M57 | NGC 6720
The Ring Nebula (also referred to as Messier 57 or NGC 6720) is a planetary nebula in the Lyra constellation.
The nebula is the remnant of a star that shed its outer gaseous envelope about 20,000 years ago. The gas envelope is expanding at a speed of 19 km/s and currently has an apparent diameter of about 118 arc seconds, which means an absolute diameter of about 1.3 light years at a distance of 2300 light years. In the telescope, the nebula appears ring-shaped, which is why it is often referred to as the Ring Nebula in the Lyre. In fact, the visible shell of gas resembles a torus. At the center of the nebula is a white dwarf star with a surface temperature of about 70,000 °C and an apparent magnitude of 15.8.
This nebula was discovered by the French astronomer Charles Messier while searching for comets in late January 1779. Messier's report of his independent discovery of Comet Bode reached fellow French astronomer Antoine Darquier de Pellepoix two weeks later, who then independently rediscovered the nebula while following the comet. Darquier later reported that it was "...as large as Jupiter and resembles a planet which is fading" (which may have contributed to the use of the persistent "planetary nebula" terminology). It would be entered into Messier's catalogue as the 57th object. Messier and German-born astronomer William Herschel speculated that the nebula was formed by multiple faint stars that were unresolvable with his telescope.
In 1800, German Count Friedrich von Hahn announced that he had discovered the faint central star at the heart of the nebula a few years earlier. He also noted that the interior of the ring had undergone changes, and said he could no longer find the central star. In 1864, English amateur astronomer William Huggins examined the spectra of multiple nebulae, discovering that some of these objects, including M57, displayed the spectra of bright emission lines characteristic of fluorescing glowing gases. Huggins concluded that most planetary nebulae were not composed of unresolved stars, as had been previously suspected, but were nebulosities. The nebula was first photographed by the Hungarian astronomer Eugene von Gothard in 1886.
Above Infos with thanks from wikipedia
Right ascension 18h 53m 35.079s
Declination +33° 01′ 45.03″
Distance 2567±115 ly (787±35 pc)
Apparent magnitude 8.8
Apparent dimensions 230" x 230"
Radius 1.3 ly
Absolute magnitude −0.2 +0.7−1.8
- Teleskop: Skywatcher 200 PDS, 1,000 mm, 5", f/5
- Mount: Skywatcher AZ-EQ5 GT
- Camera: ZWO ASI 183MC
- Software: Sharpcap Pro 4.0.8973.0
- Total time: 860s | Frames: 215 | 4 s | Gain: 250
- Cutout: 1200 x 802 pixel of Data: 5496 x 3672 pixel
- Darks: none
- Flats: none
- Optic: APM-Barlow 1,5x: 1.500 mm | f/7,5
- Filter: none
- Date: 2022-08-02 | Time: 23:34 UTC | SENSOR: 25.3 °C
Image META information
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