Changes in the Planetary Nebula IC 4997
Open Access
- 1 April 1966
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 132 (2) , 337-345
- https://doi.org/10.1093/mnras/132.2.337
Abstract
Spectrophotometric measurements of the spectrum of the planetary nebula IC 4997 show that the λ 4363 line of [O III] is currently decreasing in intensity relative to the λ 4959, λ 5007 forbidden lines of the same ion. The authors give evidence to support the idea that the spectral changes result from an expansion of the nebula with a corresponding decrease both in electron density and electron temperature.Keywords
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