A Novel Survey for Young Substellar Objects with the W-band Filter. I. Filter Design and New Discoveries in Ophiuchus and Perseus

Abstract

We present the design and implementation of a medium-band near-IR filter tailored for detecting low-mass stars and brown dwarfs from the summit of Maunakea. The W-band filter is centered at 1.45 micron with a bandpass width of 6%, designed to measure the depth of the H2O water absorption prominent in objects with spectral types of M6 and later. When combined with standard J- and H-band photometry, the W-band filter is designed to determine spectral types to $\approx$1.4 subtypes for late-M and L dwarfs, largely independent of surface gravity and reddening. This filter's primary application is completing the census of young substellar objects in star-forming regions, using W-band selection to greatly reduce contamination by reddened background stars that impede broad-band imaging surveys. We deployed the filter on the UH 88-inch telescope to survey $\approx$3 sq. deg. of the NGC 1333, IC 348, and rho Ophiuchus star-forming regions. Our spectroscopic followup of W-band selected candidates resulted in the confirmation of 48 ultracool dwarfs with a success rate of 89%, demonstrating the efficacy of this new filter and selection method.

PASP, in press

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Cited by in corpus (11)

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• A novel survey for young substellar objects with the W-band filter VI: Spectroscopic census of sub-stellar members and the IMF of $\sigma$ Orionis cluster
• A wide planetary-mass companion to a young low-mass brown dwarf in Ophiuchus
• The cosmic DANCe of Perseus I: Membership, phase-space structure, mass, and energy distributions
• Disks around young planetary-mass objects: Ultradeep Spitzer imaging of NGC1333
• Search for Brown Dwarfs in IC 1396 with Subaru HSC: Interpreting the Impact of Environmental Factors on Sub-stellar Population
• Spectroscopy of Candidate Members of the Sco-Cen Complex
• Interplay between Young Stars and Molecular Clouds in the Ophiuchus Star-forming Complex
• A Novel Survey for Young Substellar Objects with the W band Filter.V. IC 348 and Barnard 5 in the Perseus Cloud
• An optimised survey strategy for the ERIS/NIX imager: searching for young giant exoplanets and very low mass brown dwarfs using the K-peak custom photometric filter
• Keck Observations in the INfrared of Taurus and $\rho$ Oph Exoplanets And Ultracool dwarfs (KOINTREAU) II: Two Young Bound Companions to Ophiuchus Stars