RA: 19h 42m Dec: +50 32
Mag: 6.0, 6.2 Sep: 39.1″ PA: 134°
Distance: 70 ly
Spectral type: G1 , G1
RA: 21h 07m Dec: +38° 45′
Mag: 5.3, 6.1 Sep: 31.1″ PA: 151°
Distance: 70 ly
Spectral type: K5 , K7
Had fun for a couple hours this morning using the two 50s – the F4.1 “Little Rascal” and the F12 Tasco – to track down a palindrome pair of stars in Cygnus – 16 Cygni and 61 Cygni. They are very similar – as are the two scopes – and yet quite different.
There’s only two-tenths of a magnitude difference between the closely matched 6th magnitude stars that make up 16 Cygni. In the scope they remind me of Albireo without the color – that is, about the same separation – but significantly dimmer. In fact, at this brightness 50mm loses some of its appeal. Of course it helps if you clean the dew off the lens and I’m not sure when the dew got on there, but I didn’t notice the problem until much later when I was viewing M11. Still, the pair have a fascination and those using larger scopes may know them simply because they are very close to the Blinking Planetary – which I could not see with the 50mm.
Actually, 16 Cygni is a triple star system about 70 light years from us and with a planet believed to be orbiting the “B” component. The A component evidently has a close companion you can’t see. So here’s the real fascination for me: In the 1960s – and I don’t know for how many years thereafter – I learned that astronomers assumed there were no planets around double stars because the system would be too unstable. Since more than half the stars are doubles, this cut the chances of finding extra-terrestrials at least by half. Yet here we have a triple star system with a planet and while it’s orbit is eccentric, it apparently is stable. (Or maybe not – do we know? ) On the site usually maintained by Jim Kaler there’s this note: “From 16 Cygni-B’s planet system (and no one knows if there are any “earths”), the somewhat brighter component, 16 Cygni-A, would shine with the brilliance of our full Moon.” Well – fun to contemplate!
Dropping to the east in the same constellation – 61 Cygni is the famous speed demon and the first star whose distance was measured using parallax. That was done in 1838 by Freidrich Bessel, so viewing it comes with a significant piece of astronomical history. The distance is about 11 light years and just that closeness to us would make it appear to speed along against the background stars, but it simply is moving faster – about five times as fast as our Sun moves according to Kaler, my favorite source on all things stellar. Kaler says this suggest that 61 Cygni is an interloper – as he put it, this implies “that 61 Cyg is not a member of the thin disk of our Galaxy, but is merely a visitor to the neighborhood.” Hmmm. . . a runaway from a globular? Or maybe a dwarf galaxy we swallowed recently???
It’s also an easy double about the same brightness as 16 Cygni and similar separation. Even the 50mm Little Rascal at 10X can split these stars, as well as Omicron1 Cygni, a nice triple – especially when the skies are as steady as they were this morning. I tried the 10X50 binoculars – mounted on a p-mount – on Omicron1 and found I could split it, though the third component was difficult.
Looking at these stars really made me appreciate the light throughput issue when you start upping the magnification. At 46X I was looking at a quite dim M11 – it looked more like a nebula with a sprinkling of star dust – except, of course, for it’s single bright star – the leader of the “wild ducks.” I highly recommend this touring at different objective diameters, though. Light is a dimension and you really do get different perspectives as you switch back and forth, much as you do with magnification. I’m also convinced there’s an ideal framing – not only in terms of field of view, but also in terms of brightness – for any given object, but of course what’s ideal for me may not be ideal for someone else. It’s simply an aesthetic judgment.
Now – it will be interesting to see if the longer focal length – possibly better quality – and slightly more light gathering area of the 60mm Unitron does better. It’s due to arrive today as the clouds roll in. But I may get a shot at testing it on these same stars Friday morning. Hey, the fun never stops!