Finite Lifetime Fragment Model 3 for striae formation in the dust tails of comets (FLM 3)

Fine-scale structure in cometary dust tails II: Further evidence for a solar wind influence on cometary dust dynamics from the analysis of striae in comet C/2011 L4 Pan-STARRS

“…This provides a good match to observational data (Pittichová et al, 1997), but the required physical properties of dust are difficult to explain. Nishioka and Watanabe (1990), Nishioka (1998) and Nishioka (2021) instead suggest a continuous cascade of striae formation, which relaxes the constraints on dust properties, but has alleged problems explaining stria shapes (Sekenina and Pittichová, 1997). Other potential mechanisms include optically thick dust clouds (Froehlich and Notni, 1988;Notni and Thaenert, 1988), or the destruction of macroscopic sized (10-100 m) boulders by rotational stresses (Steckloff and Jacobson, 2016).…”

“…This result is in much better agreement with the Nishioka (1998), Nishioka and Watanabe (1990), Nishioka (2021) ''cascade'' striae formation model than the Sekanina and Farrell (1980) two-step process. We also note the most recent version of this ''cascade'' model (Nishioka, 2021) is able to incorporate Lorentz force effects into its description of dust dynamics.…”

“…If original striae form through a multiple stage fragmentation i.e. as per Nishioka (2021) or Steckloff and Jacobson (2016), each stria may contain sub structure; when following the last occurrence of fragmentation, daughter dust of varying 𝛽 𝑟 spreads out over one part of the stria to form a ''sub-stria'' structure. Crossing the HCS causes each of these ''sub-stria'' to undergo an orientation change -as detailed in Horanyi and Mendis (1987) -and these re-orientated ''sub-stria'' form combed features.…”

“…In observing striae formation for this first time and considering the sunward radial alignment of features it appears that the shadowing hypothesis of Froehlich and Notni (1988) may be important. Additionally the interleaved nature of the HCS crossing reorganisation process suggests that models which allow for more mixed dust properties along a stria are more accurate such as those by Nishioka and Watanabe (1990), Nishioka (1998), andNishioka (2021). Valuable data from the Rosetta mission have yet to make their way into the literature on this topic of macroscopic features in extensive dust tails.…”