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arXiv · 2408.02962

FAST detection of OH emission in the carbon-rich planetary nebula NGC 7027

Xu-Jia Ouyang·Yong Zhang·Chuan-Peng Zhang·Peng Jiang·Jun-ichi Nakashima·Xi Chen·Hai-Hua Qiao·Xu-Ying Zhang·Hao-Min Sun·Xiao-Hu Li·Albert Zijlstra
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Abstract

We present the first detection of the ground-state OH emission line at 1612 MHz toward the prototypical carbon-rich planetary nebula (PN) NGC 7027, utilizing the newly installed ultra-wideband (UWB) receiver of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). This emission is likely to originate from the interface of the neutral shell and the ionized region. The other three ground-state OH lines at 1665, 1667, and 1721 MHz are observed in absorption and have velocities well matched with that of HCO$^+$ absorption. We infer that the OH absorption is from the outer shell of NGC 7027, although the possibility that they are associated with a foreground cloud cannot be completely ruled out. All the OH lines exhibit a single blue-shifted component with respect to the central star. The formation of OH in carbon-rich environments might be via photodissociation-induced chemical processes. Our observations offer significant constraints for chemical simulations, and they underscore the potent capability of the UWB receiver of FAST to search for nascent PNe.

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Xu-Jia Ouyang, Yong Zhang, Chuan-Peng Zhang, Peng Jiang, Jun-ichi Nakashima, Xi Chen, Hai-Hua Qiao, Xu-Ying Zhang, Hao-Min Sun, Xiao-Hu Li, Albert Zijlstra. 2024-08-06. FAST detection of OH emission in the carbon-rich planetary nebula NGC 7027. https://arxiv.org/abs/2408.02962

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