Lunar exosphere dynamics at the north pole following Perseid 2009 meteoroid impacts

TL;DR

This study models lunar exosphere Na atom dynamics post-Perseid impacts, linking meteoroid activity to observed Na emissions and developing a 25,000-year meteoroid stream activity model.

Contribution

Introduces a comprehensive model connecting Perseid meteoroid impacts with lunar exosphere Na variations, including a 25,000-year meteoroid stream analysis.

Findings

Na emission intensities increased during Perseid peak

Best model fit with impact temperature of 3000 K

Identified meteoroid streams correlating with Na enhancements

Abstract

Observations of the lunar exosphere provide valuable insights into dynamic processes affecting the Moon, such as meteoroid bombardment. The Chamberlain model was employed to estimate the zenith column density and temperature of Na atoms on August 13/14, 2009, after the peak of the Perseid meteor shower. Additionally, the column density and temperature of Na atoms delivered to the lunar exosphere by gradual processes during the peak on August 12/13, 2009, were estimated. Expected ratios of line-of-sight column densities of Na atoms at three observed altitudes on August 12/13, 2009, were obtained using the Chamberlain model and Monte Carlo simulations. The heightened intensities of Na emission lines on August 12/13, 2009, are attributed to the onset of the third short-term peak in Perseid activity predicted by celestial mechanics. The best agreement between observations and theoretical models was achieved with a theoretical temperature of 3000 K for impact-produced Na atoms. This third peak of Perseids began between 23:29 and 23:41 UT on August 12, 2009, lasting approximately 83 minutes, with a mass flux attributed to the Perseids ranging between 1.6 x 10^-16 and 5 x 10^-16 g cm^-2 s^-1. Additionally, depletion of Li content compared to Na content in the lunar exosphere was detected. A model predicting Perseid meteoroid stream activity on the Moon was developed and compared with spectral observations of the lunar exosphere. By modeling 25,000 years of comet 109P/Swift-Tuttle's orbits, 175 cometary trails likely to have generated meteoroids near Earth and the Moon during the Perseid 2009 meteor shower were identified. Our results reveal annual maxima inducing filament trail structures, one of which closely aligned with the observed peak of increased Na content in the lunar exosphere.