Look for the celestial swan
By Vernon Whetstone
One of the grandest constellations in the northern night sky is Cygnus, the Swan, also known as the Northern Cross.
From the third magnitude double-star Albireo at the beak, to the brilliant alpha star, Deneb, at the tail along with the outstretched wings, Cygnus makes a grand sight.
Plus, the bright starry band of the Milky Way runs the length of the constellation providing a great background for observing.
Deneb, the leftmost star of the Summer Triangle, is from the Arabic for “Tail.” Other stars have references to the tail position. Deneb Kaitos, the tail star of Cetus, the Whale, Deneb Algedi, the tail star of Capricornus, the Sea Goat, and Denebola, the tail star of Leo the Lion.
The best time to look for the celestial swan this week is after 9:30 pm MT looking just above the northeast horizon. The length of the swan’s body points north/south and the wings extend east/west.
Binoculars will not show the double nature of Albireo, but even a small telescope will separate the pair and show their magnificent color contrast, one is a brilliant yellowish/amber and the other is a soft, pale blue.
Although the pair are close in distance (377 and 386 light-years from the Sun), it is not known if they are a true double orbiting a common center. One source says that if they are, their orbital period would be about 100,000 years.
Deneb, the tail star, is a blue/white super-giant star about 2,600 light-years from Earth, and is the 19th brightest star in the night sky. It is estimated to be 100 to 200 times the size of our Sun and up to 196,000 times brighter.
There are a couple of celestial goodies nested in the swan. The first is the grand super nova remnant, the Veil Nebula. It is one of my grandson’s favorites because he loves to say, “Super nova remnant.”
At magnitude seven it could be possible, from a very dark-sky location, to catch a glimpse of the two halves of what is left of a star that blew itself apart an estimated five to eight thousand years ago. But the overall surface brightness is so spread out that it would be difficult.
The two halves, or arcs of the shell, are all that is left. It is best to use an Oxygen III filter with even a small telescope to view the celestial wonder. The rightmost half of the arc is centered on the star 52-Cigni.
Look just to the southern side of the lower wing-tip.
The second object is commonly called the North American nebula for it obvious resemblance to the North American continent, especially with the coast of Mexico extending to the Florida peninsula. Again, an Oxygen III filter would work best.
The giant cloud of gas and dust is located a little more than three degrees below and slightly left of Deneb.
SKYWATCH: Third-quarter moon tomorrow night, Thursday, June 19. In the early morning hours of Tuesday, June 24, a deliciously slender crescent moon will be just below and right of the bright planet Venus which is itself just to the lower right of the Pleiades star cluster. Look just above the eastern horizon no later than an hour before sunrise.
NEXT WEEK: More astronomical blathering.