IFU spectroscopy of southern PN VI: The extraordinary chemo-dynamics of Hen 2-111

M. A. Dopita, A. Ali, A. I. Karakas, D. Goldman, M. A. Amer, R. S. Sutherland

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Abstract

In this paper, we present integral field spectroscopy of the extraordinary Type I bipolar planetary nebula Hen 2-111. In the lobes, we map fast-moving knots of material with [N II] λ6584/Hα ratios up to 12, and with radial velocities relative to systemic from -340 up to +390 km s -1 . We find evidence of a bipolar ejection event at a velocity ~600 km s -1 from the central star (assumed to be a binary), which occurred about 8000 yr ago. The fastmoving material is chemically quite distinct from the lower velocity gas in the bipolar lobes, and displays very high N abundances. We show that the fast-moving N-rich knots are not photoionized by the central star, and have constructed detailed shock models for the brightest knot. We find a pre-shock density ~6 cm -3 , and a shock velocity ~150 km s -1 . The shock is not fully radiative, being only ~600 yr old. This shocked gas is partially H-burnt, with helium abundance by mass exceeding that of hydrogen, and is interacting with partially H-burnt material ejected in an earlier episode of mass loss.We conclude that the high-velocity material and the bipolar shell must have originated during the late stages of evolution of a common-envelope phase in a close binary system.

Original languageEnglish
Pages (from-to)424-437
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume475
Issue number1
DOIs
Publication statusPublished - 21 Mar 2018

Keywords

  • ISM: abundances
  • ISM: jets and outflows
  • Planetary nebulae: individual: Hen 2-111
  • Shock waves
  • Stars: AGB and post-AGB
  • Stars: mass-loss

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