A Novel Survey for Young Substellar Objects with the W-band Filter. II. The Coolest and Lowest Mass Members of the Serpens-South Star-forming Region

Jessy Jose*, Beth A. Biller, Loïc Albert, Sophie Dubber, Katelyn Allers, Gregory J. Herczeg, Michael C. Liu, Samuel Pearson, Bhavana Lalchand, Wen Ping Chen, Mickaël Bonnefoy, Etienne Artigau, Philippe Delorme, Po Shih Chiang, Zhoujian Zhang, Yumiko Oasa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Given its relative proximity (∼430 pc), compact size (<20′), young age (∼0.5 Myr), and rich number of young stellar objects, the Serpens-South star-forming region is a promising site for studying young substellar objects, yet the low-mass members of this region remain largely undiscovered. In this article we report on a deep photometric survey using a custom 1.45 μm filter (W band), as well as standard J and H near-IR filters, in order to identify candidate low-mass young brown dwarfs in the Serpens-South region. We constructed a reddening-insensitive index (Q) by combining J, H and W-band photometry for survey objects, in order to identify candidate low-mass members of Serpens based on the strength of the water-absorption feature at 1.45 μm in the atmospheres of mid-M and later objects. We then conducted spectroscopic follow-up to confirm youth and spectral type for our candidates. This is the first survey to identify the very low-mass and coolest members of Serpens-South. We identify four low-mass candidate Serpens members, which all display IR excess emission, indicating the likely presence of circumstellar disks around them. One of the four candidate low-mass members in our list, SERP182918-020245, exhibits Paβ and Brγ emission features, confirming its youth and ongoing magnetospheric accretion. Our new candidate members have spectral types >M4 and are the coolest and lowest mass candidate members yet identified in Serpens-South.

Original languageEnglish
Article number122
JournalAstrophysical Journal
Volume892
Issue number2
DOIs
Publication statusPublished - 3 Apr 2020

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