105111 HIP 105112 HIP 105116 HIP 105117 HIP 105118 HIP 105120 HIP 105126 HIP 105129 HIP 105131 HIP 10516 HIP 105165 HIP 105171 HIP 105174 HIP 105175 HIP 105177 HIP 105183 HIP 105190 HIP 105192 HIP 105198 HIP 1052 HIP 10520 HIP 105202

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