VLA observations at 7 mm of the planetary nebula IC 4997

DOI: 
10.1046/j.1365-8711.2002.05843.x
Publication date: 
11/11/2002
Main author: 
Gomez, Y
IAA authors: 
Miranda, LF
Authors: 
Gomez, Y; Miranda, LF; Torrelles, JM; Rodriguez, LF; Lopez, JA
Journal: 
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Publication type: 
Article
Volume: 
336
Pages: 
1139-1142
Number: 
Abstract: 
We present high angular resolution (0.1 arcsec) VLA observations at 7-mm wavelength towards the bipolar planetary nebula IC 4997. The 7-mm emission in IC 4997 is dominated by a bright, compact core, the flux density of which at this wavelength is about six times brighter than at 2.0 and 3.6 cm. We model the centimetre and millimetre continuum spectrum in terms of free-free emission from an ionized core-halo source. In this model a dense (2.6 x 10(6) cm(-3)), optically thick inner core dominates the millimetre emission, while a low-density (1 x 10(4) cm(-3)), optically thin halo dominates the centimetre emission. The spectral index of the core (between 2 cm and 7 mm) is alpha similar or equal to 1.6 +/- 0.1 (S(nu) proportional to nu(alpha)), which is consistent with optically thick free-free emission. An upper limit for the mass-loss rate that created this inner core is similar to3 x 10(-6) M(.) yr(-1), suggesting that this core may have been formed at the end of the superwind phase.
Database: 
WOK
SCOPUS
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2002MNRAS.336.1139G/abstract
ADS Bibcode: 
2002MNRAS.336.1139G
Keywords: 
ISM : jets and outflows; planetary nebulae : individual : IC 4997; radio continuum : ISM