Into the Mystic: ALMA ACA observations of the Mystic Mountains in Carina

Reiter, Megan; Klaassen, P D; Moser-Fischer, L; McLeod, A F; Itrich, D

Abstract

We present new observations of the Mystic Mountains cloud complex in the Carina Nebula using the ALMA Atacama Compact Array (ACA) to quantify the impact of strong UV radiation on the structure and kinematics of the gas. Our Band 6 observations target CO, 13CO, and C18O; we also detect DCN J=3–2 and 13CS J=5–4. A dendrogram analysis reveals that the Mystic Mountains are a coherent structure, with continuous emission over −10.5 km s−1 < v < −2 km s−1. We perform multiple analyses to isolate non-thermal motions in the Mystic Mountains including computing the turbulent driving parameter, b, which indicates whether compressive or solenoidal modes dominate. Each analysis yields values similar to other pillars in Carina that have been observed in a similar way but are subject to an order of magnitude less intense ionizing radiation. We find no clear
correlation between the velocity or turbulent structure of the gas and the incident radiation, in contrast to other studies targeting different regions of Carina. This may reflect differences in the initial densities of regions that go on to collapse into pillars and those that still look like clouds or walls in the present day. Pre-existing over-densities that enable pillar formation may also explain why star formation in the pillars appears more evolved (from the presence of jets) than in other heavily irradiated but non-pillar-like regions. High resolution observations of regions subject to an array of incident radiation are required to test this hypothesis.

Citation

Reiter, M., Klaassen, P. D., Moser-Fischer, L., McLeod, A. F., & Itrich, D. (2023). Into the Mystic: ALMA ACA observations of the Mystic Mountains in Carina. Monthly Notices of the Royal Astronomical Society, 526(1), 717–739. https://doi.org/10.1093/mnras/stad2750

• Journal Article Type: Article
• Acceptance Date: Aug 27, 2023
• Online Publication Date: Sep 23, 2023
• Publication Date: 2023-11
• Deposit Date: Jan 30, 2024
• Publicly Available Date: Jan 30, 2024
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 526
• Issue: 1
• Pages: 717–739
• DOI: https://doi.org/10.1093/mnras/stad2750
• Public URL: https://durham-repository.worktribe.com/output/2187850