Anomalous intensities in the infrared emission of CH${}^{+}$ explained by quantum nuclear motion and electric dipole calculations

Abstract

The unusual infrared emission patterns of CH${}^{+}$, recently detected in the planetary nebula NGC 7027, are examined theoretically with high-accuracy rovibrational wavefunctions and $ab$ $initio$ dipole moment curves. The calculated transition dipole moments quantitatively reproduce the observed $J$-dependent intensity variation, which is ascribed to underlying centrifugal distortion-induced interference effects. We discuss the implications of this anomalous behavior for astrochemical modeling of CH${}^{+}$ production and excitation, and provide a simple expression to estimate the magnitude of this effect for other light diatomic molecules with small dipole derivatives.

21 pages, 6 figures, accepted for publication in the Astrophysical Journal

References in corpus (5)

• Detection of vibrational emissions from the helium hydride ion (HeH${}^{+}$) in the planetary nebula NGC 7027
• SOFIA/EXES Observations of Water Absorption in the Protostar AFGL 2591 at High Spectral Resolution
• Gas-phase CO2 emission toward Cepheus A East: the result of shock activity?
• Observations and analysis of CH${}^{+}$ vibrational emissions from the young, carbon-rich planetary nebula NGC 7027: a textbook example of chemical pumping
• Very High Excitation Lines of H${}_2$ in the Orion Molecular Cloud Outflow

Cited by in corpus (3)

• PDRs4All III: JWST's NIR spectroscopic view of the Orion Bar
• Self-generated ultraviolet radiation in molecular shock waves II. CH+ and the interpretation of emission from shock ensembles
• PDRs4All XI. Detection of infrared CH${}^{+}$ and CH${}_3^{+}$ rovibrational emission in the Orion Bar and disk d203-506: evidence of chemical pumping