Meteoroid rotation and fireball flickering: a case study of the Innisfree fireball

Some 5 per cent of bright meteors show rapid, quasi-periodic brightness var iations. It is argued that this effect, observationally known as flickering , is a manifestation of the rotational arg modulation of surface mass loss through ablation of a non-spherical meteoroid. We develop a set of time-dep endent, single-body ablation equations that include the effect of cross-sec tion area modulation. We present a discussion of the effects that the rotat ion of a non-spherical meteoroid has on the resultant meteor light curve, a nd we took in depth at the data related to the fireball associated with the fall of the Innisfree meteorite. We find that the parent object to the Inn isfree meteorite was spinning at a rotation frequency of 2.5 Hz when it enc ountered the Earth's upper atmosphere. We also find that the Innisfree pare nt body had an initial mass of about 20 kg and that the ratio of its semimi nor and semimajor axes was about 0.5.