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Evolution of the coma spectra of C/2020 F3 (NEOWISE)

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#1 mwr

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Posted 31 July 2020 - 07:27 AM

The sequence shows the evolution of the coma-spectra of NEOWISE that were obtained with the SA-100 as objective grating (Fuji X-A1; Canon FD 200 mm). The corresponding pictures were taken using the same equipment without the objective grating.

 

coma_spectra.jpg

 

Has somebody recorded the evolution of the tail-spectra ?  According to the different colors of the tail there should be changes in the corresponding spectra as well.


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#2 descott12

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Posted 31 July 2020 - 08:03 AM

Wow. Very interesting. What do think is causing the Na peak in the just the center image?



#3 sharkmelley

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Posted 31 July 2020 - 08:33 AM

Nice work!   

It's very interesting to see the changes in coma colour alongside the spectra.

 

Mark



#4 philipdehazya

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Posted 31 July 2020 - 08:45 AM

Very interesting indeed. Although the spectra is of the entire comet, do you think that the majority of the spectra is actually the nucleus, rather than the coma? That's where most of the light is coming from, no?



#5 mwr

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Posted 31 July 2020 - 11:10 AM

Wow. Very interesting. What do think is causing the Na peak in the just the center image?

Hi Dave,

 

Robin has given some remarks on this topic just recently: https://www.cloudyni...ine/?p=10355706


Edited by mwr, 31 July 2020 - 11:41 AM.

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#6 mwr

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Posted 31 July 2020 - 11:40 AM

Very interesting indeed. Although the spectra is of the entire comet, do you think that the majority of the spectra is actually the nucleus, rather than the coma? That's where most of the light is coming from, no?

Because I have used slitless spectroscopy not the entire comet but  only the bright, star-like  coma yielded an analyzable spectrum. The raw spectrum illustrates this nicely:

 

Comet_NEOWISE_SA.jpg

 

I think most of the light comes, indeed, from the huge, dusty atmosphere of the coma that reflects the sunlight and is the source of the emission lines of the spectra. The coma is far larger than the nucleus it surrounds (image taken from Donahue et al. The Cosmic Perspective):

 

coma_2.jpg


Edited by mwr, 31 July 2020 - 11:52 AM.


#7 robin_astro

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Posted 31 July 2020 - 12:24 PM

Here is a high resolution sky subtracted spectrum image of the Sodium D line region from 2020-07-20  The inset shows the orientation of the slit (the black line), roughly in the direction of the sodium and ion tails.   

 

20200720_F3_NEOWISE_raw_skysub_incguider.jpg

 

Conditions were poor so it is rather noisy but it shows the Na D lines persisting in the coma and extending out into the tail, though reduced in intensity compared to the previous spectrum on 2020-07-10.

https://www.cloudyni...lution-spectrum

 

(Unfortunately I have not been able to get any further spectra)

 

Cheers

Robin


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#8 mwr

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Posted 02 August 2020 - 12:38 AM

The sequence shows the evolution of the coma-spectra of NEOWISE that were obtained with the SA-100 as objective grating (Fuji X-A1; Canon FD 200 mm). 

To reveal the changes in the spectra in between the different points in time  I have applied a division as indicated below:

 

neowise_evolv.jpg

 

The position of the comet was computed using the 3D Solar System Simulator (https://theskylive.c...7-14&h=20&m=13).

 

Do the detected changes make sense in an astrophysical context?




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