A study on the population index of meteor showers

Chih-Ming Lin^1*, I-Ching Yang¹

¹Department of Applied Science, National Taitung University, Taitung, Taiwan

* Presenter:Chih-Ming Lin, email:cmlin@nttu.edu.tw

We analyzed the annual magnitude cumulative distribution of the meteor showers PER, GEM, QUA, and ORI from 2008 to 2022, using data from the SonotaCo Network Simultaneously Observed Meteor Data Sets in Japan. To obtain the corresponding population index r (defined as the ratio between the number of meteors with magnitude m+1 and the number with magnitude m), we fitted specific region of the magnitude cumulative distribution using the exponential function N_c(m) = Cr^m, where N_c(m) represents the number of meteors with a magnitude less than or equal to m, and C is a constant. The results show that the r-values of different meteor showers are closely related to their parent bodies. For example, GEM and QUA, whose parent bodies are both asteroids, have r-values greater than 2.30, whereas PER, whose parent body is the comet 109P/Swift-Tuttle, has an r-value less than 2.30. For ORI, whose parent body is the comet 1P/Halley, the r-value spans 2.30. Comet 1P/Halley, due to its shorter period (compared to comet 109P/Swift-Tuttle), is significantly influenced by the Sun, causing the parent body to easily lose volatile materials. The meteoroids forming ORI, derived from the surface or internal fragmentation of this parent body, thus contain both volatile and non-volatile particles, with the former resembling the primary cometary material and the latter resembling asteroidal material.

Keywords: meteor, population index, magnitude cumulative distribution