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arXiv · 2002.02473

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·Loıc Albert·Sophie Dubber·Katelyn Allers·Gregory J. Herczeg·Michael C. Liu·Samuel Pearson·Bhavana Lalchand·Wen-Ping Chen·Mickael Bonnefoy·Etienne Artigau·Philippe Delorme·Po-shih Chiang·Zhoujian Zhang·Yumiko Oasa
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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 sub-stellar objects, yet the low-mass members of this region remain largely undiscovered. In this paper we report on a deep photometric survey using a custom 1.45 um 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 um 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 4 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 Pa_beta and Br_gamma 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.

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Jessy Jose, Beth A. Biller, Loıc Albert, Sophie Dubber, Katelyn Allers, Gregory J. Herczeg, Michael C. Liu, Samuel Pearson, Bhavana Lalchand, Wen-Ping Chen, Mickael Bonnefoy, Etienne Artigau, Philippe Delorme, Po-shih Chiang, Zhoujian Zhang, Yumiko Oasa. 2020-04-03. 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. https://doi.org/10.3847/1538-4357%2Fab74dd

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