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(meteorobs) speed & brighntess (Re (2): "CLOSEST FLYBY EVER")



> Of
> course much more depends on velocity of entry Vinf: Peekskill
> was only traveling at 15km/s. Maybe this would've been faster?

No, it's slower:

Peekskill:  Vgeo 10.1 km/s   Vini 14.7  km/s

2004 FH:  Vgeo  6.9  km/s   Vini 13.2 km/s

If I take a peek in Hills & Choda ( Astron. J. 105 (1993), 1114-1144) for
indications, then an ~ 20 meter diameter object with this speed results in a
fireball brightness of order -25 magnitude, depending a bit (but not too
much) on composition.

It would violently fragment in the atmosphere too. Depending on its
composition, the largest surviving fragments (apart from a shower of dust
and smaler fragments in large quantities!) would be in the order of several
kg's for a stone, a few grams for a soft stone, and only if it is an iron,
very large fragments of several tons weight would come down. None of it
would still have cosmic speeds at impact except for the case of an iron,
which would it with approximately 10 km/s. Stones would in fact largely
disintegrate in this size-speed range.

Note that these are only very rough indications.

- Marco

------
Dr Marco Langbroek
Dutch Meteor Society (DMS)
Leiden, the Netherlands
52.15896 N, 4.48884 E (WGS 84)

e-mail: meteorites@dmsweb.org
DMS website: http://www.dmsweb.org
priv. website: http://home.wanadoodot nl/marco.langbroek
------

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