THE SPECTRUM OF THE BROWN DWARF CANDIDATE PC0025+0447

A spectrum of the cool dwarf star PC0025 + 0447 obtained with the Low Resolution Imaging Spectrograph at the Keck telescope yields an upper limit on the lithium to hydrogen ratio. The limit is temperature depen dent and ranges from 5 X 10(-10) for an effective temperature of 2500 K to 1 X 10(-10) at 1900 K. A definitive spectrum of the star's chromo spheric emission is presented, but the prominence of the Balmer series is due to the weak thermal emission of the photosphere, rather than e xtraordinary activity. PC0025+0447 seems more likely to be a cool main sequence star than a young brown dwarf.