New Maser Emission from Nonmetastable Ammonia in NGC 7538. III. Detection of the (10,6) Transition and a Velocity Gradient

Abstract

We present the first astronomical detection of the 14NH3 (J,K) = (10,6) line: nonthermal emission at several velocities in the Galactic star-forming region NGC 7538. Using the VLA we have imaged the (10,6) and (9,6) ammonia masers at several positions within NGC 7538 IRS 1. The individual sources have angular sizes < 0.1 arcseconds corresponding to brightness temperatures T_B > 1E6 K. We apply the pumping model of Brown & Cragg, confirming the conjecture that multiple ortho-ammonia masers can occur with the same value of K. The positions and velocities of the (10,6) and (9,6) masers are modeled as motion in a possible disk or torus and are discussed in the context of recent models of the region.

6 pages, 5 figures, 1 table; emulateapj, accepted to ApJ; color figures only on arXiv

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• KFPA Examinations of Young STellar Object Natal Environments (KEYSTONE): Hierarchical Ammonia Structures in Galactic Giant Molecular Clouds
• New Maser Emission from Nonmetastable Ammonia in NGC 7538. IV. Coincident Masers in Adjacent States of Para-ammonia
• Ammonia masers toward G358.931-0.030
• Discovery of widespread non-metastable ammonia masers in the Milky Way
• Broadband VLA Spectral Line Survey of a Sample of Ionized Jet Candidates