Retraction Note to: Astrophys. Space. Sci. (2007) 308: 309–316

The authors have retracted this article (McGowan et al. 2007) which was unintentionally submitted in full length as part of a conference proceedings. However, the authors had already published the article in another journal (McGowan et al. 2006). Therefore this article is redundant. All authors agree with this retraction.