Discovered in 1867 by a pair of French astronomers named Charles Wolf and Georges Rayet, Wolf-Rayet stars have evolved rapidly over just a few hundred million years and now they are reaping the consequences of their cosmic haste.
Apart from their immense size, the most distinguishing traits of these stars are the winds of heat and radiation that they expel as a result of the fusion of unstable core elements. These expelled elements, which produce a great amount of luminosity, will one day be responsible for the creation of entirely new generations of star systems.
"Understanding how Wolf-Rayet stars evolve is a critical link in the chain of events that ultimately led to life," says Dr. Debra Wallace of NASA's Goddard Space Flight Center.
Astrophysicist Paul Sutter outlines the basic mechanics of these "cranky" stars in his "Ask a Spaceman" video series:
There aren't many of these stars known to us in the universe due to their unusually epic size. As Sutter writes for Space.com, this is because "a) there's just fewer of them to start with, because it's hard to get big balls of gas in the first place, and b) massive stars don't live long, so if we take a snapshot of the universe, we're more likely to see the smaller, long-lived stellar denizens than their big-boned cousins."
Despite their rare status, they remain one of the most curious and beautiful celestial objects in the universe. Here are just a few of the most visually arresting Wolf-Rayet stars that Hubble has photographed over the years:
Spiral Planetary Nebula (NGC 5189)
This planetary nebula was discovered by James Dunlop in 1826, though it was only decades later that a rare low-mas WR star was found within it.
Found in the southern constellation of Carina, WR 31a is characterized by its ever-expanding bubble-like gas shell.
Little Ghost Nebula (NGC 6369)
According to NASA's Astronomy Picture of the Day, the Little Ghost Nebula is located 2,000 light-years away and "offers a glimpse of the fate of our sun, which should produce its own pretty planetary nebula only about 5 billion years from now."
Engraved Hourglass Nebula (MyCn 18)
Located 8,000 light-years away from Earth in the southern constellation of Musca, the Engraved Hourglass Nebula is the subject of one of the most intriguing images captured by the Hubble Space Telescope.
NGC 7026 is nestled 6,000 light-years away from Earth in the northern constellation of Cygnus.