Aims: Prior to 2019, the June epsilon Ophiuchids (JEO) were known as a minor unconfirmed meteor shower with activity that was considered typically moderate for bright fireballs. An unexpected bout of enhanced activity was observed in June 2019, which even raised the possibility that it was linked to the impact of the small asteroid 2019 MO near Puerto Rico. Early reports also point out the similarity of the shower to the orbit of the comet 300P/Catalina. We aim to analyze the orbits, emission spectra, and material strengths of JEO meteoroids to provide a characterization of this stream, identify its parent object, and evaluate its link to the impacting asteroid 2019 MO.
Methods: Our analysis is based on a sample of 22 JEO meteor orbits and four emission spectra observed by the AMOS network at the Canary Islands and in Chile. The meteoroid composition was studied by spectral classification based on relative intensity ratios of Na, Mg, and Fe. Heliocentric orbits, trajectory parameters, and material strengths were determined for each meteor and the mean orbit and radiant of the stream were calculated. The link to potential parent objects was evaluated using a combination of orbital-similarity D-criteria and backwards integration of the orbit of comet 300P and the JEO stream.
Results: We confirm the reports of an unexpected swarm of meteoroids originating in the JEO stream. JEO meteoroids have low material strengths characteristic for fragile cometary bodies, and they exhibit signs of a porous structure. The emission spectra reveal slightly increased iron content compared to all other measured cometary streams, but they are generally consistent with a primitive chondritic composition. Further dynamical analysis suggests that the JEO stream is likely to originate from comet 300P/Catalina and that it was formed within the last 1000 yr. Over longer timescales, the meteoroids in the stream move to chaotic orbits due to the turbulent orbital evolution of the comet. Our results also suggest that the impact of the small asteroid 2019 MO on June 22 was not connected to the JEO activity.