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Re:(Meteorobs)Derived Mass via Magnitude (was Astrobio/ Visual perception/LEBs)

Thanks Jim and Nick!
My post is cross list because I am calling on both lists for assistance.

Now if I get my brain engaged right,  it would seem that with a
magnitude I can derive wattage.  With wattage,  I can convert to joules
and with joules I can get a matrix of velocity and mass combinations at
a given power level....  This is Great!!!  Does anyone know the joules
generated by one gram at one kilometer per second?    From Piper's post
a while back I have something in terms of calories. 

Can someone help me work this backwards to derive mass or at least
joules? (from which I could put together a table of mass/velocity
combinations associated with a given magnitude).
 
Piper wrote:
>> Kathleen Mark's excellent book "Meteorite Craters" has a very
enlightening table on page 53, with data borrowed from a study of the
kinetics of meteorite impact made in 1924 by A.C. Gilford. Here is some
info excerpted from that table:

Kinetic energy of meteorite (calories per gram):

1 mile per second           310
5 miles per second         7745
10 miles per second       30980
20 miles per second      123900
40 miles per second      494700>>



Regards,
Elton Jones




Jim Richardson wrote:
> 
> Hello again,
> 
> In flipping through my notes today on magnitude correction factors, I found
> something which might be of interest in this discussion of bio-luminescence
> in the upper atmosphere.
> 
> McKinley (1961) quotes from Opik (1955) to give a "standard candle" for
> absolute meteor magnitude verses power output in Watts.  Opik states that a
> 1 Watt luminosity meteor at 100 km altitude would have a visual magnitude
> of 6.8.  This can be used to give us a meteor absolute magnitude equation:
> 
> Ma = 6.8 - 2.5*log(La)
> 
> or La = 10^((6.8 - Ma) / 2.5)
> 
> Using this last formula gives:
> 
> meteor magnitude, power (Watts)
> m = 6.8,  1.0 W
> m = 6.0,  2.1 W
> m = 5.0,  5.2 W
> m = 4.0,  13 W
> m = 3.0,  33 W
> m = 2.0,  83 W
> m = 1.0,  210 W
> m = 0.0,  530 W
> m = -1.0,  1300 W
> m = -2.0,  3300 W
> m = -3,  8300 W
> m = -4.0,  21,000 W
> 
> Note also that a meteor is a moving point source (from our perspective),
> and is much more likely to be noticed than something diffuse and not
> moving.  Recall looking for those faint "fuzzies" in a telescopic
> eyepiece...those faint stars stand out much better than the Owl Nebula or
> something like it.  Although Dave's proposed critters are a bit closer (45
> miles = 72 km), and would need only about 1/2 the power of the meteors
> above (as a concentrated point source), I don't know of these types of
> power outputs are possible.
> 
> However, I did find the above interesting although I am not sure how well
> Opik's figures continue to hold up.  Just a thought...
> 
> Take care,
> 
>      Jim
> 
> P.S.  I looked again at the D = h*sec(ZA) approximation for meteor distance
> (D) vs altitude (h) and zenith angle (ZA).  From this I found that the
> earlier magnitude correction equations are good down to a radiant altitude
> of about 10 degrees (ZA = 80 deg), a bit better than I thought initially.
> Below this, however, they blow up badly as an approximation.
> 
> Also, I got my greater than and less than symbols crossed at the end of my
> presentation.  The range for the cos(ZA) term should be:
> 
> 0 deg <= ZA <= 80 deg
> 
> James Richardson
> Tallahassee, Florida
> richardson@digitalexp.com
> 
> Operations Manager / Radiometeor Project Coordinator
> American Meteor Society (AMS)
> http://www.serve.com/meteors/


> Nick Martin wrote:
> 
> Sorry this is delayed I had to get hold of the light conversion factors.
> Jim Richardson posted these figures for power output from meteors and I have
> built on them to suggest a test for Dave English to apply to his
> bioluminescence hypothesesis
> 
> >In flipping through my notes today on magnitude correction factors, I found
> >something which might be of interest in this discussion of bio-luminescence
> >in the upper atmosphere.
> >
> >McKinley (1961) quotes from Opik (1955) to give a "standard candle" for
> >absolute meteor magnitude verses power output in Watts.  Opik states that a
> >1 Watt luminosity meteor at 100 km altitude would have a visual magnitude
> >of 6.8.  This can be used to give us a meteor absolute magnitude equation:
> >
> >Ma = 6.8 - 2.5*log(La)
> >
> >or La = 10^((6.8 - Ma) / 2.5)
> >
> >Using this last formula gives:
> >
> >meteor magnitude, power (Watts)
> >m = 6.8,  1.0 W
> >m = 6.0,  2.1 W
> >m = 5.0,  5.2 W
> >m = 4.0,  13 W
> >m = 3.0,  33 W
> >m = 2.0,  83 W
> >m = 1.0,  210 W
> >m = 0.0,  530 W
> >m = -1.0,  1300 W
> >m = -2.0,  3300 W
> >m = -3,  8300 W
> >m = -4.0,  21,000 W
> >Note also that a meteor is a moving point source (from our perspective),
> >and is much more likely to be noticed than something diffuse and not
> >moving.  Recall looking for those faint "fuzzies" in a telescopic
> >eyepiece...those faint stars stand out much better than the Owl Nebula or
> >something like it.  Although Dave's proposed critters are a bit closer (45
> >miles = 72 km), and would need only about 1/2 the power of the meteors
> >above (as a concentrated point source)
> 
> Using these figures  from Jim to very crudely calculate the biomass needed
> to produce David's bioluminescent clouds
> 
> Assuming a typical type of earth bioluminescent system which yield one
> photon/ ATP molecule
> (ATP is {roughly} the cellular energy carrier)
> Using the conversion factor for watt to photons of visible light used in
> studies of photosynthesis
> 1 W =  4.66 microEinsteins-1 =2.9X10^18 photons (1 Einstein=1 mole
> photon=6.23X10^23photons)
> Taking a barely visible extended source as resembling M33 in brightness and
> size roughly mag6 and 1 degree across.
> A magnitude 6 source is radiating 2.1 watts or 6X10^18 photons/sec.
> So the bioluminescent organisms are transforming 6X10^18 molecules of ATP
> per second.
> A rough calculation suggests about 10^5 molecules of ATP per typical
> bacterial cell
> Assuming that the cells turn over their ATP at a rate so they can spare an
> amount equal to all their content for light production every second the
> number of cells involved would be 6 X 10^13
>  weighing roughly 10 g.
> 
> Assuming a cloud this size has about 1km cross section and giving it a 1 km
> depth this implies a microbe content of 10^7 microbes/cubic metre weighing
> about 10 microgrammes.
> 
> This gives a testable feature to the bioluminescece hypothesis.
> Since these clouds would be sedimenting down to lower altitudes does the
> measured particulate content of the highest altitude measurements made match
> these sorts of levels or even approach within a factor of 100, a reasonable
> error margin for these very crude calculations?
> Over to you Dave.
> 
> Nick
> Nick Martin, Bonnyton House, By Ayr, Ayrshire KA6 7EW ,Scotland, UK.
>  Latitude 55 24'56" Longtitude 4 26' 00".
> "Eppur si muove" Galileo Galilei

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