The origin of the strings in the outer regions of η Carinae

Abstract

The narrow optical filaments (`strings' or `spikes') emerging from the Homunculus of η Carinae are modelled as resulting from the passage of ballistic `bullets' of material through the dense circumstellar environment. In this explanation, the string is the decelerating flow of ablated gas from the bullet. An archive Hubble Space Telescope image and new forbidden-line profiles of the most distinct of the strings are presented and discussed in terms of this simple model.