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(meteorobs) Re: [comet 73P/SW3] Tau Herculids = Alpha Bootids?

Sergey Shanov wrote:

>  Hello John Greaves, Takema Hashimoto and others observers!
>
> I do not have almost doubts, that meteoric showers Tau Herculids and
> Alpha-Bootids belong to one comet (73P/Schwassmann-Wachmann 3). Tau
> Herculids have abandoned a mother comet much earlier and this stream
> with each year weakens. All this is a corollary of variability of an
> orbit of a comet.
>
> Let's compare cometary and meteoric radiants?
>
> THE OBJECT                                           RD(au) RA (deg)
> Decl (deg) Vg
>
> 73P/Schwassmann-Wachmann 3 (1930.06.09)  0.002   221
> +47          13
>
> TauHerculids (1930.06.09)
> 236         +42
>
> 73P/Schwassmann-Wachmann 3 (1979.05.31)  0,05    210
> +32         12
>
> May
> Alpha-Bootids
> ?              ?           ?
>
> Since 1979 the orbit of this comet almost has not varied
>
> On my calculations, minimum distance between orbits (0.05 au) on
> longitudes of the Sun 53,8 - 69,9 deg. It also corresponds yours,
> Takema, observations.
>
> It is known, that the meteor shower shape anomal tail of comets
> (directional to the Sun). In the last appearance the comet
> 73P/Schwassmann-Wachmann 3 has collapsed on fragments up to a
> perihelion. It means, that the fresh meteoric particles have gained
> speed more, than for a mother comet and in 2001 they will come to a
> perihelion behind schedule. I expect, that in 2001 May Alpha-Bootids
> will be appreciable better.
>
> Sergey Shanov

Dear Sergey Shanov

Marvellous stuff!!!  Where have you been all our lives!

I'd noted the break up of 73P/SW3 during its last perihelic apparition,
with the fact of the 1930 tau Herculid event in view, and had tucked it
away at the back of the brain, intending to use the fragments' derived
orbits that will hopefully be computed on their equally hopeful recovery
next year, or sooner, to see what may happen.  It seems, however, that
I'd totally forgot about it too! So thanks to Sergey for the note, and
making a better job of things than I would have!

Anyone else capable of such sums, please also look into this : if
73P/SW3 amounts to nothing meteor outburst-wise after the next
apparition, it'll be just another fairly reasonable false alarm.  If it
happens, and we all more or less miss it just because we didn't think it
through, there'll be a lot of sulking going on [starting with me, for
one]!

Sergey's [and Takema's] work confirms a sneaking suspiscion I've had for
some time : that hidden away in Russian and Japanese texts and data is a
lot of interesting meteor stuff that the English speakers/readers of NW
Europe and N America have little or no inkling of!!!!


OTHER

Re meteoroid burn ups that the list is also noting under the P/2000 G1
LINEAR & Vgeo thread :

I think that some little time ago something similar to this was well
debated and cleared up on a meteorite list.  Could anyone who is aware
of this summarize the conclusions [I'm sure I've seen a posting by one
person who is on both lists]?

I do know that meteorites can "burn" when you pick them up because they
are so _cold_.  That is, very little of the heat gets inside the
meteorite, and it is still as cold as space therein!

As for meteor_oids_ : well, I'm no way near sure of the numbers, but I
think folk are forgetting about _phase changes_.  The meteoroid will
first melt, then boil, then ionise [become a plasma].  All phase changes
take up a lot of energy, with little apparent external effect until the
actual change itself.  Whether these "latent heats" of melting,
vaporisation and ionisation are sufficiently "hungry" enough to absorb
the amounts of energy involved, I dunno [school memories of polystyrene
cups, ice cubes, thermometers, and electric heaters in labs a quarter a
century ago come to mind, so I probably did know the relevant sums
once!], but I did think the "bright" bit of a meteor was the meteoroid
burning up, and the "train/trail" was the atmospheric recombination bit,
at least in "visual" terms.

I'm not sure what relevance this has, but I do know that "specific heats
of conduction" are miniscule, energy requirements- [and absorption-]
wise, compared to "specific latent heats of phase change"... ...the
quotes are because I wouldn't be surprised if the terminology has
changed nowadays.

Cheers

John

John Greaves
UK


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