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Differential Ablation

 
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Bill W



登録日: 2012.02.13
記事: 129
所在地: Glasgow

記事日時: Fri Dec 02, 2016 1:36 am    記事の件名: Differential Ablation 引用付きで返信

Hi all,
I caught this a short while ago...

https://www.youtube.com/watch?v=YrxxiWbe40Q

This is an effect that I've never seen before! The composite image looked quite normal but it was only when I played the video that it proved to be very unusual.

It appears to separate into to two components. Looking carefully at the video I think there has been either some "fluffy" material or perhaps volatile material ablating before the more robust bulk. The meteor also has some of the characteristics of the "melting" meteors I've been catching.

These are relative terms of course, as the particle will have been very small to start with!

Yet another example of how important video observations are, this would have been completey missed in still imaging!

cheers,
Bill.
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SonotaCo
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登録日: 2004.08.07
記事: 9024
所在地: 139.66E 35.65N

記事日時: Fri Dec 02, 2016 8:23 am    記事の件名: Re: Differential Ablation 引用付きで返信

Hi
Bill W wrote:

https://www.youtube.com/watch?v=YrxxiWbe40Q
This is an effect that I've never seen before!

Wow... yes me too have never seen before, like this.

I have a curiosity about the velocity of two objects.
At a glance, the latter part seems faster.
If so the explanation will be limited to some special reason like...
"Two independent meteors at a very close time. happend in an almost same direction."
Wink Question
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Bill W



登録日: 2012.02.13
記事: 129
所在地: Glasgow

記事日時: Fri Dec 02, 2016 8:46 am    記事の件名: 引用付きで返信

Hi,

It a really interesting effect.

If you watch the meteor really closely the meteor doesn't change speed until burn out.
Try and ignore the "first" fade, that causes the optical illusion because that does slow as it melts.

The meteor proceeds to travel at almost the same speed, until burn out, as before the first fade, just like a normal meteor.

This is why I think it is the same meteor shedding some material. It might be two meteors but the chances of that must be absolutely tiny :-0

However, if it is two meteors it must be an equally rare an event!

Pretty cool Smile)

cheers,
Bill.
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Bill W



登録日: 2012.02.13
記事: 129
所在地: Glasgow

記事日時: Thu Feb 09, 2017 8:40 pm    記事の件名: 引用付きで返信

Hi all,
One observation is a freak but two is the discovery of a new class of meteor phenomena Wink

Caught another separating meteor showing differential ablation.

https://www.youtube.com/watch?v=q59X2xWLGao

Fantastic!

cheers,
Bill.
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登録日: 2004.08.07
記事: 9024
所在地: 139.66E 35.65N

記事日時: Fri Feb 10, 2017 7:02 am    記事の件名: 引用付きで返信

Yes, I agree as a new class, please give a name.
to me, it looks like the superman who casts a suit off and runs away...
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Bill W



登録日: 2012.02.13
記事: 129
所在地: Glasgow

記事日時: Tue Feb 14, 2017 6:15 am    記事の件名: 引用付きで返信

Hi,
Mmmmm, a name?

So perhaps "meteor, class DA" might do.

Some material is being shed first than the remaining material ablates, so I think "differential ablation" correctly describes the effect.

Not very imaginative though... Wink

Maybe the "melting" or fading meteors could be class "SA" for slow or extended ablation. (see https://britastro.org/node/6878 and https://www.youtube.com/watch?v=rKEydn4lTZ8&feature=youtu.be)

Working backwards would give class N for normal, being the more usual rapid onset and fast decay.

Working with narrower fields of view might record fewer meteors but the larger image scale is certainly revealing unusual characteristics. As more meteors are recorded with these distinct effects a whole new video meteor classification scheme could evolve

Not very scientific but perhaps useful for logging purposes.

Cheers,
Bill.
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登録日: 2004.08.07
記事: 9024
所在地: 139.66E 35.65N

記事日時: Tue Feb 14, 2017 7:34 am    記事の件名: 引用付きで返信

Bill's DA, OK thanks.
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Bill W



登録日: 2012.02.13
記事: 129
所在地: Glasgow

記事日時: Wed Mar 08, 2017 5:14 am    記事の件名: 引用付きで返信

In an attempt to better visualise these unusual ablation effects I've mounted 25mm lenses on a couple of cameras.

Caught this perfect example of a melting or dissolving meteor this morning.

https://youtu.be/cvOFgU8CFIA

I think the meteoroid must be fragmenting into many extremely small particles as it penetrates into the atmosphere and appears to simply melt away.

Cheers,
Bill.
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Bill W



登録日: 2012.02.13
記事: 129
所在地: Glasgow

記事日時: Thu Mar 09, 2017 9:44 am    記事の件名: 引用付きで返信

After reviewing the other videos from the same night I discovered I had picked up a "normal" meteor on the same system that caught the dissolving meteor.
To show the variation in ablation charateristics of the different meteorid particles I put together another short YouTube video.

https://youtu.be/y67mQm70dow

cheers,
Bill.
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