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#1 brucepiano

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Posted 25 August 2013 - 11:36 AM

What is the designation and magnitude for the double star in the center of Messier 11?

#2 azure1961p

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Posted 25 August 2013 - 11:48 AM

WDS18511-0617
8.0-12.4v, 5.8" @191PA

Per Sky Safari

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#3 PJ Anway

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Posted 25 August 2013 - 04:53 PM

J(Jonckheere) 107AB

8.47 - 11.34 mag., 6.39" sep, 192° p.a.

#4 azure1961p

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Posted 25 August 2013 - 06:27 PM

PJ,

Your information is spot on. I update my Sky Safsri when they ask for it but itd be nice if it truly did that. I'm guessing my info is outdated and possibly wrong on magnitude.

Thanks.

Pete

#5 brucepiano

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Posted 25 August 2013 - 09:09 PM

I don't have Sky Safari, but I could download it for my IPOD touch. Was the center star of the cluster visible, and you just clicked on it to get the listing?

#6 WRAK

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Posted 26 August 2013 - 06:57 AM

Did you resolve J107 with your 10" scope?
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#7 azure1961p

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Posted 26 August 2013 - 07:07 AM

Yes. Had to zoom in a but though.

Here's how it looks:


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#8 WRAK

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Posted 26 August 2013 - 07:53 AM

See now that it is acually a multiple star with maybe 4 or more components.
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#9 blb

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Posted 26 August 2013 - 08:14 AM

See now that it is acually a multiple star with maybe 4 or more components.

When does a multiple star become a small cluster and no longer a multiple star? Are not all open clusters gravitionaly bound together?
:question:

#10 azure1961p

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Posted 26 August 2013 - 09:01 AM

I thought the qualifier for a double or multiple system was that all orbited about each other in defined cyclical paths. An open cluster while gravitationally bound to its members and changes shape over the eons, has no such cyclical orbital behavior. Not to say some members of an OC don't orbit each other as doubles and multiple systems abound in these things. But the cluster as a whole isn't orbiting around its seperate members.

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#11 GlennLeDrew

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Posted 26 August 2013 - 10:10 AM

Double and multiple stars do exist in clusters. In older and more populated clusters, hard binaries are more likely to exist than soft binaries, as their small orbit and hence strong binding makes them more resistant to the effects of tides and encounters with other cluster members. And so there are many more spectroscopic binaries in clusters than there are optically resolved ones.

#12 brucepiano

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Posted 26 August 2013 - 10:43 AM

If you are referring to the central star in the cluster- yes, but barely. A few nights ago was the best view of M11 I have had. It was also on the meridian. I could barely split it with the Hyperion 13mm, and Siebert Optics 5.9 Star Splitter. The latter was a little better. But I could see a double.

I also use the Orion Lights out cape, which improves the view about 10-15% and blocks out light. The cape is especially good for doubles, and open clusters.

In a bright open cluster, such as the Double Cluster, or M11, the effect of blocking out light is quite noticeable.

#13 WRAK

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Posted 26 August 2013 - 04:38 PM

I found the following entries in the WDS catalog:
Name - m1 - - m2 - -sep -pos
J107AB 08,62 11,34 06,3 192
J107AC 08,62 11,89 09,9 147
J107CD 11,89 12,20 03,6 197
J107AE 08,62 12,50 15,8 093
J107EF 12,50 12,70 03,4 327
Sounds nice. M11 is one of my favorite open clusters and J107 seems just another reason to visit it again.
But what did you now see exactly? All members of this multiple should be easy to resolve with 10" aperture.
Wilfried

#14 azure1961p

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Posted 26 August 2013 - 07:42 PM

Here's a clise in shot- doubles appear here and there but no designations. Field of view in the screen shot for scale.


Pete

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#15 GlennLeDrew

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Posted 27 August 2013 - 12:40 AM

I would not be surprised if one or more of the resolved doubles in this cluster (and others) are just line-of-sight pairings of cluster singletons.

#16 brucepiano

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Posted 27 August 2013 - 06:17 AM

I am not getting all these stars in my version- educational. The double NE of the center with a bluish star in your pic does not show up in my version.
Where are the boundaries of the cluster? Is S Scuti in the cluster? I may want to upgrade.

#17 brucepiano

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Posted 27 August 2013 - 06:26 AM

I could barely resolve one component- the star just SE of HD 174512.

#18 azure1961p

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Posted 27 August 2013 - 06:42 AM

The boundaries are beyond the field of view in the screenshot as it was zoomed in very tight.

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#19 blb

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Posted 27 August 2013 - 09:44 AM

Where are the boundaries of the cluster? Is S Scuti in the cluster? I may want to upgrade.

I noticed in the upper right hand corner of the above screenshot that the field-of-view was only 4.2'x6.6' in size. Most sources list the size of M11 as being about 14' in diameter, so this screenshot is only a small portion of the center of the cluster. To see the edge of the cluster you would need to zoom out for a screen size that is larger than the cluster.

#20 brucepiano

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Posted 27 August 2013 - 10:14 AM

I also found that when I downloaded 3plus, I could see many more stars in M11. It looked similar to the view in my scope.
However, it was more difficult to identify the central star found in the basic version. The double I thought I was looking may not be a double and is a Tycho star 5126-4051-1. I flipped my screen vertically( disabling rotation) and I found that I couldn't find the central star in the cluster.

But I was able to locate the central star using the HD designation.

The 3plus app is much more comprehensive than the basic for doubles.






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