Photo-ionization induced rapid grain growth in novae

¹ Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Pisa 56127, Italy
² Department of Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455, USA e-mail: gehrz@astro.umn.edu

Corresponding author: S. N. Shore, shore@df.unipi.it

Received: 29 August 2003
Accepted: 9 December 2003

Abstract

An elementary model is developed for grain growth during the expansion stage of nova ejecta. Rather than suppressing grain formation, we argue that agglomeration of atoms by dust nuclei proceeds kinetically through induced dipole reactions in a partially ionized medium. Ionization of a cluster increases once the ejecta become transparent in the ultraviolet which triggers runaway grain growth. This mechanism may also be important in other dust-forming hot stars such as Luminous Blue Variables and Wolf-Rayet systems.