Astrophysics (index)about

M-type star

(M)
(spectral type of star with a temperature in the vicinity of 2500K)

An M-type star is of the M-class, a spectral class for cool stars including red dwarves (M-dwarf main sequence stars), red giants (which are beyond their main sequence), and some hotter brown dwarfs. The common element is the temperature, which is less than (other) main sequence stars. They have very weak hydrogen absorption lines.

Some red dwarfs are Proxima Centauri, Barnard's Star, Lacaille 9352, Lalande 21185, Ross 154, Ross 248, Wolf 359, and Gliese 581.

Some characteristics of main-sequence M dwarfs:

redconventional color
2000-3700Ksurface temperature
.96-1.15radius(solar)
<.45mass(solar)
8-20absolute magnitude(visual)
0.08-0.6bolometric luminosity(solar)
1-10 trillion yearsmain-sequence lifetime
76.45%abundance

Subclasses, with mass, radius and luminosity of main-sequence M dwarfs as a fraction of the solar values:

classmassradiusluminositytemp(K)
M0.6.62.0723800"Early"
M1.49.49.0353600
M2.44.44.0233400
M3.36.39.0153250
M4.20.26.00553100
M5.14.20.00222800"Mid"
M6.10.15.00092600
M7.09.12.00052500
M8.08.11.00032400
M9.075.08.000152300"Late"

A Roman numeral V suffix (e.g., M7V) indicates specifically a main sequence (dwarf, as in non-giant) star.

An example M-class red giant is Betelgeuse. The red giant phase lasts on the order of a billion years. Their size gives them their brighter absolute magnitude despite their low temperature.


(star type,spectral type)
http://en.wikipedia.org/wiki/Stellar_classification

Referenced by:
AU Microscopii (AU Mic)
Bcool
brown dwarf (BD)
calcium (Ca)
K2
K-type star (K)
L-type star (L)
M dwarf
solar mass (MSun)
Orion
planet demographics
red dwarf
red giant
red-giant branch (RGB)
Scholz's Star
spectral class
Spectroscopic Properties of Cool Stars (SPOCS)
star formation (SF)
stellar demographics
Transiting Exoplanet Survey Satellite (TESS)
TW Hydrae association (TWA)
ultracool dwarf
Wilson-Bappu effect

index