EDP Sciences
Free access
Volume 412, Number 3, December IV 2003
Page(s) 791 - 798
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20031246

A&A 412, 791-798 (2003)
DOI: 10.1051/0004-6361:20031246

The correlation between planetary nebula morphology and radio brightness temperatures

J. P. Phillips

Instituto de Astronomia y Meteorologia, Av. Vallarta No. 2602, Col. Arcos Vallarta, CP 44130 Guadalajara, Jalisco, Mexico
(Received 18 June 2003 / Accepted 8 August 2003)

We have used model central star evolutionary tracks to evaluate the expected variation of 5 GHz brightness temperatures  $T_{\rm B}$ in planetary nebulae. Using these results, and previously derived central star mass functions, we find that there should be a correlation between  $T_{\rm B}$ and the mean central star mass  $\langle M_{\rm CS}\rangle$, and also between  $T_{\rm B}$ and nebular morphology.

An analysis of the available observational results suggests that such a correlation between  $T_{\rm B}$ and nebular morphology does indeed exist. Bipolar nebulae appear to be concentrated towards high brightness temperatures, whilst circular sources tend to possess lower brightness temperature shells. Elliptical sources are present (and common) at all values of  $T_{\rm B}$. There are differences however between the observed and deduced morphological variations, and these enable us to place constraints upon the progenitor masses of the nebulae. In particular, it is clear that higher mass progenitors are likely to give rise to both bipolar and elliptical outflows; a result which is consistent with analyses of nebular abundances, Zanstra temperatures, and line excitations.

Key words: planetary nebulae: general -- ISM: jets and outflows -- stars: evolution

© ESO 2003