We present the results of a search for new circumstellar disks around low-mass stars and brown dwarfs with spectral types > K5 that are confirmed or candidate members of nearby young moving groups .
Our search input sample was drawn from the BANYAN surveys of Malo et al .
and Gagné et al . Two-Micron All-Sky Survey and Wide-field Infrared Survey Explorer data were used to detect near- to mid-infrared excesses that would reveal the presence of circumstellar disks .
A total of 13 targets with convincing excesses were identified : four are new and nine were already known in the literature .
The new candidates are 2MASS J05010082–4337102 ( M4.5 ) , J08561384–1342242 ( M8 \gamma ) , J12474428–3816464 ( M9 \gamma ) and J02265658–5327032 ( L0 \delta ) , and are candidate members of the TW Hya ( \sim 10 \pm 3 Myr ) , Columba ( \sim 42 ^ { +6 } _ { -4 } Myr ) and Tucana-Horologium ( \sim 45 \pm 4 Myr ) associations , with masses of 120 and 13–18 M _ { \mathrm { Jup } } .
The M8–L0 objects in Columba and Tucana-Horologium are potentially among the first substellar disk systems aged \sim 40 Myr .
Estimates of the new candidates ’ mean disk temperatures and fractional luminosities are in the ranges \sim 135 - 520 K and 0.021 - 0.15 , respectively .
New optical spectroscopy of J0501–4337 reveals strong H \alpha emission , possibly indicating ongoing accretion , provides a detection of lithium absorption and a radial velocity measurement that is consistent with a membership to Columba .
We also present a near-infrared spectrum of J0226–5327 that reveals Paschen \beta emission and shows signs of low surface gravity , consistent with accretion from a disk and a young age . Subject headings : Circumstellar matter , Brown dwarfs , Stars : Low-mass , Protoplanetary disks , Infrared : Stars