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

Rubin, RH; Bhatt, NJ; Dufour, RJ; Buckalew, BA; Barlow, MJ; Liu, XW; Storey, PJ; ... Martin, PG; + view all (2002) Temperature variations from Hubble Space Telescope imagery and spectroscopy of NGC 7009. Monthly Notices of the Royal Astronomical Society , 334 (4) pp. 777-786. 10.1046/j.1365-8711.2002.05567.x. Green open access

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Abstract

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 (tA2)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 tA2 throughout. Our STIS data allow an even more direct determination of Te and tA2, 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; tA2 is 0.0035. The measurements of Te reported here are an average along each line of sight. Therefore, despite finding remarkably low tA2, 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.

Type: Article
Title: Temperature variations from Hubble Space Telescope imagery and spectroscopy of NGC 7009
Open access status: An open access version is available from UCL Discovery
DOI: 10.1046/j.1365-8711.2002.05567.x
Publisher version: https://doi.org/10.1046/j.1365-8711.2002.05567.x
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: ISM: abundances, ISM: atoms, ISM: individual: NGC 7009, planetary nebulae: general 1 Introduction
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10096023
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