A star at the center of this tie-dye apparition is collapsing, a process scientists have watched and measured for decades. In 2020 astronomers overcame the 3,000 to 6,500 light-years separating us from this celestial beauty, named NGC 2899, for the clearest picture of it yet.
Though the phenomenon is called a planetary nebula, the term is a misnomer. These cosmic clouds appear when a star burns through the hydrogen at its core. The outer layers of the star separate while the center falls inward, transforming into a white dwarf. As it caves, the core generates ultraviolet radiation and six-million six-million-mile-per-hour winds. Clouds of gas, laden with elements ejected by the star through its lifetime, glow under the heat of the radiation and are shoved outward by the winds. In the image of NGC 2899, oxygen (blue) is surrounded by hydrogen (pink).
The expelled gas is normally fairly round, so early astronomers in the 1700s assumed the spectacle came from a planet—hence the phenomenon’s name. Discovered in 1835 by English astronomer John Herschel in the constellation Vela, NGC 2899 looks like a butterfly because it is made of two stars. Scientists think that one of them is collapsing andthat the second is interfering with the normal gas expulsion pattern, creating the symmetrical form of only 10 to 20 percent of planetary nebulae. The spectacular sight will eventually show up closer to home: our own sun should reach this phase of its life span in several billion years.
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