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A globular with spiral structure?

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#1 Jef De Wit

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Posted 29 July 2012 - 04:37 AM

We had some clear nights in Belgium. I sketched some asterisms and one globular cluster.

Lord Rosse saw spiral structure in M92 (the other globular cluster in Hercules). I could dedect only one "spiral arm": a nice row of stars starting from the south side and curving to the east side.
12" @ x240, FOV +/- 20', SQM 19.2

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#2 Jef De Wit

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Posted 29 July 2012 - 04:43 AM

Of the six asterism I sketched, this one was the nicest. Poskus 1 is a small but fine asterism that looks like a fly swatter. It is situated 10' northwest from the nice double Gamma Delphinus. Both objects are a beautiful sight. Check it out!
12" @ x92, FOV +/- 40', SQM 19.0, not all field stars are sketched

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#3 curiosidad

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Posted 29 July 2012 - 05:22 AM

You are an Artist!

#4 maroubra_boy

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Posted 29 July 2012 - 06:14 AM

What a lovely quirky signature feature you've noted Jef. I love picking out these special features in globulars. Give each GC its own unique charateristics.

#5 Ed D

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Posted 29 July 2012 - 07:53 AM

Two very nicely done sketches. I also learned something new about M92. Thanks!!!

Ed D

#6 frank5817

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Posted 29 July 2012 - 11:24 AM

Jef, Very fine sketch of M92 and the fly swatter, I CAN SEE IT-COOL!

Frank :)

#7 Rutilus

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Posted 29 July 2012 - 02:10 PM

Excellent work Jef.

#8 GlennLeDrew

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Posted 29 July 2012 - 03:57 PM

To address the question posed in the title, it is of course impossible for a globular--or any cluster--to posses any kind of spiral structure. By their nature, the orbits of the member stars are randomly oriented, with the whole population very quickly well mixed. Any apparent alignments would be transitory, and certainly not coherent in the third dimension. And of course, the visual system is quite adept at picking out such alignments, as though it were a fundamental characteristic to discern organized patterns.

#9 niteskystargazer

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Posted 29 July 2012 - 04:19 PM

Jef,

Very good sketch of M-92 :).

CS,KLU,

:thanx:,

Tom

#10 JeanB

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Posted 29 July 2012 - 09:41 PM

Jef,

you are at the top of your art!!!

Jean

#11 Jef De Wit

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Posted 30 July 2012 - 11:20 AM

Thanks you guys for the nice comments.
Thanks Glenn, for the astrophysics.

#12 mike73

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Posted 31 July 2012 - 01:48 AM

Very tidy sketches Jef and I really like how you picked out the asterism in M92.
I've been reading Stephen O'Meara's Messier Objects and he does exactly the same. When you really look all globulars are very different. :)

#13 Mizar76

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Posted 01 August 2012 - 04:49 AM

Very very nice work Jef!
Compliments!!!
Stefano

#14 observing1

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Posted 01 August 2012 - 06:59 PM

I went to an astronomy tour in Arizona, and looked through a pro's telescope at M3, which is a globular. I was very convinced it looked spiral, but everyone told me globular clusters can't be spiral. I'm stumped too.

#15 Jef De Wit

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Posted 02 August 2012 - 04:36 AM

Mike & Stefano: :thanx:

@ observing1: I never looked at M3 with a big scope, but will keep it in mind for a next visite.

#16 phily

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Posted 08 August 2012 - 01:52 PM

Very interesting sketch, very nicely done. Lovely clear sky!
Phil

#17 geminijk

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Posted 11 August 2012 - 12:04 AM

Beautiful sketches! I never noticed it with M92, but M5 always sees to remind me of a spiral.

John

#18 Andrev

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Posted 11 August 2012 - 04:59 AM

Jef.

Well, you just me curious to see both now. I never remarked any spiral looking effect in M92, but for sure I'll pay more attention next time. And your second asterism is very interesting. The double star look very interesting too. I have to check that.

Thanks for sharing. Beautiful sketches.

Andre.

#19 Andrev

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Posted 11 August 2012 - 12:58 PM

Jef.

I'm trying to find the Delphinus in Sky Tools and I can't see it ??? Very strange. You said you FOV is 40' as shown on the picture ? Which range of mangitude are the stars ?

Andre.

#20 mdowns

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Posted 11 August 2012 - 03:26 PM

Jef De Wit
It took me forever to find this scetch I did 30 years ago with a 10" dob about 20 miles east of Indianapolis. Interestingly the stars in my field look very different than yours.Maybe I mislabled this one but I think I was very sensitive to yellow stars.I recall my observing buddy always saying that a star I said was bright would seem faint to him. Nonetheless I do show a curving arc of stars that might be thought of as a portion of a spiral.

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#21 Jef De Wit

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Posted 18 August 2012 - 01:58 PM

Thanks, all! I was two weeks on holiday (without internet), so sorry for the late reaction...

@ John: I never observed M5 with a big scope, but will keep it in mind.

@ Andre: Poskus 1 is small (6,5') and weak (I guess stars around mag 13-14). It is situated some 10' northwest of Gamma Del. Maybe this 30' wide photo of DSS can help.

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#22 Andrev

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Posted 28 August 2012 - 05:19 AM

Jef

I pointed M92 last saturday and I clearly saw the spiral look of this glob. Very nice one. Thanks for pointing this particularity.

Andre.

#23 rodelaet

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Posted 31 August 2012 - 12:35 AM

Speaking of spiral structure, the one object that amazed me with a spiral 'feature' was ... an open cluster! Have you ever looked at M25 with a pair of binoculars? :cool:

Clear skies,






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