European Space Agency
An image of NGC 6818, known as Little Gem Nebula. ESA/Hubble & NASA. Acknowledgement: by Judy Schmidt
This colorful bubble is a planetary nebula called NGC 6818, also known as the Little Gem Nebula. It is located in the constellation of Sagittarius (The Archer), roughly 6,000 light-years away from us. The rich glow of the cloud is just over half a light-year across – humongous compared to its tiny central star – but still a little gem on a cosmic scale.
When stars like the sun enter “retirement,” they shed their outer layers into space to create glowing clouds of gas called planetary nebulae. This ejection of mass is uneven, and planetary nebulae can have very complex shapes.
NGC 6818 shows knotty filament-like structures and distinct layers of material, with a bright and enclosed central bubble surrounded by a larger, more diffuse cloud.
Scientists believe that the stellar wind from the central star propels the outflowing material, sculpting the elongated shape of NGC 6818. As this fast wind smashes through the slower-moving cloud, it creates particularly bright blowouts at the bubble’s outer layers.
Hubble previously imaged this nebula in 1997 with its Wide Field Planetary Camera 2, using a mix of filters that highlighted emission from ionized oxygen and hydrogen. This image, while from the same camera, uses different filters to reveal a different view of the nebula.
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Disclaimer: Re-published content may have been edited for length and clarity. The appearance of hyperlinks does not constitute endorsement by the Department of Defense. For other than authorized activities, such as, military exchanges and Morale, Welfare and Recreation sites, the Department of Defense does not exercise any editorial control over the information you may find at these locations. Such links are provided consistent with the stated purpose of this DoD website.
from Armed with Science http://ift.tt/1KtHPqC
European Space Agency
An image of NGC 6818, known as Little Gem Nebula. ESA/Hubble & NASA. Acknowledgement: by Judy Schmidt
This colorful bubble is a planetary nebula called NGC 6818, also known as the Little Gem Nebula. It is located in the constellation of Sagittarius (The Archer), roughly 6,000 light-years away from us. The rich glow of the cloud is just over half a light-year across – humongous compared to its tiny central star – but still a little gem on a cosmic scale.
When stars like the sun enter “retirement,” they shed their outer layers into space to create glowing clouds of gas called planetary nebulae. This ejection of mass is uneven, and planetary nebulae can have very complex shapes.
NGC 6818 shows knotty filament-like structures and distinct layers of material, with a bright and enclosed central bubble surrounded by a larger, more diffuse cloud.
Scientists believe that the stellar wind from the central star propels the outflowing material, sculpting the elongated shape of NGC 6818. As this fast wind smashes through the slower-moving cloud, it creates particularly bright blowouts at the bubble’s outer layers.
Hubble previously imaged this nebula in 1997 with its Wide Field Planetary Camera 2, using a mix of filters that highlighted emission from ionized oxygen and hydrogen. This image, while from the same camera, uses different filters to reveal a different view of the nebula.
Follow us on Facebook and Twitter for military science and technology updates!
———-
Disclaimer: Re-published content may have been edited for length and clarity. The appearance of hyperlinks does not constitute endorsement by the Department of Defense. For other than authorized activities, such as, military exchanges and Morale, Welfare and Recreation sites, the Department of Defense does not exercise any editorial control over the information you may find at these locations. Such links are provided consistent with the stated purpose of this DoD website.
from Armed with Science http://ift.tt/1KtHPqC
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