Class M — M-type (Red)

M-type stars, commonly called red dwarfs, are the coolest and most common main-sequence stars, with surface temperatures of 2,400 to 3,700 K. They make up about 76% of all main-sequence stars, yet none are visible to the naked eye from Earth due to their low luminosity. Proxima Centauri (M5.5Ve), the closest star to the Sun, is an M-type star. Red dwarfs have extremely long lifetimes — trillions of years — far exceeding the current age of the universe. Many host exoplanets, including Proxima Centauri b and the TRAPPIST-1 system.

M-type stars are the coolest, smallest, and by far the most abundant stars in the universe. With surface temperatures below 3,700 K and masses from 0.08 to 0.45 solar masses, red dwarfs constitute approximately 76% of all main-sequence stars — yet not a single one is visible to the naked eye from Earth, despite Proxima Centauri (M5.5Ve) being the nearest star beyond the Sun at just 4.24 light-years. Their extreme longevity (trillions of years) means no M dwarf has ever died of old age in the history of the universe.

Characteristics

M-type spectra are dominated by titanium oxide (TiO) molecular absorption bands, which create their characteristic deep red color. M dwarfs are fully convective below about 0.35 solar masses — meaning they mix their entire hydrogen supply, greatly extending their lifetimes. However, this convection drives powerful magnetic fields that produce frequent, intense flares — some M dwarfs can brighten by factors of 100 in minutes. Their habitable zones lie very close to the star, meaning potentially habitable planets are likely tidally locked. The M class also includes red giants and supergiants — evolved massive stars like Betelgeuse (M1-M2Ia-Iab).

Notable Examples

Proxima Centauri (M5.5Ve) hosts Proxima b, an Earth-mass planet in the habitable zone of our nearest stellar neighbor. TRAPPIST-1 (M8V) has seven Earth-sized planets, three in the habitable zone — the most Earth-like system known. Barnard's Star (M4Ve) is the fastest-moving star in Earth's sky and a target of exoplanet searches since the 1960s. Betelgeuse (Alpha Orionis, M1-M2Ia-Iab) is an M-type red supergiant whose Great Dimming event in 2019-2020 captivated global attention — it will eventually explode as a supernova visible in daylight.

HIP 41749 HIP 41824 HIP 41978 HIP 42013 HIP 42052 HIP 42068 HIP 42070 HIP 42089 HIP 42110 HIP 42117 HIP 42161 HIP 42162 HIP 42176 HIP 42220 HIP 42231 HIP 42239 HIP 42315 HIP 42394 HIP 42411 HIP 42441 HIP 42489 HIP 42502 HIP 42507 HIP 42564 HIP 42601 HIP 42617 HIP 42642 HIP 42656 HIP 42674 HIP 42708 HIP 42700 HIP 42735 HIP 42743 HIP 42744 HIP 42748 HIP 42756 HIP 42762 HIP 42802 HIP 42881 HIP 42921 HIP 43039 HIP 43063 HIP 43207 HIP 43215 HIP 43233 HIP 43245 HIP 43251 HIP 43274

الأسئلة الشائعة

What is a class M star?

Class M (M-type (Red)) stars are red stars. M-type stars, commonly called red dwarfs, are the coolest and most common main-sequence stars, with surface temperatures of 2,400 to 3,700 K. They make up about 76% of all main-sequence stars, yet non

How hot are class M stars?

Class M stars have surface temperatures between 2,400 K and 3,700 K.

What color are class M stars?

Class M stars appear red.

How many class M stars are in the StarFYI database?

StarFYI currently catalogs 5,834 class M stars.

How luminous are class M stars?

Very dim, less than 0.08 solar luminosities