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Differential Ablation
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Bill W



登録日: 2012.02.13
記事: 182
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: 12653
所在地: 139.67E 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: 182
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: 182
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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SonotaCo
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登録日: 2004.08.07
記事: 12653
所在地: 139.67E 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: 182
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: 12653
所在地: 139.67E 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: 182
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: 182
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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Bill W



登録日: 2012.02.13
記事: 182
所在地: Glasgow

記事日時: Fri Jan 04, 2019 12:22 am    記事の件名: 引用付きで返信

Hi,

As well as the meteors that seem to split I've been capturing a lot that seem to melt out of existence. These are perhaps related due to their structure.

I finally captured a decent spectrum of one of these the other night. Perhaps unsurprisingly a stony characteristic was revealed, the main elements being Mg and Na with Fe lines being nicely resolved.

There just might be the hint of some fragmentation seen in the video but it's difficult to be sure as the cropped video also reveals the noise! Whatever the source the meteoroid must have had a weak or fractured structure to fall apart in this manner.

Perhaps a "dustball" as they have been called.

https://youtu.be/XLveGtJsvk4

A happy new year to all,
Cheers,
Bill.
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Bill W



登録日: 2012.02.13
記事: 182
所在地: Glasgow

記事日時: Thu Feb 06, 2020 6:41 am    記事の件名: 引用付きで返信

Hi All,

Caught this very interesting disintegrating meteor last night. Seems to break up, then the cloud of debris brightens very slightly before fading away behind faster moving material.

Cheers,
Bill.

https://youtu.be/V7_aYpJ36MU
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前田



登録日: 2004.09.01
記事: 2754
所在地: Miyazai JAPAN (E131.4, N31.8)

記事日時: Sat Feb 29, 2020 10:12 pm    記事の件名: 引用付きで返信

Hi Bill,

I thought your recent video was a great image with distinct features.

I am observing in full HD video format. Nothing as characteristic as your image has been captured yet. However, because of the high resolution, the process of melting is well clearly visible.

Please take a look at two of my observations.

Koji



M20191217_235126_JPMZ1_HT_2speed.mp4
 説明:
SONY a7s + 85mmF1.2 1860 x 1080 59.94p
normal speed and 1/2 slow speed movie

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M20200224_200728_JPMZ1_HT_2speedH.mp4
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SONY a7s + 400mmF2.8 1860 x 1080 59.94p
normal speed and 1/4 slow speed movie

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藤原康徳



登録日: 2004.08.10
記事: 2683
所在地: 大阪市淀川区

記事日時: Sun Mar 01, 2020 1:01 am    記事の件名: 引用付きで返信

Hi, Koji san,

I show meteor images with characteristics similar to those observed by Koji san.
The meteor was captured simultaneously by video camera systems with 6mm and 85mm lenses.

Yasunori Fujiwara, PhD.



M20191002_012126_Osaka04_NE6.mp4
 説明:
WAT-902H2U + 8mm F0.8

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M20191002_012126_JPOsaka04_85.mp4
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前田



登録日: 2004.09.01
記事: 2754
所在地: Miyazai JAPAN (E131.4, N31.8)

記事日時: Mon Mar 02, 2020 12:54 am    記事の件名: 引用付きで返信

Hi Yasunori

It is a very beautiful image.
You can also clearly see the elongated light emitting part.

Koji
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Bill W



登録日: 2012.02.13
記事: 182
所在地: Glasgow

記事日時: Mon Mar 02, 2020 9:58 pm    記事の件名: 引用付きで返信

Hi Yasunori,

Your video's are excellent! I wish I had one of these Sony camera's!

This new technology is allowing us to explore meteors as never before.

I find the dynamics fascinating and I'm looking forward to seeing more of your captures.

Best Regards,

Bill.

Very Happy
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