Activity of the 2013 Geminid meteoroid stream at the Moon

作者：Szalay Jamey R.; Pokorny Petr; Jenniskens Peter; Horanyi Mihaly^*

来源：Monthly Notices of the Royal Astronomical Society, 2018, 474(3): 4225-4231.

DOI：10.1093/mnras/stx3007

• meteorites, meteors, meteoroids
• Moon

The Lunar Dust Experiment (LDEX) onboard the Lunar Atmosphere and Dust Environment Explorer mission orbited the Moon from 2013 October to 2014 April and detected impact ejecta generated by the continual bombardment of meteoroids to the lunar surface. While the Moon transited the Geminid meteoroid stream, LDEX observed a large enhancement in the lunar impact ejecta cloud, particularly above the portion of lunar surface normal to the Geminids radiant. Here, we present the LDEX measurements during the Geminids, using the surface density of impact ejecta at the Moon as a proxy for meteoroid activity. We find two peaks during the Geminids, a smaller peak at solar longitude lambda(circle dot) = 261 degrees.3 +/- 0 degrees.12 followed by a larger peak at lambda(circle dot) = 262 degrees.2 +/- 0 degrees.12, with a surface density ratio of 2.6 between the two. Both peaks coincide with radar observations of shallower mass indices than most of the Geminids, suggesting an enhancement of larger particles during the two peaks. The total duration of the 2013 Geminid meteoroid shower at the Moon measured by LDEX is Delta lambda(circle dot) = 1 degrees.7 for activity > 10 per cent of the peak value, corresponding to a width of 1.9 x 10(6) km normal to the Geminids velocity vector. The timing of the main observed peak matches ground-based visual observations of meteors with magnitude of -1 to -3 and suggests LDEX is detecting ejecta from primary impactors with radii similar to 2 mm to 2 cm during this time.

• 出版日期2018-3