- Object: Planetary nebula
- Constellation: Sagittarius
- Right ascension: 19h 43m 57.8s
- Declination: −14° 9′ 11.9″
- Apparent size: 22″ x 15″
- Apparent magnitude: 10
- Distance: 6,000 light years
- Designations: Little Gem Nebula, NGC 6818, PK 25-17.1, HD 186282, GCRV 12096, BD-14 5523
Little Gem Nebula: General Facts
The Little Gem Nebula was given the designations PK 25-17.1, HD 186282, GCRV 12096 and BD-14 5523. It was designated NGC 6818 in the New General Catalogue.
This nebula has an apparent magnitude of 10 and a 15th magnitude central star.
What does the Little Gem Look Like?
The rich glow of the cloud in the Little Gem is just over half a light-year across — humongous compared to its tiny central star. This is usually created when stars like the Sun are near end of life and they send their outer layers into space to create glowing clouds of gas.
The Little Gem shows knotty filament-like structures and distinct layers of material, with a bright and enclosed central bubble surrounded by a larger, more diffuse cloud.
Planetary nebula often have complex shapes because the ejection of this mass is uneven. It is thought the elongated shape of NGC 6818 is because the stellar wind from the central star propels the outflowing material. As this stellar wind moves through the slower-moving cloud, it creates particularly bright spots in the bubble’s outer layers.
The Hubble Space telescope imaged this nebula back in 1997 with its Wide Field Planetary Camera 2, using a mix of filters that highlighted emission from ionized oxygen and hydrogen. Since then, many photos have been taken of it and given a different view of the nebula.
- The Little Gem Nebula was discovered by the British astronomer William Herschel in 1787.
- ESA/Hubble & NASA, Acknowledgement: Judy Schmidt-https://www.nasa.gov/sites/default/files/styles /full_width_feature/public/thumbnails/image/hubble_friday_08072015.jpg