This research was triggered by an observing program of the Australia Telescope Compact Array called ATESE, designed to detect extreme scattering events (ESEs) that cause flux modulations and scattering angles more than those typically associated with the interstellar medium (known as interstellar scintillations). The observations are also sensitive to short-period, large-amplitude events (IDVs) like the twinkling described above. In the course of the program, the observers detected an IDV towards quasar PKS 1322-110 and then noticed its coincident star, Spica. Two further IDVs towards quasars have been studied on longer timescales (not as part of ATESE), and it is these that Walker et al. used to bolster their theory: PKS 1257-326 (with star Alhakim) and J1819+3845 (with Vega).
Despite the tantalizing nature of Walker et al.'s explanation, there is an issue with the analogy: the Helix Nebula is an evolved star that was previously surrounded by a clumpy circumstellar envelope. Vega and Alhakim are main-sequence stars and are not expected to be embedded in dense circumstellar media. Thus the origin of the plasma filaments in these cases is not clear; Walker et al. suggest that the globule-like structures are long-lived and formed contemporaneously with their stars. Alternatively they may be left-overs from an unconventional star formation process: molecular clumps that did not coalesce with others to form stars. Further study of the environments around these stars, for instance by imaging molecular emission lines of H2 or CO, may help to cement the explanation behind these glittering galactic nuclei.
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