Flamingos spectroscopy of new low-mass members of the young cluster IC 348

We present spectroscopy of candidate stellar and substellar members of the young cluster IC 348. Using the Florida Multi-Object Imaging Near-Infrared Grism Observational Spectrometer with the 4 m telescope at Kitt Peak National Observatory, we have obtained multiobject moderate-resolution (R = 1000) J- and H-band spectra of 66 infrared sources (H = 12-17) toward IC 348, many of which are difficult to observe spectroscopically at optical wavelengths (I > 20) because they are highly reddened and/or intrinsically cool and red. We have also observed 19 known cluster members that have optical spectral types available from previous work. By using these latter sources as the spectral classification standards, we have identified 14 new members of the cluster with types M2-M6 in the sample of 66 new objects. Two additional objects exhibit types later than M8.5 but cannot be conclusively classified as either field dwarfs or cluster members with available data. We have estimated extinctions, luminosities, and effective temperatures for these 16 M-type objects, placed them on the H-R diagram, and used the evolutionary models of Chabrier & Baraffe to estimate their masses. If the two candidates at later than M8.5 are indeed members, they should be among the least massive known brown dwarfs in IC 348 (M/M⊙ ∼0.01).