Some Double Stars in Ursa Minor

So as was discussed in my last post, on the 28th February 2014 I decided to try and tackle a few double stars within the constellation of Ursa Minor. I looked at six different stars and succeeded in splitting four of them into some of their component stars. I basically managed to split Struve 1840, Struve 1841, Pi-1 Ursae Minoris & h2682. In the image below I have highlighted where in the constellations these stars are located.

In regards to the two failures, the first was 5 Ursae Minoris and whilst I saw the 4.3 magnitude primary burning brightly I just seemed unable to locate the dimmer 9.9 magnitude component even though it should be possible for my telescope. I will probably tackle it again in the future from a darker site as there was a fair bit of light pollution from my neighbours' homes by the time I tackled this star.

The other star I failed to split was Hu908 which at a separation of only 1.5 arc-seconds was always going to be a struggle for me to manage with my telescope. Bumping the magnification to try and split it resulted in my view being far too unstable so I gave up on this one very quickly. I suspect to have any chance I am going to need a super stable night and possibly a better mount if not another telescope.

And now that we have dealt with my failures of the night let us move on to the successes!

Struve 1840 (HIP 70041 / SAO 16342) 
RA : 14 19 54.86   Dec: +67 46 56.9
Magnitudes: 7.0, 10.1
Separation: 27.3”
Position Angle: 222°

Struve 1841 (HIP 70141 / SAO 16352)
RA : 14 21 07.78   Dec: +67 48 10.4
Magnitudes: 7.3, 11.1
Separation: 34.9”
Position Angle: 265°

Struve 1840 and 1841 are two stars I had tried to target previously but the weather and an annoying security light had caused me issues. So these were the first doubles I targeted, the main reason was that I thought it would be nice to see both of them in the same field of view which I managed quite easily. However, even without the neighbours security lights and a lack of rain I still struggled to make out the two dimmer companion stars and had to employ averted vision techniques to enable me to catch the odd sight of them. Both these doubles just came out as white which seems to be a common comment around the internet so I don't think I was missing anything spectacular on the colour front. To be honest both Struve 1840 and 1841 are very similar looking to each with only the only obvious difference being the minor variation in position angles.

Pi-1 Ursae Minoris / Struve 1972 (HIP 75809 & 75829 / SAO 2556 & 2558) 
RA : 15 29 11.19   Dec: +80 26 55.0
Magnitudes: 6.6, 7.3, 11.4
Separation: 31.4”, 152.3”
Position Angle: 79°, 105°

This is probably one the easiest stars I had to split this evening, mainly because the A & B components had a decent separation and were quite bright. I did struggle on for about 5-10 minutes to try and see the 11.4 C component but I just couldn't catch a glimpse of it which was a shame as I was hoping I might be able to see it. The nice thing about this double is that I actually saw a little bit a colour here, both stars had a faint yellow tinge which you can hopefully make out in the sketch below.

I highlighted HIP 75874 & HIP 76450 in the sketch because they actually make a nice triangle with Pi-1 UMi which helps confirm you are actually in the right location.

h2682 (HIP 66728 / SAO 7867) 
RA : 13 40 40.82   Dec: +76 50 37.6
Magnitudes: 6.7, 10.3, 9.2
Separation: 25.8”, 43.8”
Position Angle: 282°, 317°

My final successful double of the night was actual a triple star and I actually managed to make out all three components which made this my favourite of the night. It wasn't that easy as the magnitude 10.3 B component seemed determined to hide itself from me, but patience and some averted vision helped to tease it out of the darkness. The three components actually produce a nice little squashed triangle at the heart of the eyepiece and whilst I wasn't able to tease out any colours I have read reports of yellow, blue and violet being used to describe the different components. I would have loved to see some of that but it was still nice enough without the colour.

Overall, this was an incredibly successful night for me in regards to the doubles I decided to take a look at and if it wasn't for some cloud cover affecting the beginning of my night I may have managed a few more. The amazing thing is that there are still lots more doubles for me to check out in Ursa Minor alone, never mind the other constellations! They could probably keep me busy for years although I suspect many of them aren't the most exciting to look at.