duminică, 13 februarie 2011
The ring nebula
Planetary Nebula M57 (also known as the Ring Nebula, NGC 6720 or Messier Object 57) is located in the constellation Lyra. It is among the most well known and recognizable examples of a planetary nebula. The nebula is located at 0.7 kpc(2300 light-years) from Earth and was discovered by Antoine Darquier de Pellepoix in 1779. The nebula has a visual magnitude of 8.8, and a photographic magnitude of 9.7. It is expanding at a rate of approximately 1 arcsecond per century (corresponding to 20-30 km/s). Its mass is approximately 1.2 solar mass.
M57 is illuminated by a central white dwarf of 14.7 visual magnitude. This star was discovered in 1800 by Count Friedrich von Hahn.
M57 is best seen through at least an 8-inch telescope, but even a 3-inch telescope will show the ring.
Right Ascention 18:53 Declination 33.02.
I've amde this 50X70 tempera painting of Ring Nebula when I was in highschool