An Etymological Dictionary of Astronomy and Astrophysics

4 terms — M › M

M MA ME MH MI MJ MK MN MO MÖ MR MU MY

M dwarf   کوتوله‌ی ِ M   kutule-ye M Fr.: naine M A star whose spectrum is dominated by the absorption bands of → titanium oxide (TiO) and → vanadium oxide (VO) and has many neutral metal lines. The → effective temperature of M dwarfs ranges from about 3850 to 2600 K. They are low mass stars with masses ranging from 0.6 times that of the Sun at spectral type M0 to less than 0.1 → solar masses. M dwarfs are very abundant, they account for about 70-80% of stars in the → Galactic disk. The nearest star to the Sun, → Proxima Centauri, is an M dwarf. See also: M, letter of alphabet in the → Harvard classification; → dwarf.

M star   ستاره‌ی ِ M   setâre-ye M (#) Fr.: étoile de type M A cool, red star of spectral type M with a surface temperatures of less than 3600 K. The spectra of M stars are dominated by molecular bands, especially those of TiO. Naked-eye examples are Betelgeuse and Antares. See also: M, letter of alphabet, → star.

M-type asteroid   سیارک ِ گونه‌ی ِ M   sayârak-e gune-ye M Fr.: astéroïde de type M A type of → asteroid that consists of metallic → iron and displays high → albedo (0.10-0.18). M-type asteroids inhabit the middle part of the → asteroid belt. See also: M for → metallic; → type; → asteroid.

M16 M16 Fr.: M16 An → open cluster in the constellation → Serpens associated with the → Eagle Nebula. It is usually mistakenly stated as being that nebula. Also called NGC 6611. First discovered by Philippe Loys de Chéseaux in 1745-6. See also: Object bearing the number 16 in the → Messier catalog.