A survey for planetary-mass brown dwarfs in the Chamaeleon I star-forming region

Abstract

We have performed a search for planetary-mass brown dwarfs in the Chamaeleon I star-forming region using proper motions and photometry measured from optical and infrared images from the Spitzer Space Telescope, the Hubble Space Telescope, and ground-based facilities. Through near-infrared spectroscopy at Gemini Observatory, we have confirmed six of the candidates as new late-type members of Chamaeleon I >M7.75. One of these objects, Cha J11110675-7636030, has the faintest extinction-corrected M_K among known members, which corresponds to a mass of 3-6 M_Jup according to evolutionary models. That object and two other new members have redder mid-IR colors than young photospheres at <M9.5, which may indicate the presence of disks. However, since those objects may be later than M9.5 and the mid-IR colors of young photospheres are ill-defined at those types, we cannot determine conclusively whether color excesses from disks are present. If Cha J11110675-7636030 does have a disk, it would be a contender for the least-massive known brown dwarf with a disk. Since the new brown dwarfs that we have found extend below our completeness limit of 6-10 M_Jup, deeper observations are needed to measure the minimum mass of the initial mass function in Chamaeleon I.

Accepted for publication in The Astronomical Journal; 8 pages, 12 figures, 1 machine readable tables avaiable at at https://www.dropbox.com/s/e5oms3bb9ing4ap/tab1_2017.txt?dl=0

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• The Gaia mission
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• The Stellar Population of the Chamaeleon I Star-Forming Region
• The Disk Population of the Chamaeleon I Star-Forming Region
• Discovery of a Young Substellar Companion in Chamaeleon
• The Gaia-ESO Survey: Chromospheric Emission, Accretion Properties, and Rotation in $\gamma$ Velorum and Chamaeleon I
• Direct evidence of a sub-stellar companion around CT Cha
• A Survey for New Members of the Taurus Star-Forming Region with the Sloan Digital Sky Survey
• New Low-Mass Stars and Brown Dwarfs with Disks in the Chamaeleon I Star-Forming Region
• Spectroscopy of brown dwarf candidates in IC 348 and the determination of its substellar IMF down to planetary masses
• A Search for Companions to Brown Dwarfs in the Taurus and Chamaeleon Star Forming Regions

Cited by in corpus (16)

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• The protoplanetary disk population in the rho-Ophiuchi region L1688 and the time evolution of Class II YSOs
• A Census of the Stellar Populations in the Sco-Cen Complex
• A Survey For Planetary-mass Brown Dwarfs in the Taurus and Perseus Star-forming Regions
• Chamaeleon DANCe. Revisiting the stellar populations of Chamaeleon I and Chamaeleon II with Gaia-DR2 data
• A Survey for New Stars and Brown Dwarfs in the Ophiuchus Star-forming Complex
• A Census of Stars and Disks in Corona Australis
• A Census of the Low Accretors. I: The Catalog
• New low-mass members of Chamaeleon I and $\epsilon$ Cha
• Disks around young planetary-mass objects: Ultradeep Spitzer imaging of NGC1333
• Spectroscopic substellar initial mass function of NGC 2244
• New Candidates for Planetary-mass Brown Dwarfs in IC 348
• Discovery of two nearby post-T Tauri stellar associations
• A Random Forest Approach to Identifying Young Stellar Object Candidates in the Lupus Star-Forming Region
• Fast Photometric Variability of Very Low Mass Stars in IC 348: Detection of Superflare in an M-dwarf