A Novel Survey for Young Substellar Objects with the W-band Filter. VII. Water-Bearing Objects in the Core of the Rho Ophiuchi Cloud Complex

TL;DR

This study identifies and confirms young substellar objects, including brown dwarfs with disks, in the Rho Ophiuchi cloud core using water absorption features, astrometry, and infrared observations.

Contribution

It introduces a water absorption-based selection method for young substellar objects and confirms their membership and properties through multi-faceted analysis.

Findings

21 out of 22 candidates are confirmed members.

15 objects show evidence of circumstellar disks.

Spectroscopy confirms one M8 member and accretion signatures in two sources.

Abstract

We present a study of very low-mass stars and brown dwarfs in the rich star-forming core of the Rho Ophiuchi cloud complex. The selection of the sample relies on detecting the inherent water absorption characteristic in young substellar objects. Of the 22 water-bearing candidates selected, 15 have a spectral type of M6 or later. Brown dwarf candidates too faint for membership determination by Gaia have their proper motions derived by deep-infrared images spanning six years. Astrometric analysis confirms 21/22 sources as members, one identified as a contaminant. Infrared colors and the spectral energy distribution of each water-bearing candidate are used to diagnose the mass, age, and possible existence of circumstellar dust. 15 sources exhibit evidence of disks in their spectral energy distributions, as late as in M8-type objects. Spectroscopy for bright candidates has confirmed one as an M8 member and verified two sources (with disks) exhibiting signatures of magnetospheric accretion.