· · · ·

NGC 6765

The constellation of Lyra is home to one of the best known and most distinctive planetary nebulae in the sky, the Ring Nebula between the stars Sulafat and Sheliak. The same constellation is also home to another, far less prominent planetary nebula, NGC 6765, which lies somewhat to the southeast of the Ring Nebula. NGC 6765 can be found in the sky approximately halfway between the Ring Nebula and Albireo, the star that marks the southward-pointing beak of Cygnus the Swan.

NGC 6765 lies several thousand light years from the Solar System, though its precise distance is difficult to ascertain with certainty. It is clearly more distant than the Ring Nebula (which lies some 2,300 light years from the Sun), but much closer than M56, a globular cluster in the same general direction that falls some 33,000 light years from the Sun. Most estimates place NGC 6765 at about 5,000 light years from the Solar System, but with a wide margin of error.

While the Ring Nebula has a well-defined ring shape that is visible with even a modest telescope, NGC 6765 has a much more complex structure, and is also considerably fainter. It has an apparent magnitude of +13.1 compared with the Ring's +8.8, meaning that it is more than fifty times fainter. Its form is rather indistinct, but it appears bluish in colour, with a central linear feature running through the fainter globular shape of the expanding gases around its central star. Because its distance is uncertain, so is its actual diameter in space, but it appears to be between one and two light years from side to side.