학술논문
The Winchcombe Fireball -- that Lucky Survivor
Document Type
Working Paper
Author
McMullan, Sarah; Vida, Denis; Devillepoix, Hadrien A. R.; Rowe, Jim; Daly, Luke; King, Ashley J.; Cupák, Martin; Howie, Robert M.; Sansom, Eleanor K.; Shober, Patrick; Towner, Martin C.; Anderson, Seamus; McFadden, Luke; Horák, Jana; Smedley, Andrew R. D.; Joy, Katherine H.; Shuttleworth, Alan; Colas, Francois; Zanda, Brigitte; O'Brien, Áine C.; McMullan, Ian; Shaw, Clive; Suttle, Adam; Suttle, Martin D.; Young, John S.; Campbell-Burns, Peter; Kacerek, Richard; Bassom, Richard; Bosley, Steve; Fleet, Richard; Jones, Dave; McIntyre, Mark; James, Nick; Robson, Derek; Dickinson, Paul; Bland, Philip A.; Collins, Gareth S.
Source
Subject
Language
Abstract
On February 28, 2021, a fireball dropped $\sim0.6$ kg of recovered CM2 carbonaceous chondrite meteorites in South-West England near the town of Winchcombe. We reconstruct the fireball's atmospheric trajectory, light curve, fragmentation behaviour, and pre-atmospheric orbit from optical records contributed by five networks. The progenitor meteoroid was three orders of magnitude less massive ($\sim13$ kg) than any previously observed carbonaceous fall. The Winchcombe meteorite survived entry because it was exposed to a very low peak atmospheric dynamic pressure ($\sim0.6$ MPa) due to a fortuitous combination of entry parameters, notably low velocity (13.9 km/s). A near-catastrophic fragmentation at $\sim0.07$ MPa points to the body's fragility. Low entry speeds which cause low peak dynamic pressures are likely necessary conditions for a small carbonaceous meteoroid to survive atmospheric entry, strongly constraining the radiant direction to the general antapex direction. Orbital integrations show that the meteoroid was injected into the near-Earth region $\sim0.08$ Myr ago and it never had a perihelion distance smaller than $\sim0.7$ AU, while other CM2 meteorites with known orbits approached the Sun closer ($\sim0.5$ AU) and were heated to at least 100 K higher temperatures.
Comment: Accepted for publication in MAPS
Comment: Accepted for publication in MAPS