Chandra Detection of An Evolved Population of Young Stars in Serpens South

Abstract

We present a Chandra study of the deeply embedded Serpens South star-forming region, examining cluster structure and disk properties at the earliest stages. In total, 152 X-ray sources are detected. Combined with Spitzer and 2MASS photometry, 66 X-ray sources are reliably matched to an IR counterpart. We identify 21 class I, 6 flat spectrum, 16 class II, and 18 class III young stars; 5 were unclassified. Eighteen sources were variable in X-rays, 8 exhibiting flare-like emission, and one periodic source. The cluster X-ray luminosity distance was estimated, the best match was to the nearer distance of 260pc for the front of the Aquila Rift complex. The $N_H$ vs. $A_K$ ratio is found to be $\sim$0.68x10${}^{22}$, similar to that measured in other young low mass regions, but lower than that measured in the ISM and high mass clusters ($\sim$1.6-2x10${}^{22}$). We find the spatial distribution closely follows that of the dense filament from which the stars have formed, with the class II population still strongly associated with the filament. There are four sub-clusters in the field, with three forming knots in the filament, and a fourth to the west, which may not be associated but may be contributing to the distributed class III population. A high percentage of diskless class IIIs (upper limit 30% of classified X-ray sources) in such a young cluster could indicate that processing of disks is influenced by the cluster environment and is not solely time-scale dependent.

56 pages, 11 figures, 4 tables

References in corpus (10)

• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• Spitzer Observations of NGC 1333: A Study of Structure and Evolution in a Nearby Embedded Cluster
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• A Spectroscopic Study of Young Stellar Objects in the Serpens Cloud Core and NGC 1333
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Cited by in corpus (10)

• An initial overview of the extent and structure of recent star formation within the Serpens Molecular Cloud using Gaia Data Release 2
• Extension of HOPS Out to 500 ParSecs (eHOPS). I. Identification and Modeling of Protostars in the Aquila Molecular Clouds
• A Census of Star Formation in the Outer Galaxy II: The GLIMPSE360 Field
• 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
• Catalogue of High Protostellar Surface Density Regions in Nearby Embedded Clusters
• Deep Near-Infrared Survey Toward the W40 and Serpens South Region in Aquila Rift: A Comprehensive Catalog of Young Stellar Objects
• The distance to the Serpens South Cluster from H2O masers
• A Novel Survey for Young Substellar Objects with the W-band filter III: Searching for very low mass brown dwarfs in Serpens South and Serpens Core
• Discovery of 22 GHz Water Masers in the Serpens South Region
• Variability and Jet Activity in the YSO MHO~3252~Y3 in Serpens South