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Delta 1 Lyr & Delta 2 Lyr

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#1 Carbstone

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Posted 01 August 2021 - 05:12 AM

It was the American astronomer Charles B. Stephenson (1929 l 2001) who in 1959 tried to show that a group of stars that included Delta 1 Lyr and Delta 2 Lyr formed an open cluster, now better known as Delta Lyrae Cluster or Stephenson 1 (https://iopscience.i.../10.1086/127349). It was not until 1968 that this was finally confirmed (http://articles.adsabs.harvard.edu/pdf/1968ApJ...152...77E).

 

The attached sketch dates from 17/07/2021. Only a limited number of stars of the more than 65 members were visible with the 80 mm refractor. The moon (56 %), low on the horizon in the south-west will also have influenced the lesser visibility.

 

Delta 1 Lyr or 11 Lyr
AB: 5.5/9.9 175.3" 20°
The A component of Delta 1 Lyr, has a blue-white hue, the B component is white.

 

Delta 2 Lyr or 12 Lyr
AB: 4.3/11.2 86.3" 349°
AD: 4.46/8.47 193.1 210°
The A component of Delta 2 Lyr is light orange, the D component is white. The B component was not to be found at the presumed location, searched for using the Meade astrometric eyepiece.

 

The position angles of both doubles, AB & AD, differ +/- 190° and therefore 11 Lyr AB and 12 Lyr AD are oriented +/- parallel to each other but in opposite directions.

 

Dirk

 

 

Attached Thumbnails

  • Stephenson Tisselt 17 07 2021.jpg

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#2 VanJan

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Posted 01 August 2021 - 05:59 AM

Great sketch and comprehensive report! waytogo.gif

 

I was able to discern the B star of Delta 2 with my 90mm refractor at 180x, but not fully resolve it into its individual components.

 

Cheers!


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#3 Carbstone

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Posted 02 August 2021 - 10:34 AM

Thanks.

I will try again, next clear night using the 80mm/480mm, max 120x.

 

Dirk



#4 c2m2t

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Posted 05 August 2021 - 05:33 PM

Hi Dirk!

Very informative post and a wonderful sketch!! Lines up very nicely with my image. Wonderful detail given the 80mm scope...a bit wider field than my image. I have attached 2 images...one with notation, the other without to better appreciate the field. A couple of additional systems have been identified for those with larger optics.

 

Cheers, Chris.

Attached Thumbnails

  • H VI 3-7217-pt-ns-ID-Notes.jpg
  • H VI 3-7217-pt-ns-ID.jpg

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#5 Spile

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Posted 06 August 2021 - 03:21 PM

I also enjoy the Double Doubles double in this part of the sky, STF2470 and STF2474


Edited by Spile, 06 August 2021 - 03:21 PM.

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#6 ssmith

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Posted 07 August 2021 - 01:01 PM

Here is my photo of Delta 1 & 2 that goes a bit deeper showing the cluster better.

 

Delta Lyrae 120mm 7-3-17.jpg


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#7 c2m2t

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Posted 07 August 2021 - 01:12 PM

Hi Steve!

Great image! The depth is at least mag 16.0...the "C" component of ELS 7 is visible in your image.

 

Cheers, Chris.



#8 Carbstone

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Posted 08 August 2021 - 02:30 AM

Hi Chris, Steve,

 

Thanks for the pictures.

The position of the stars on the sketches should be better.

 

Thanks,

Dirk



#9 Organic Astrochemist

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Posted 18 August 2021 - 10:37 PM

Thanks to everyone who contributed to this thread. 

 

Last night I just stumbled across delta1 and delta2 Lyrae and thought they would be good targets for my extremely simple spectroscopy setup.

 

No science here, but it is easy enough to understand why delta1 Lyrae (SIMBAD gives B2V), which emits mostly in the near UV and delta2 Lyrae (SIMBAD gives M4II), which emits mostly in the near IR, form such a nice color contrast.

delta1 Lyrae.png

 

delta2 Lyrae.png

 

Apparently stars of the Stephenson 1 cluster, some other clusters and even some field stars are likely all part of a much larger "Stephenson 1" complex. See here: https://arxiv.org/abs/1909.04612

 

I think this is an interesting example of the benefit of observing optical doubles, beyond their esthetic value, as compared to only observing physical pairs.


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#10 Carbstone

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Posted 23 September 2021 - 12:56 PM

Thanks everyone for the reactions. 

Only today did I notice the reactions. 

Nice to figure out that the drawings don't deviate too far from reality.

 

Dirk




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