Archive data mining the Lyrids Pavel Koten(1) in cooperation with (1) J. Borovička, P. Spurný, R. Štork, V. Vojáček (2) K. Fliegel, P. Páta, S. Vítek (1) Astronomical Institute ASCR, Ondřejov, Czech Republic (2) Czech Technical University, Prague, Czech Republic Meteoroids 2016 conference, ESA/ESTEC Noordwijk, June 6-10

Lyrid meteor shower annual meteor shower (006 LYR) with variable activity usually peak around April 21-22 (λo ~ 31.6º) occasionally outbursts > 100 meteors/hour parent – C/1861 Thatcher radiant α ~ 272º, δ ~ 33º (Lindblad & Porubcan (1991), Arter & Williams (1997), …) many papers – orbital evolution (enhanced activity - 12years period) – but no physical structure video observations – several campaigns 1998, 1999, 2004, 2006, …, 2014, 2015

Archive and new data archive – analogue video, new – digital cameras (MAIA) both – image intensifier Mullard XX1332, 50mm lens 25 and 61.15 fps 8 and 10 bits simultaneous campaigns in 2014, 2015 usual processing

Atmospheric trajectory calculation Manual measurement and calculation distance of measured points from average trajectory 22.4.2015 19:45:18 UT April Lyrid D = 0.02

Properties of Lyrids beginning heights parameter KB light curves deceleration => meteoroid composition

Beginning heights 73 Lyrid meteors DSH < 0.15 only complete light curves masses: 10-4 ÷ 10-1 g method of Hapgood et al.(1982) increasing with increasing photometric mass slope: k = 3.5 explanation: gradual ablation before reaching of camera’s lim. mag. (Koten et al.,2004)

Comparison with other showers with k = 3.5 almost the same as Quadrantids, but few km higher more compact than Perseids, Taurids, Leonids less than Geminids

Parameter KB One dimensional parameter – eliminates potential effect of different zenith distance of radiant (Ceplecha, 1988) Lyrids: KB = 7.0 ± 0.1 (group C2 – “regular cometary material, long period comets”) Leonids – 6.6 Quadrantids – 7.2 Perseids – 6.8 Geminids – 7.2 Orionids – 6.8 (all using the same video systems)

Light curve shape parameter F (Flemming et al. 1993) symmetrical light curves with maximum around the middle of luminous trajectory (mean F ~ 0.55)

Deceleration 18 Lyrid meteors show deceleration – 15 modeled erosion model (Borovička et al., 2007) was applied (grain density 3000 kg/m3, atm. model NRLMSISE-00) Lyrid meteor 04421047 – good fit of deceleration and light curves

Deceleration II. Lyrid 15422005 – both systems, more points for fitting mass 7x10-3 g grains 8x10-8 to 1,5x10-7 g about 53 500 pcs mass distr. index 2.0

Modeled light curves usually smooth light curves without any flares => complete and continues disintegration into the grains

Erosion heights Erosion starts between 112 and 106 km around 100 km majority of meteoroids completely disintegrated into grains HBE around HB higher / lower by up to few km

Other parameters ablation coefficient σ = 0.0015 – 0.026 erosion coefficient η = 0.025 – 0.57 mean ratio η / σ ~ 23 lower values in comparison with Draconids (Borovička et al. 2007) ES – energy received per unit cross-section prior start of the erosion: from 4.3 x 105 to 5.3 x 106 J/m2 in average higher than in the case of DRA (~ 1 x 106 J/m2)

Grain distribution From 27 000 up to 4x106 grains Mass distribution index 1,8 – 2,8 (for grains)

Grain sizes Usual sizes: 0.01 – 0.3 mm extreme case – range 0.004 – 0.37 mm comparison with: - Draconids – 0.03 to 0.1 mm (LYR larger) - Quadrantids, Geminids – 0.08 to 0.3 mm (Borovička et al., 2010) (LYR grains of similar sizes or smaller)

Summary good quality double station data on >70 Lyrids light curves and height data – similar to QUA, few km higher beginning, more compact that PER, ORI erosion model for 15 meteors grain distribution – generally 10 to 300 μm

Thank you for your attention! Work supported by the Grant Agency of the Czech Republic grant no. 14-25251S