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Splitting Polaris? Not in Stellarium

beginner double star observing planetarium software
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#1 mr.otswons

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Posted 12 December 2019 - 01:18 AM

I have tried to understand this for many hours now. Probably should post this in the beginner's forum, as I am clearly not near any closure.

 

"Polaris is a spectroscopic binary with separation around 0.1 arcsec. so, any planetarium will show it as one star." - is the answer I got from Stellarium forum. If you zoom in as much as possible in Stellarium, well ..

 

Stelldoppie says: Sep. Now 18.4"

 

Are they talking about the same stars?

 

Here on CN people are comparing the least magnification used to split Polaris.

 

Please help, my head is splitting!

 



#2 james7ca

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Posted 12 December 2019 - 01:41 AM

Polaris is a multiple star and has more than one companion. I'm not sure how many of these are actual physical components, some may just be optical doubles. Here is a post (on Flickr) where I imaged most of the stars that are usually associated with Polaris (but not, of course, the spectroscopic components). It also has all of the information on all of the known and suspected members of this star system.

 

  https://www.flickr.c...ge/10828141654/

 

Here is a link with some more information:  https://www.cloudyni...b/#entry8450557


Edited by james7ca, 12 December 2019 - 01:44 AM.

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#3 Waddensky

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Posted 12 December 2019 - 02:01 AM

If you take a look at the Stelle Doppie page of Polaris, you'll see that all components from the WDS are listed under System Components. The pair with a separation of 18.4 seconds is the AB pair (Struve 93), the spectroscopic double is the Aa,Ab pair (WRH 39) with a separation of 0.1 seconds. There are some other pairs listed too.

https://www.stelledo...p?iddoppia=9153
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#4 Jon Isaacs

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Posted 12 December 2019 - 02:36 AM

I recommend Sky Safari if you're interested in double stars.

 

It lists the AB pair up above at 18.4" and down below it lists several other component pairs including the 0.1" spectroscopic pair. It also computes the orbits of short period binaries so you get current separations for doubles like Castor, Porrima, Sirius etc.

 

Jon


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#5 Sky Muse

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Posted 12 December 2019 - 02:36 AM

I have tried to understand this for many hours now. Probably should post this in the beginner's forum, as I am clearly not near any closure.

 

"Polaris is a spectroscopic binary with separation around 0.1 arcsec. so, any planetarium will show it as one star." - is the answer I got from Stellarium forum. If you zoom in as much as possible in Stellarium, well ..

 

Stelldoppie says: Sep. Now 18.4"

 

Are they talking about the same stars?

 

Here on CN people are comparing the least magnification used to split Polaris.

 

Please help, my head is splitting!

I just downloaded the latest version of Stellarium, and I still can't see any companion-stars for Polaris listed, mentioned or shown, and no matter how high I zoom.  If enough people complain, then maybe the authors will include them, but not within the latest version.  Personally, I'm just as livid over the omissions.


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#6 mr.otswons

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Posted 12 December 2019 - 10:15 AM

I recommend Sky Safari if you're interested in double stars.

 

It lists the AB pair up above at 18.4" and down below it lists several other component pairs including the 0.1" spectroscopic pair. It also computes the orbits of short period binaries so you get current separations for doubles like Castor, Porrima, Sirius etc.

 

Jon

I will definitely check out Sky Safari.

 

 

I just downloaded the latest version of Stellarium, and I still can't see any companion-stars for Polaris listed, mentioned or shown, and no matter how high I zoom.  If enough people complain, then maybe the authors will include them, but not within the latest version.  Personally, I'm just as livid over the omissions.

Ok, so I am not crazy! Thanks!



#7 DeWayne

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Posted 12 December 2019 - 10:24 AM

If you don't already have it, the latest edition of the Cambridge Double Star Atlas has a good description of the AaBb types of multiple star systems, which might help alleviate some of the confusion in general. Also, Wulff Heinz's double star book can be found as a free download and it provides a really deep description of it all. I find it fascinating and delightful to observe and study about these multiple star systems!

I regularly use Polaris's ninth magnitude companion as a test for optics and sky conditions...

Clear skies.
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#8 Jon Isaacs

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Posted 12 December 2019 - 10:29 AM

I will definitely check out Sky Safari.

 

 

There are three versions, one is free, the others are the Plus and Pro.

 

Only the Pro provides the additional components.  The free  and us only provide the 18.4".

 

There are Sky Safari versions for Android, iOS and Macs.

 

Jon


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#9 mr.otswons

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Posted 12 December 2019 - 06:21 PM

There are three versions, one is free, the others are the Plus and Pro.

 

Only the Pro provides the additional components.  The free  and us only provide the 18.4".

 

There are Sky Safari versions for Android, iOS and Macs.

 

Jon

Not free, at least not here in Norway, about 2$ for the simplest- and it doesnt show α umi b either. Actually neither Stellarium nor Skysafari (simplest version) shows that. Nor Kochab. Hm..

 

 

If you don't already have it, the latest edition of the Cambridge Double Star Atlas has a good description of the AaBb types of multiple star systems, which might help alleviate some of the confusion in general. Also, Wulff Heinz's double star book can be found as a free download and it provides a really deep description of it all. I find it fascinating and delightful to observe and study about these multiple star systems!

I regularly use Polaris's ninth magnitude companion as a test for optics and sky conditions...

Clear skies.

Thanks! Have downloaded the Heinz book, quite deep indeed!

 

To test optics became my general idea. If my Skymax 127 doesn't split Polaris, under good conditions, I might consider throwing it under the bus4.gif

Well, I do not have high hopes, but where I am now is supposed to be 2 Bortle, so there is a chance...

 

To sum up, I was not so wrong to be frustrated when not finding the right views in Stellarium, and now only have to really pin down what is considered Polaris companions that are achievable to see through a telescope.

As I understand it, the real companions are spectroscopic and are unavailable for amateur astronomer. And what people are calling splitting Polaris, is just visual, and not really related to Polaris by gravity.

 

Thanks for all the input and forgive my ignorance and impatience, wanting to understand everything at once.


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#10 Waddensky

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Posted 12 December 2019 - 07:18 PM

As I understand it, the real companions are spectroscopic and are unavailable for amateur astronomer. And what people are calling splitting Polaris, is just visual, and not really related to Polaris by gravity.

In this case, both Polaris B (at 18.4") and Ab (at 0.1") are gravitationally bound to Polaris A. It's a triple star system.

 

Edit: here's an interesting paper about Polaris B


Edited by Waddensky, 12 December 2019 - 07:20 PM.

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