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

journal contribution
posted on 2023-05-16, 19:46 authored by Gomez, JF, de Gregorio-Monsalvo, I, James LovellJames Lovell, Anglada, G, Miranda, LF, Suarez, O, Torrelles, JM, Gomez, Y
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.

History

Publication title

Monthly Notices of the Royal Astronomical Society

Volume

364

Pagination

738-742

ISSN

0035-8711

Department/School

School of Natural Sciences

Publisher

Blackwell Publishing

Place of publication

Oxford, England

Repository Status

  • Restricted

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Expanding knowledge in the physical sciences

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