Derby and District Astronomical Society

Double Stars

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Peter Branson produced the following image of the 'double double' Epsilon Lyrae on the 25th June 2017. In Peter's own words:

"One of the 'Chairman's Challenges' at the end of the society year was to find Epsilon Lyrae and see if anyone could split the stars into their four components - the quartet is know as 'the double double'. I thought I'd try and photograph the two stars Epsilon Lyrae 1 and 2 to see if they could be split by stacking and processing a number of separate exposures. I couldn't do it. Then I had the idea of taking a video of the stars which resulted in many more images of very short exposure - something like a 30second video at an average of 30+ frames per second. The best 250 frames could then be stacked and processed. The result was amazing!

The distance between Epsilon Lyrae 1, A and B is 2.8 arcseconds and between Epsilon Lyrae 2, C and D is 2.2 arcseconds. I calculated that the resolution of the combination of scope and camera should be about 0.32 arcsec/pixel which results in between 7-9 pixels between the A and B, and C and D pairs. So I should be able to see them!

The photograph here was the result of stacking the best 250 frames from a video captured using SharpCap controlling a ZWO ASIMC-Cool CCD camera. The camera was used in conjunction with my Celestron C9.25 SC scope mounted on an EQ5 mount. The final image has been flipped 180 degrees to place North at the top."
   Image © Peter Branson




The following image of Albireo (Beta Cygni) was produced by Peter Branson on the 25th June 2017.  In Peter's own words: "Another of the 'Chairman's Challenges' at the end of the society year was to find look at the star Albireo in Cygnus and note the different colours of the two components of this binary star. Having used a video to capture the quartet of stars in Epsilon Lyrae, I tried the technique to see what Albireo might look like. The two components are separated by 35 arcseconds and are easily split. The photograph here was the result of stacking the best 250 frames from a video captured using SharpCap controlling a ZWO ASIMC-Cool CCD camera. The camera was used in conjunction with my Celestron C9.25 SC scope mounted on an EQ5 mount. The blue colour of the hotter component is clear to see, but the light from the partner star has swamped the sensor and its yellow colour is difficult to make out. "   Image © Peter Branson



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