Cygnus
| Cygnus | |
|---|---|
| |
| Observational Data | |
| Right ascension | 20.62 |
| Declination | +42.03o |
| Nearby constellations | Cepheus Draco Lyra Vulpecula Pegasus Lacerta |
| Area | 804 sq. deg. |
| Number of stars | 84 Bayer/Flamsteed stars |
| Main stars | 9 |
| Brightest star | Deneb 1.25m |
| Nearest star to Earth | 61 Cygni (11.4 ly) |
| Known planets | 6 |
| Messier objects | 2 |
| Ancient symbol | The swan |
Cygnus is a constellation located in the northern celestial hemisphere. The constellation was one of the 48 constellations recorded by Ptolemy in his Almagest or Great Book, and is one of the 88 modern constellations. The name Cygnus itself is the Latin form of the original Greek word, Κύκνος (Kuknos), meaning swan.[1] The constellation also features the Northern Cross, a well-known asterism of stars. The brightest star of the constellation, Deneb, represents both the head of the Northern Cross and the tail of the swan.
Mythological Background
There are several stories in Greek mythology that involve the constellation Cygnus. One myth involved Zeus and the goddess Nemesis. Nemesis sought to escape from Zeus by disguising herself as various animals. According tot he legend, when she changed herself into a goose, Zeus transformed himself into a beautiful swan and won her over. The constellation was then formed to celebrate the exquisite swan. Another version has Zeus becoming the swan in order to court the queen of Sparta, Leda.[2]
Another Greek legend has Cygnus as one of two birds (the other being the eagle Aquila, also a constellation), that were hunted by Hercules, but managed to escape. It is believed that the two birds, along with Lyra (the vulture) were the Stymphalian Birds, whom Hercules were to slay as the sixth of the twelve labors.[3]
In Chinese mythology, the constellation is the once-a-year magpie bridge known as 鹊桥 (Que Qiao) from the story of the princess and the cowherd.
Stars and Other Features
The binary star Albireo (Beta Cygni) represent the head of the swan. The tail is where the brightest star of the constellation, Deneb, is located. Deneb is also the tip of the Northern Cross and the upper-left corner of the Summer Triangle. The dim binary star 61 Cygni also lies within the constellation and is the closet star within it, only some 11.4 light years away, and is famous for being the first star to be measured using parallax.
Cygnus is also the location of several notable deep sky objects, including numerous diffuse and planetary nebulae, and [open star cluster|open star clusters]]. The Fireworks Galaxy (NGC 6946) is also located here, known as the most active supernovae galaxy known. Another galaxy is Cygnus A, one of the strongest astronomical radio source known in the cosmos. Cygnus X-1 is another astronomical feature within the constellation and is famous for not only being one of the greatest known sources of x-rays, but the first discovered example of a black hole.[3]
Named Stars
- Deneb - Alpha Cygni (α Cyg)
- Albireo - Beta Cygni (β Cyg)
- Sadr - Gamma Cygni (γ Cyg)
- Ruc - Delta Cygni (δ Cyg)
- Gienah - Epsilon Cygni (ε Cyg)