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Spectral index of the H2O-maser-emitting planetary nebula IRAS 17347-3139


Gomez, JF and de Gregorio-Monsalvo, I and Lovell, JEJ and Anglada, G and Miranda, LF and Suarez, O and Torrelles, JM and Gomez, Y, Spectral index of the H2O-maser-emitting planetary nebula IRAS 17347-3139, Monthly Notices of the Royal Astronomical Society, 364, (2) pp. 738-742. ISSN 0035-8711 (2005) [Refereed Article]

DOI: doi:10.1111/j.1365-2966.2005.09592.x


We present radio-continuum observations of the planetary nebula (PN) IRAS 17347-3139 (one of the only two known to harbour water maser emission), made to derive its spectral index and the turnover frequency of the emission. The spectrum of the source rises in the whole frequency range sampled, from 2.4 to 24.9 GHz, although the spectral index seems to decrease at the highest frequencies (0.79 ± 0.04 between 4.3 and 8.9 GHz, and 0.64 ± 0.06 between 16.1 and 24.9 GHz). This suggests a turnover frequency of around 20 GHz (which is unusual among PNe, whose radio emission usually becomes optically thin at frequencies <10 GHz), and a relatively high emission measure (1.5 × 10 9 cm -6 pc). The radio-continuum emission has increased by a factor of ≃1.26 at 8.4 GHz in 13 yr, which can be explained as expansion of the ionized region by a factor of ≃1.12 in radius with a dynamical age of ≃120 yr and at an expansion velocity of ≃5-40km s -1. These radio-continuum characteristics, together with the presence of water maser emission and a strong optical extinction, suggest that IRAS 17347-3139 is one of the youngest PNe known, with a relatively massive progenitor star. © 2005 RAS.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Lovell, JEJ (Dr Jim Lovell)
ID Code:46653
Year Published:2005
Web of Science® Times Cited:11
Deposited By:Physics
Deposited On:2007-08-28
Last Modified:2007-08-28

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