This file is in the public domain because it was created by NASA and ESA. NASA Hubble material (and ESA Hubble material prior to 2009) is copyright-free and may be freely used as in the public domain without fee, on the condition that only NASA, STScI, and/or ESA is credited as the source of the material. This license does not apply if ESA material created after 2008 or source material from other organizations is in use.
This Wide Field and Planetary Camera 2image of NGC 6818 shows two distinct layers of gas (with dust): a spherical outer region and a brighter, vase-shaped interior 'bubble.' Astronomers believe that a fast wind - material propelled by radiation from the hot central star - is creating the inner elongated shape. The central star of the planetary nebula appears as a tiny blue dot. The material in the wind is traveling so fast that it smashes through older, slower-moving stellar debris, causing a 'blowout' at both ends of the bubble (lower right and upper left).
来源
ESA/Hubble
提供者
Robert Rubin (NASA/ESA Ames Research Center), Reginald Dufour and Matt Browning (Rice University), Patrick Harrington (University of Maryland), and NASA/ESA
简短标题
Planetary nebula NGC 6818
使用条款
Creative Commons Attribution 4.0 International License