High resolution meteor spectrum.

[Bill Ward]

Hi all,

Whilst observing the Perseids one of my HD spectro systems picked up a most interesting spectrum. It had some interesting features that suggested it was something special. It was also extremely bright as I caught the 2nd AND 3rd order!

Checking with the NEMETODE group revealed that several observers had also captured it. It turned out to be a -3 Alpha Cap.

This is a very rare spectrum and it is by far the highest resolution of any meteor spectrum I’ve ever captured.

Below is the crop of the 3rd order. It shows the Mg triplet fully resolved and the Na doublet is also seen to be split. The overall characteristics are of a normal rocky composition. The parent body being 169P/NEAT a comet but also of asteroidal character identified as 2002 EX12 which was found to be weakly active at perihelion and re-named with it’s comet designation.

The sodium line is quite strong so the meteoroid may be relatively “young”.

There are many lines to identify and more analysis to follow.

cheers,

Bill.

Attachments:

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   M20200809_002653_UKKilwinning_P_3rd-order_annot.jpg
   

[Daryl Dobbs]

Just curious when was the spectrum taken as around 23:30 BST on Saturday night a bright red meteor in the west was reported on the Facebook Valleys Astronomy group page. The observation was made from South Wales.

[Bill Ward]

Hi,

Should’ve put the date/time info in the post! No, this was 0026 9th Aug 2020.

Bill.

[Bill Ward]

Hi all,

After further observations by the NEMETODE guys it appears the meteor wasn’t an Alpha Cap. It now looks like a -4 sporadic fireball of asteroidal origin. So it was indeed a normal chunk of rock…

Cheers,

Bill.

[Bill Ward]

Hi,

Here’s a calibrated graph of the spectrum. Had a few headaches with this one as the spectrum isn’t the third order, it’s the second order. A bit of confusion with the image scale after 12+ years of working with spectra from WATECS…

A few “lines”, marked with an * are stellar artifacts and noisy pixels not real lines.

and here’s a list of list of catalogue lines closest to the “barycentre” of the spectrum line (as it’s called in VisualSpec)

Line    Wavelength (nm)        Element

1:    421.618            Fe I
2:    427.176            Fe I
3:    430.790            Fe I
4:    432.576            Fe I
5:    437.593            Fe I
6:    438.355            Fe I
7:    440.475            Fe I
8:    442.730            Fe I
9:    446.165            Fe I
10:    448.113            Mg II
11:    495.760            Fe I
12:    511.040            Fe I
13:    516.732            Mg I (Probable blend with 516.749nm Fe I)
14:    517.268            Mg I (Probable blend with 517.160nm Fe I)
15:    518.360            Mg I
16:    522.715            Fe I
17:    526.954            Fe I
18:    532.830            Fe I

If the spectrum had been a bit brighter, or shifted to either side a bit, perhaps other lines would have been observed. However as is, it looks like a simple composition of just iron, magnesium and sodium.

Interesting because it is rather un-interesting!

Cheers,

Bill.

[Mr Jack Martin]

Bill,

A good result, more interesting than un-interesting !

Well done.

Jack

[Bill Ward]

Hi Jack,

Thanks. I have another very hi res spectrum (the Fe one) now with 60+ lines identified. This is currently with John Mason who wanted something for the Observing Notes in the Journal.

We’ll see what appears in the print but I’ll re-post the spectrum graphs here in due course.

Cheers,

Bill.

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