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We present extensive new spectroscopy and imaging of PNG 135.9+55.9. We use these data as constraints to photoionization models to derive limits on the oxygen abundance. We find that PNG 135.9+55.9 has an oxygen abundance less than 1/50 of the solar value. Our models favour a value of 12 + log O/H between 5.8 and 6.5 dex, confirming that PNG 135.9+55.9 is the most oxygen-poor planetary nebula known (Tovmassian et al. 2001). We also derive Ne/O = 0.5 ± 0.3, S/O < 0.094, and Ar/O < 0.23. Although the value of Ne/O is nominally high, it need not imply that the progenitor of PNG 135.9+55.9 converted any of its initial oxygen abundance to neon. The helium abundance appears to be very low, He/H ~ 0.08, but a precise determination will require a much more detailed study. We find that Hα/Hβ is lower than expected and perhaps variable, a finding for which we have no clear explanation.

Item Type:	Refereed Article
Keywords:	planetary nebulae: individual: PNG 135.9+55.9
Research Division:	Physical Sciences
Research Group:	Astronomical sciences
Research Field:	Stellar astronomy and planetary systems
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the physical sciences
UTAS Author:	Dobbie, PD (Dr Paul Dobbie)
ID Code:	81174
Year Published:	2002
Web of Science® Times Cited:	8
Deposited By:	Mathematics and Physics
Deposited On:	2012-11-26
Last Modified:	2013-06-27
Downloads:	485 View Download Statistics