Astronomy ... and You, 2020
credit: Cygnus and Lyra, public domain image. Author Sydney Hall 1825.
"There was the door to which I found no key;
There was the Veil through which I could not see"
-The Rubayyat of Omar Khayyam
Constellation Cygnus, one of the brightest and largest in our skies, has long been recognized as a bird. As the name implies, it is now known as The Swan. Its five main stars are also recognized as a crucifix: the Northern Cross. The Swan appears to be flying south along the Milky Way. The alpha star Deneb is at the abbreviated tail, and a long neck extends south to the beta star Alberio.
credit: Summer Triangle. Author Martin Mark
licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
The constellation offers objects of great interest for observers with small telescopes, binoculars, or even keen eyes. Deneb is one of the three bright lights making up the Summer Triangle which has been high overhead since June. The others [seen above] are Altair, the head of Aquila the Eagle, and Vega, in the smallish geometric Lyra. By late November the trio rotates to the west, and the Northern Cross orients more vertically over the horizon.
The head of the Swan, Alberio, is overwhelmingly regarded as the finest double star of all. Its components are a deep yellow, described as topaz, and a blue some call sapphire, but I see it as a green/blue mix. Astronomers say that color differences stand out when stars are close, but the Alberio pair have a wide enough separation to be seen easily in a small scope. I have seen both beauties in 10 x 30 binos held steadily against a porch post.
The Swan has a star (61 Cyg) that would be utterly average except for one anomally. 61 has been tagged as the “Flying Star” because of its proper motion. Previously, we discussed proper motion with regard to the Big Dipper. In 10,000 years or so, it will lose its shape because of the slow drift of some stars moving in a different direction from others. The Flying Star makes those drifters look like slackers. The Burnham guide shows two photos of 61 Cyg, taken 32 years apart. The change in its position relative to neighbors is jaw-dropping. Where is it going? And why? See Projects below.
Lastly, we show some images of the feathery adornments on the Swan – the wispy nebulas. One resembles the North American continent, and nearby a Pelican, and a third, a Veil.
Picture credits. Top: The Veil. Author Ken Crawford; left: North Ameicanr nebula. Author Ole Nielsen,
licensed under the Creative Commons Attribution-Share Alike 2.5 Generic license; right: Pelican nebula.
Author Miodrag Sekulic, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
… and You
1. 61 Cygnus, the Flying Star, has a large sideways motion owing in part to its nearness to us. It scoots to the northeast at a clip of 5" (seconds of arc) per year. Estimate how much sky it would cover in a lifetime using the first link below. Compared to Barnard's Star, it is slower but easily observed due to its brightness.
2. Look into the first candidate suspected of harboring a black hole. An X-ray source kown as Cygnus X-1.
3. Now you see it .... Not to be confused with X-1 is the variable star Chi Cygnus (Chi written as X in the Greek alphabet.) Find out the range of magnitudes that this one star exhibits regularly. At its brightest, how does it compare with the brightest of stars? How often can we expect its maximums? At minimum the star hides among the myriad other dim stars of this region of the Milky Way.
Next Month: Pegasus to the Rescue
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