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arXiv · 2509.01122

Unveiling Stellar Feedback and Cloud Structure in the $\rho$ Ophiuchi A Region with ALMA and JWST: Discovery of Substellar Cores, C$^{18}$O Striations, and Protostellar Outflows

Fumitaka Nakamura·Ryohei Kawabe·Shuo Huang·Kazuya Saigo·Naomi Hirano·Shigehisa Takakuwa·Takeshi Kamazaki·Motohide Tamura·James Di Francesco·Rachel Friesen·Kazunari Iwasaki·Chihomi Hara
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Abstract

In clustered star-forming regions, stellar feedback-such as HII regions/photon-dominated regions (PDRs), and protostellar jets/outflows-shapes cloud structures and influences star formation. Using high-resolution ALMA millimeter and JWST infrared data, we analyze the cloud structure and the impact of stellar feedback in the nearest dense cluster-forming region Oph A. All 6 known Class 0/I and 2 of 6 Flat Spectrum/Class II objects are detected in the 1.3 mm dust continuum. Additionally, we newly detected 7 substellar cores, three of which show compact near-infrared emission, suggesting they are young substellar objects. The remaining cores, with masses of 0.01 Msun and high densities, are likely gravitationally bound. They appear connected by faint CO finger-like structures extending from the triple Class 0 system VLA1623-2417 Aa+Ab+B, suggesting they may have been ejected from the close binary VLA1623 Aa+Ab. 12CO and near-infrared data reveal multiple protostellar outflows. From the comparison, we identified several new outflows/jets, and shocked structures associated to the GSS30 large bipolar bubble. Strong 12CO emission traces the eastern edge of the Oph A ridge, forming part of the expanding HII/PDR bubble driven by the nearby Herbig Be star S1. The northern ridge appears blown out, with warm gas flowing toward GSS 30, injecting additional turbulent momentum. Several C18O striations in the S1 bubble align with magnetic fields, and position-velocity diagrams show wave-like patterns, possibly reflecting magnetohydrodynamic waves. Stellar feedback significantly influences Oph A's cloud structure.

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Fumitaka Nakamura, Ryohei Kawabe, Shuo Huang, Kazuya Saigo, Naomi Hirano, Shigehisa Takakuwa, Takeshi Kamazaki, Motohide Tamura, James Di Francesco, Rachel Friesen, Kazunari Iwasaki, Chihomi Hara. 2025-09-01. Unveiling Stellar Feedback and Cloud Structure in the $\rho$ Ophiuchi A Region with ALMA and JWST: Discovery of Substellar Cores, C$^{18}$O Striations, and Protostellar Outflows. https://arxiv.org/abs/2509.01122

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