Subaru IR Spectroscopy of Candidate Young Brown Dwarfs and
Planetary-Mass Objects in IC 348
Michael C. Liu, Joan Najita, & Alan Tokunaga
Institute:
Institute for Astronomy, University of Hawaii
Institute: NOAO, Tucson
Contact Email: mliu@ifa.hawaii.edu
Abstract:
We present preliminary results for candidate substellar objects in the
young cluster IC 348 observed with the IRCS spectrograph on the Subaru
8.2-m Telescope. Our sample has been selected from a novel HST NICMOS
narrow-band imaging survey tuned to the 1.9 micron water absorption in
cool stars; the sample is unique in that it is complete down to the
fiducial boundary between brown dwarfs and planets. It contains many
potential free-floating planetary mass objects. We have obtained
K-band spectra of the very coolest candidates in order to measure
their spectral types, and hence obtain mass estimates. Since objects in
young clusters are differentially extincted, we discuss methods of
determining spectral types from reddening independent indices, analogous
to the narrow-band HST imaging originally used to find the candidates.
We demonstrate such techniques can be applied to ground-based spectra
across the entire range of M and L-type atmospheres. Preliminary results
from this work suggest the spectroscopic sample contains both background
stars and cluster members of very low mass.
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Manuscript submitted: 2001-Oct-5
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.