The He I 2.06 micron to Br ratio in 12 planetary nebulae Academic Article uri icon

abstract

  • We present the results of low-resolution (R = 30-100) spectroscopic observations of 12 planetary nebulae between 2.0 and 2.4 m. The data were acquired with a slitless grism imaging system and hence measure emission from each nebula as a whole. The strongest nebular features in this bandpass are found to be He I 2.058 m and Br 2.166 m, which appear in a ratio of He I/Br ranging from less than 0.15 to 1.2. We have compared these measurements with photoionization calculations appropriate for planetary nebulae. The behavior of the He I is dictated in large part by the temperature Teff of the central star and the nebular density ne. Ratios of He I to Br predicted for uniformly expanding nebulae tend to exceed observed values systematically at a given Teff and ne. This behavior can be plausibly accounted for by complex velocity structure within real nebulae.

published proceedings

  • Astrophysical Journal

author list (cited authors)

  • Depoy, D. L., & Shields, J. C.

complete list of authors

  • Depoy, DL||Shields, JC

publication date

  • February 1994