334 research outputs found
A Preliminary Analysis of the Shangri-La Bolide on 2017 Oct 4
At 12:07 UT (8:07 pm China Standard Time) on 2017 Oct 4, a bright bolide was
widely observed in the Shangri-La region in the Province of Yunnan, China
(Figure 1). The event was well observed by the general public as it took place
on the night of the Mid Autumn Festival which associates with moon gazing.
Sonic booms and ground shaking were reported in an area about a thousand square
kilometers wide to the northwest of the Shangri-La City. Data from the U.S.
government sensor suggested that the impact energy of the event is
approximately 0.54 kt TNT equivalent, with the terminus of the bolide
positioned at N, E. This is the largest observed
bolide event overland since the bolide event took place in Mauritania on 2016
Jun 27 (1.2 kt). In this Research Note we present a preliminary analysis of
this event.Comment: Earth and Planetary Physics in pres
Ozone Measurements with Meteors: A Revisit
Understanding the role of ozone in the Mesosphere/Lower Thermosphere (MLT)
region is essential for understanding the atmospheric processes in the upper
atmosphere. Earlier studies have shown that it is possible to use overdense
meteor trails to measure ozone concentration in the meteor region. Here we
revisit this topic by comparing a compilation of radar observations to
satellite measurements. We observe a modest agreement between the values
derived from these two methods, which confirm the usefulness of the meteor
trail technique for measuring ozone content at certain heights in the MLT
region. Future simultaneous measurements will help quantifying the performance
of this technique.Comment: MNRAS in pres
Meteor showers from active asteroids and dormant comets in near-Earth space: a review
Small bodies in the solar system are conventionally classified into asteroids
and comets. However, it is recently found that a small number of objects can
exhibit properties of both asteroids and comets. Some are more consistent with
asteroids despite episodic ejections and are labeled as "active asteroids",
while some might be aging comets with depleting volatiles. Ejecta produced by
active asteroids and/or dormant comets are potentially detectable as meteor
showers at the Earth if they are in Earth-crossing orbits, allowing us to
retrieve information about the historic activities of these objects. Meteor
showers from small bodies with low and/or intermittent activities are usually
weak, making shower confirmation and parent association challenging. We show
that statistical tests are useful for identifying likely parent-shower pairs.
Comprehensive analyses of physical and dynamical properties of meteor showers
can lead to deepen understanding on the history of their parents. Meteor
outbursts can trace to recent episodic ejections from the parents, and "orphan"
showers may point to historic disintegration events. The flourish of NEO and
meteor surveys during the past decade has produced a number of high-confidence
parent-shower associations, most have not been studied in detail. More work is
needed to understand the formation and evolution of these parent-shower pairs.Comment: PSS in pres
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