Temperature variations from Hubble Space Telescope imagery and spectroscopy of NGC 7009

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, J. P. Harrington, P. G. Martin

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


We present new Hubble Space Telescope (HST)/WFPC2 imagery and STIS long-slit spectroscopy of the planetary nebula NGC 7009. The primary goal was to obtain high spatial resolution of the intrinsic line ratio [O III] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (t2A) across the nebula. The WFPC2 Te map is rather uniform; almost all values are between 9000-11 000 K, with the higher Te values closely coinciding with the inner He++ zone. The results indicate very small values -≲0.01 - for t2A throughout. Our STIS data allow an even more direct determination of Te and t2A, albeit for a much smaller area than with WFPC2. We present results from binning the data along the slit into tiles that are 0.5-arcsec square (matching the slit width). The average [O III] temperature using 45 tiles (excluding the central star and STIS fiducial bars) is 10 139 K; t2A is 0.0035. The measurements of Te reported here are an average along each line of sight. Therefore, despite finding remarkably low t2A, we cannot completely rule out temperature fluctuations along the line of sight as the cause of the large abundance discrepancy between heavy element abundances inferred from collisionally excited emission lines compared to those derived from recombination lines.

Original languageEnglish
Pages (from-to)777-786
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Aug 21 2002


  • ISM: abundances
  • ISM: atoms
  • ISM: individual: NGC 7009
  • Planetary nebulae: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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