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Cosmic Challenge: A Trio of Binaries

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#1 PhilH

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Posted 01 September 2021 - 05:20 AM

How close can two stars appear and still be resolvable as two? The single most important factor that influences the result is a telescope's aperture. All other things being equal, the larger the aperture, the finer the level of detail resolved. Of the many observational experiments that have been conducted to determine the resolution limits of telescopes, the two most often cited are the Rayleigh Criterion and the Dawes Limit.

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#2 Stellar1

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Posted 01 September 2021 - 07:39 AM

This is really interesting though I doubt I can tackle any one of these with a 4” frac but, you can bet I’ll try.


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#3 Sasa

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Posted 02 September 2021 - 06:49 AM

This is really interesting though I doubt I can tackle any one of these with a 4” frac but, you can bet I’ll try.

Sure you have quite a chance.

 

I was able to split STF3057 back in 2012 in 80mm refractor (AS80/1200). STF3062 was only elongated star in the same telescope.

 

Over time I tried many pairs. Out of recent ones, 16 Vul (0.8", 5.8+6.2) comes to my mind. Here I was able to see the elongation already in 82mm refractor, it was still only elongated star in 142mm Newton, while 200mm Newton showed a hint of darker separation between the two components.

 

And for unequal pair, I remember zeta Her (nowadays around 1.4", 3.0+5.4). I was observing it with my friend. While there was no trace of the secondary in my friends Newton 200/1200mm, both of us could see the component in my 82/1670mm refractor. Later my friend told me that he was able to see the component in 200mm Newton as well during another night.

 

A little bit more easier is nearby 52 Her (2.1", 4.8+8.5). Here I have positive observations in 82mm refractor, 142mm Newton and my friends 200mm Newton.


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#4 Astrojensen

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Posted 02 September 2021 - 01:01 PM

Hi Phil

 

Where do you have the data on STT 12 (Lambda Cas) from? According to Stelledoppie, the current separation is just 0.1"...!  

 

 

Clear skies!

Thomas, Denmark


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#5 Sasa

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Posted 02 September 2021 - 05:06 PM

I checked STF3057 and STF3062 tonight with my 82mm refractor. Transparency was not the best, the air was very humid and the telescope was covered by the thick layer of condensed water. This was probably the reason why I failed to see the second component of STF3057 (I had few short hints of secondary at PA~290deg but too short to be sure that I saw it). I had more luck with STF3062, here I could see at 278x nice clear tail attached to the Airy disc of main component at PA~0deg. Sometimes it looked like a separated star, may be because of slight color contrast. The main component looked slightly yellowish while the tail was slightly bluer. For fun, I checked lambda Cas as well. Not surprisingly, I could not see even the elongation, however the star looked definitely strange at 330x, I had a feeling that the image of the star could not be focused properly.

 

I had to use hair dryer at this point to get rid of the dew on the lens and after short peek at Saturn I made this sketch of Jupiter

 

Jupiter_20210902_2045UT.png


Edited by Sasa, 02 September 2021 - 05:08 PM.

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#6 sgottlieb

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Posted 04 September 2021 - 01:25 AM

Hi Phil

 

Where do you have the data on STT 12 (Lambda Cas) from? According to Stelledoppie, the current separation is just 0.1"...!  

 

 

Clear skies!

Thomas, Denmark

The 0.3" separation appears to come from Phil's 2011 book.  As you mentioned, Stelledoppie shows the 2021 separation at 0.10", which makes it quite a challenge!


Edited by sgottlieb, 04 September 2021 - 01:29 AM.

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#7 mdiastro

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Posted 04 September 2021 - 09:42 AM

Hello Phil. I'll give this a go with my 82mm Questar and see what happens.



#8 Migwan

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Posted 07 September 2021 - 10:42 AM

Hi Phil
 
Where do you have the data on STT 12 (Lambda Cas) from? According to Stelledoppie, the current separation is just 0.1"...!  
 
 
Clear skies!
Thomas, Denmark


I just want to thank you for this info. I'm feeling better already. I've made it down to .46" with my C11 and tried for this bugger twice now. Probably invested 1.5 hours it. I do love a challenge, but...
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#9 PhilH

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Posted 07 September 2021 - 12:40 PM

I've heard from a few people about the separation of Lambda Cas.  I pulled it from my book from 11 years ago.  Still looking for my notes, so once I run it down, I'll post an update here.


Edited by PhilH, 07 September 2021 - 12:40 PM.


#10 sgottlieb

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Posted 07 September 2021 - 04:06 PM

You can see the separations over a 30 year period and the apparent orbital plot of Lambda Cas on Stelledoppie.

 

The pair has been slowly decreasing for quite awhile and we're currently pretty close to the minimum separation (under 0.09"), which will be in a couple of years.

 

I remember being very excited to resolve it back in 1980 using a C-8.  At the time I believe the separation was about 0.5" and it appeared as two tangent airy discs using 444x.


Edited by sgottlieb, 07 September 2021 - 05:07 PM.

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#11 Special Ed

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Posted 10 September 2021 - 10:19 PM

I tried the challenge tonight using a C8 which I just cleaned inside and out and collimated.  The seeing was not good--I gauged it at 4/10 Pickering but the transparency was excellent.  I had more luck with STF 3057 than with STF 3062.  I could see the secondary starting at 167x and  even better at 200 and 250x.  It was very small and dim compared to the primary and appeared to be at ~PA 300 degrees.

 

I stepped up from 167x all the way to 299x trying to split STF 3062 but only got a hint of elongation.  I think the seeing was the limiting factor.

 

Since I couldn't get anywhere with 3062 I didn't even try lambda Cas.



#12 Sasa

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Posted 14 September 2021 - 03:57 PM

I checked STF3057 tonight with my 82mm refractor under much more favorable conditions - no dew, good transparency and good seeing. As expect, I had no problem to see the companion in 8mm eyepiece (power 210x). It was very faint star visible with strong concentration for most of the time at PA~320 deg. Mu rough estimate of its distance from the main component was about 1.8 times the radius of the first Airy ring, which should be around 4'' (if I did the math correctly).

 

BTW, Jupiter was also excellent in these conditions

 

Jupiter_20210914_2000UT.png




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