Fr.: étoile Am
A chemically peculiar A- or early F-type star showing an overabundance of → heavy elements and an underabundance of calcium and scandium. An Am star cannot receive a unique spectral type, as different methods (using the metallic lines, the hydrogen Balmer lines, and the calcium Ca II K-lines) yield three different spectral types. Contrarily to Ap stars, Am stars do not have significant external magnetic fields. Their rotational velocities are about 100-120 km s-1 smaller than those of → Ap stars.
Fr.: étoile à barium
Fr.: étoile d'hélium
An → evolved star which has lost most or all of its hydrogen-rich envelope, leaving just a core of helium.
setâre-ye litiomi (#)
Fr.: étoile à lithium
A peculiar evolved star of spectral type G or M whose spectrum displays a high abundance of lithium.
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.
M, letter of alphabet, → star.
Fr.: étoiles du programme
Stars for the observation of which telescope time has been awarded.