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Temperature Variations from HST Imagery and Spectroscopy of NGC 7009

Published online by Cambridge University Press:  26 May 2016

R. H. Rubin ,
N. J. Bhatt ,
R. J. Dufour ,
B. A. Buckalew ,
M. J. Barlow ,
X.-W. Liu ,
P. J. Storey ,
B. Balick ,
G. J. Ferland  and
J. P. Harrington
...Show all authors
R. H. Rubin
Affiliation:
2 NASA/Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA 3 Orion Enterprises, ([email protected])
N. J. Bhatt
Affiliation:
2 NASA/Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA
R. J. Dufour
Affiliation:
4 Rice University
B. A. Buckalew
Affiliation:
4 Rice University
M. J. Barlow
Affiliation:
5 University College London
X.-W. Liu
Affiliation:
5 University College London
P. J. Storey
Affiliation:
5 University College London
B. Balick
Affiliation:
6 University of Washington
G. J. Ferland
Affiliation:
7 University of Kentucky
J. P. Harrington
Affiliation:
8 University of Maryland
P. G. Martin
Affiliation:
9 CITA, University of Toronto

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We obtained new HST/STIS long-slit spectra and WFPC2 imagery of the planetary nebula NGC 7009 in order to obtain high spatial resolution of the intrinsic flux ratio [O III] 4364/5008, which is a well-known diagnostic for electron temperature (Te). Our primary purpose was to quantify Te variations across the nebula. We address whether the observational data support the possibility that the [fractional] mean-square Te variation (t2) (Peimbert 1967) in NGC 7009 may be as large as ~0.1. Such large values are required to reconcile the “abundance dichotomy” by Te variations alone. The abundance dichotomy (discussed by Liu at greater length elsewhere in this volume) refers to the significantly higher heavy element abundances derived from optical recombination lines (e.g., a factor of ~5 for NGC 7009, Liu et al. 1995) compared with the corresponding values deduced from collisionally-excited lines.

Type
Part VI: The Ionized Gas in Planetary Nebulae
Information
Symposium - International Astronomical Union , Volume 209: Planetary Nebulae: Their Evolution and Role in the Universe , 2003 , pp. 361 - 362
Copyright
Copyright © Astronomical Society of the Pacific 2003 

References

Liu, X., Storey, P.J., Barlow, M.J., & Clegg, R.E.S. 1995, MNRAS, 272, 369 Google Scholar
Peimbert, M. 1967, ApJ, 150, 825 Google Scholar