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次毫米波陣列計畫(SMA)

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The HCO+(3–2) line emission at 267 GHz observed with the SMA in the young planetary nebula NGC 7027

圖片來源: Huang, Trung, Hasegawa et al.

The HCO+(3–2) line emission at 267 GHz observed with the SMA in the young planetary nebula NGC 7027 (Huang, Trung, Hasegawa et al. 2006, in preparation). The contours show H2 line emission excited by UV radiation (Cox ets al. 2002, A&A, 384, 603). The col

Circumstellar envelopes around late-type stars can be imaged in both continuum and spectral lines using the SMA. The chemical and excitation variations within these envelopes can be used as probes for studying evolved stars. For example, the photodissociation layer in the circumstellar envelope around the young planetary nebula NGC 7027 was imaged in the HCO+(3-2) emission using the SMA, demonstrating that the HCO+(3-2) emission is closely associated with the H2 line emission observed at near-IR. The HCO+ molecule is likely formed in the region with strong UV radiation through chemical reactions driven by high temperatures (of order 1000 K).