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A Class L star is a type of red dwarf or brown dwarf. They are 65 - 80 times as massive as Jupiter and their temperature is generally in between 1,880 to 3,860°F (1,026.7 to 2,126.7°C) [1]. Massive Class L stars are at the limits of smallest stars capable of fusing hydrogen and helium, whereas less massive ones fuse deuterium and lithium instead[2]. They appear to be a dim orange-red with their spectrum peaking in the infrared.

Class L stars often begin their life with emissions in the Class M spectrum with a temperature of over 4,940 F (2,726.7 C) but cool off and become dimmer over time. The more luminous L-types can live for trillions of years before becoming blue dwarfs. The cores of L-class stars are 3,500,000°K (6,000,000-6,500,000°F)

Class L stars have a habitable zone in between 0.007 and 0.04 AU, or between 1,050,000 to 6,700,000 km, which is 10 - 54 times as close as Mercury's orbit to the Sun. This close distance would leave the planet tidally locked to the star. This combined with the low temperatures, leaves Class L stars extremely poor candidates for life.

While Class L0-L5 types are red dwarfs, the dimmer L6-L9 types are considered brown dwarfs.


The most massive L-class stars will exhaust their hydrogen fuel in about 3-20 trillion years. They will soon collapse under their cores' own gravity, becoming dwarf stars of classes F-B, about the size of Neptune. When the star's collapse is finalized, a white dwarf will be left. The white dwarf will cool down over quadrillions of years before becoming a black dwarf.

For less massive L-class stars, it's a different story. They will just cool and cool, becoming T-class several aeons from now. The Class T star, which was born as Class L, will further cool into a Class Y star. After the Class Y star cools to nearly 2 K, the star will officially be dead, a black dwarf.


Properties of typical L-type main-sequence stars
Spectral type Mass Radius Luminosity Temperature (Fahrenheit)
L0V 0.085 0.110 0.00031 3,680
L1V 0.080 0.105 0.00019 3,320
L2V 0.077 0.100 0.00012 2,996
L3V 0.074 0.097 0.00009 2,780
L4V 0.072 0.092 0.00007 2,690
L5V 0.070 0.088 0.00006 2,600


See Also

Stellar Classes
Φ · Ψ · Ω · Q · DE · GR · σ ς · Θ · N · D · BS · Y · T · L · M · C · S · QS · K · G · F · A · B · LBV · β · O · W · N · X · n0 · Exotic (Π · Σ · Γ · Δ · μ) · δ · I · TŻO · BL · ·
Brown Dwarf Classes
P · Z · Y · T · L