The distances of less‐evolved planetary nebulae: a further test of statistical distance scales

It has recently been pointed out that a number of the methods used to determine planetary nebulae (PNe) distances may be appreciably in error. Whilst the scales of Zhang (1995), Bensby & Lundstrom (2001) and others are appropriate for higher radio brightness temperatures T B , those of Phillips and Daub are more relevant where T B is small. We note, in the following, that the absolute bolometric magnitudes of less‐evolved PNe are likely to be similar. The mean value of 〈 M BOL 〉 can therefore be used to constrain PNe distances D , and confirm the distance scales for higher T B outflows. We have used this procedure to evaluate distances to a further 47 PNe, and we find that the mean values of 〈 D 〉 are consistent with those of Cahn, Kaler & Stanghellini (1992), Zhang (1995), Phillips et al. (2004) and van de Steene & Zijlstra (1995). They are, as expected, inconsistent with the lower T B scale of Phillips (2002a).