The role of low-mass star clusters in forming the massive stars in DR 21

Abstract

We have studied the young low-mass pre-main sequence (PMS) stellar population associated with the massive star-forming region DR 21 by using archival X-ray Chandra observations and by complementing them with existing optical and IR surveys. The Chandra observations have revealed for the first time a new highly extincted population of PMS low-mass stars previously missed in observations at other wavelengths. The X-ray population exhibits three main stellar density peaks, coincident with the massive star-forming regions, being the DR 21 core the main peak. The cross-correlated X-ray/IR sample exhibits a radial "Spokes-like" stellar filamentary structure that extends from the DR 21 core towards the northeast. The near IR data reveal a centrally peaked structure for the extinction, which exhibits its maximum in the DR 21 core and gradually decreases with the distance to the N-S cloud axis and to the cluster center. We find evidence of a global mass segregation in the full low-mass stellar cluster, and of an stellar age segregation, with the youngest stars still embedded in the N-S cloud, and more evolved stars more spatially distributed. The results are consistent with the scenario where an elongated overall potential well created by the full low-mass stellar cluster funnels gas through filaments feeding stellar formation. Besides the full gravitational well, smaller-scale local potential wells created by dense stellar sub-clusters of low-mass stars are privileged in the competition for the gas of the common reservoir, allowing the formation of massive stars. We also discuss the possibility that a stellar collision in the very dense stellar cluster revealed by Chandra in the DR 21 core is the origin of the large-scale and highly-energetic outflow arising from this region.

16 pages, 17 figures, 2 tables. Accepted for publication in MNRAS

References in corpus (11)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• Star formation through gravitational collapse and competitive accretion
• Using the minimum spanning tree to trace mass segregation
• WFCAM, Spitzer-IRAC and SCUBA observations of the massive star forming region DR21/W75: I. The collimated molecular jets
• Monitoring the Large Proper Motions of Radio Sources in the Orion BN/KL Region
• Outflows from Massive YSOs as Seen with the Infrared Array Camera
• X-ray properties of protostars in the Orion Nebula
• WFCAM, Spitzer-IRAC and SCUBA observations of the massive star forming region DR21/W75: II. Stellar content and star formation
• A 10,000 Years Old Explosion in DR21
• The Progression of Star Formation in the Rosette Molecular Cloud
• The role of low-mass star clusters in massive star formation. The Orion Case

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