Mdwarf

Mdwarf, short for M-dwarf, refers to a class of small, cool stars of spectral type M that are on the main sequence. They are the most common type of star in the Milky Way, making up a large fraction of the stellar population in the Galactic disk. Mdwarfs form like other low-mass stars from the gravitational collapse of molecular clouds and burn hydrogen steadily over very long timescales.

Physically, Mdwarfs have masses about 0.08 to 0.6 solar masses, radii roughly 0.1 to 0.6 solar radii, and surface temperatures between about 2,400 and 3,700 Kelvin. Their luminosities are low, typically less than a few percent of the Sun’s, which makes them faint in visible light but relatively bright in the near infrared. Stars with masses below about 0.35 solar masses are fully convective, affecting their internal mixing and evolution.

Mdwarfs exhibit strong magnetic activity at many ages, including starspots, flares, and emission in hydrogen lines. This activity is linked to rapid rotation and winds, and may influence the atmospheres of orbiting planets. The habitable zones around Mdwarfs lie close to the star, so planets in these zones are often tidally locked, with implications for climate and potential habitability.

In exoplanet research, Mdwarfs are prominent targets because their small size makes transits deeper and radial-velocity signals easier to detect. Notable nearby Mdwarfs include Proxima Centauri and the TRAPPIST-1 system. The long lifetimes of Mdwarfs mean their planets could persist for very long periods.