Bibcode
Rao, N. Kameswara; Lambert, David L.; Reddy, Arumalla B. S.; García-Hernández, D. A.; Manchado, Arturo; Díaz-Luis, J. J.
Bibliographical reference
Publications of the Astronomical Society of the Pacific
Advertised on:
7
2020
Citations
4
Refereed citations
4
Description
We have detected CH+ and CH molecular absorption lines from the youngcompact planetary nebula IC 4997 from high resolution optical spectra. A high-resolution infra-red (H and K bands) spectrum provides detection of H2 emission lines among many other lines. The H2 lines provide an excitation temperature of 2100 K which may result from UV fluorescence in the envelope or from shocks formed at the interface between an expanding outflow of ionized gas and the neutral envelope ejected when the star was on the AGB. It is suggested that the CH+ may result from the endothermic reaction C + H2 → CH+ + H. Intriguingly, CH+ and also CH show a higher expansion velocity than H2 emission suggesting they may be part of the post-shocked gas. * Based on observations obtained with The Nordic Optical Telescope and The Harlan J. Smith Telescope.
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Low- to intermediate-mass (M < 8 solar masses, Ms) stars represent the majority of stars in the Cosmos. They finish their lives on the Asymptotic Giant Branch (AGB) - just before they form planetary nebulae (PNe) - where they experience complex nucleosynthetic and molecular processes. AGB stars are important contributors to the enrichment of the
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