A Lambda Bootis star is a rare type of A star with weak metallic lines (showing a deficiency in heavy elements) and unusually slow rotation. Lambda Bootis stars may be pre-main-sequence objects, or they may be main sequence stars that formed from gas whose metal atoms had been absorbed by interstellar dust. The prototype of the class, Lambda Bootis, lies 97 light-years away in the constellation Boötes. It is of spectral class A0p and has a visual magnitude of 4.18 and a luminosity about 16 times that of the Sun.