Astrophys. J., 744, 6 (2012/January-1)
Substellar objects in nearby young clusters (SONYC). IV. A census of very low mass objects in NGC 1333.
SCHOLZ A., MUZIC K., GEERS V., BONAVITA M., JAYAWARDHANA R. and TAMURA M.
Abstract (from CDS):
SONYC–Substellar Objects in Nearby Young Clusters–is a program to investigate the frequency and properties of young substellar objects with masses down to a few times that of Jupiter. Here we present a census of very low mass objects in the ∼1 Myr old cluster NGC 1333. We analyze near-infrared spectra taken with Fiber Multi-Object Spectrograph/Subaru for 100 candidates from our deep, wide-field survey and find 10 new likely brown dwarfs with spectral types of M6 or later. Among them, there are three with ≳ M9 and one with early L spectral type, corresponding to masses of 0.006 to ≲ 0.02 M☉, so far the lowest mass objects identified in this cluster. The combination of survey depth, spatial coverage, and extensive spectroscopic follow-up makes NGC 1333 one of the most comprehensively surveyed clusters for substellar objects. In total, there are now 51 objects with spectral type M5 or later and/or effective temperature of 3200 K or cooler identified in NGC 1333; 30-40 of them are likely to be substellar. NGC 1333 harbors about half as many brown dwarfs as stars, which is significantly more than in other well-studied star-forming regions, thus raising the possibility of environmental differences in the formation of substellar objects. The brown dwarfs in NGC 1333 are spatially strongly clustered within a radius of ∼1 pc, mirroring the distribution of the stars. The disk fraction in the substellar regime is <66%, lower than for the total population (83%) but comparable to the brown dwarf disk fraction in other 2-3 Myr old regions.
brown dwarfs - circumstellar matter - planetary systems - stars: formation - stars: low-mass
VizieR on-line data:
<Available at CDS (J/ApJ/744/6): table2.dat table4.dat table6.dat table7.dat tablen1.dat tablen2.dat izcat.dat jkscat.dat> (includes tables 1 and 2 of paper VI = 2012ApJ...756...24S)
Table 2: SONYC NGC 1333-NN (Nos 29-38).
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