Phillips, J. P.; White, G. J. and Richardson, K. J.
PDF (Version of Record)
- Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
|Google Scholar:||Look up in Google Scholar|
We present spectra and mapping for NGC 7072 in the J = 3→2 and J = 2→1 transitions of CO. The central profile at J = 2→1 is shown to be very similar to the J = 1→0 spectrum measured by Thronson (1983), and this implies a source expansion at roughly constant velocity. The J = 3→2 line however appears weaker, with evidence for appreciable quenching of the higher velocity components. Detailed modelling f the source indicates that densities n must vary appreciably with shell radius R(as nα R-a, where α≥2), and this leads to a corresponding steep radial decrease in the radiation temperature TR. In consequence, the source FWHM is found to decrease appreciably iwth increasing transition frequency, a trend which appears also to be confirmed by our central J = 3→2 scans. It is not however possible to constrain gas kinetic tempertures TK, the level of CO thermalisation, or shell mass M with any degree of confidence - both low and high mass models appear capable of replicating our spectra. Finally, the J = 2→1 spatial velocity map displays evidence for a decrease in velocity width towards the outer regions of the nebula; a feature which is expected of most outflow models. The J = 3→2 map also indicates the presence of a nebular extension to the north-west of the peak emission core, although this is not reproduced in the corresponding J = 1→0 map of Mufson et al. (1975).
|Item Type:||Journal Article|
|Copyright Holders:||1985 European Southern Observatory|
|Keywords:||astronomical maps; astronomical spectroscopy; carbon monoxide; line spectra; planetary nebulae; astronomical models; spatial distribution; velocity distribution|
|Academic Unit/Department:||Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||G. J. White|
|Date Deposited:||07 Jun 2012 15:47|
|Last Modified:||04 Aug 2016 12:45|
|Share this page:|
Download history for this item
These details should be considered as only a guide to the number of downloads performed manually. Algorithmic methods have been applied in an attempt to remove automated downloads from the displayed statistics but no guarantee can be made as to the accuracy of the figures.