Claim: A-type main-sequence star (dwarf star) Beta Microscopii spins rapidly with a projected rotational velocity of 275 km/s.
Evidence: This is an A-type main-sequence star with a stellar classification of A2 Vn, where 'n' indicates nebulous absorption lines caused by fast rotation. An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V. These stars have spectra which are defined by strong hydrogen Balmer absorption lines. It is spinning rapidly with a projected rotational velocity of 275 km/s.