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(meteorobs) Re: mass vs. brightness



James,

The following was copied from the IMO'S Visual Handbook (currently out
of print). It should help you visualize the relationship between mass
and brightness for meteoroids of high density (average) and those of low
density (1P Halley).

I hope this helps!

Bob Lunsford    

"The brightness of a meteor strongly depends on its atmospheric entry
velocity. Figures listed Table 1-1 should give a rough idea about he
sizes and masses of meteoroids causing meteors given magnitude (Hughes,
1978).

Table 1-1. Rough scale for some meteoroid parameters (after Hughes,
1978). Below the respective data meteoroids of the 1P/Halley streams
entering the Earth's atmosphere at 66 km/s are given (Hughes, 1987).
Visual Magnitude Meteoroid mass Diameter

Visual Magnitude             +15        +7       0       -7       -15
Average Meteoroid Mass    .0000001g   .0001g   1 gram    100g
1,000,000g   "          " Diameter      100um      1mm     2cm     
20cm   2 meters
1P Halley meteoroid Mass .0000000007g .000001g  .002g  4 grams    ???

James Wray wrote:
> 
> Hi Folks!
> 
> I am curious about the relationship between the brightness of a meteor and
> the mass of the meteoroid that causes it.  I sure would appreciate it if
> someone would point me in the direction of some information on this.  I
> remember years ago plotting a graph for Lincoln LaPaz, as a student
> research assistant, of some representation of this relation but I don't
> remember the formula or have any idea what he was basing that particular
> relation on.  I sort-of remember that it was based on some of his work that
> suggested that a -4 (?) mag meteor was caused by a 4cm3 (?) particle
> (Nickel-Iron?) that would just barely survive the entry ablation.  ie
> anything larger would produce a meteorite.  Of course there were all sorts
> of assumptions and conditions on velocity, etc, etc, which I don't recall.
> What is the latest (anything in the last 40 years or so) info on this sort
> of thing?  Sure would appreciate an update on this!!
> 
> Many Thanks and
> 
> Clear Skys to y'all!!
> 
> Jim Wray
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