Credit: ESA/Hubble & NASA
Acknowledgements: Luca Limatola, Budeanu Cosmin Mirel
This
NASA/ESA Hubble Space Telescope image shows the planetary nebula NGC
2452, located in the southern constellation of Puppis. The blue haze
across the frame is what remains of a star like our sun after it has
depleted all its fuel. When this happens, the core of the star becomes
unstable and releases huge numbers of incredibly energetic particles
that blow the star's atmosphere away into space.
At the center of this blue cloud lies what remains of the nebula's
progenitor star. This cool, dim, and extremely dense star is actually a
pulsating white dwarf, meaning that its brightness varies over time as
gravity causes waves that pulse throughout the small star's body.
NGC 2452 was discovered by Sir John Herschel in 1847. He initially
defined it as "an object whose nature I cannot make out. It is certainly
not a star, nor a close double star [...] I should call it an oblong
planetary nebula." To early observers like Herschel with their smaller
telescopes, planetary nebulae resembled gaseous planets, and so were
named accordingly. The name has stuck, although modern telescopes like
Hubble have made it clear that these objects are not planets at all, but
the outer layers of dying stars being thrown off into space.
