To celebrate 25 years since the completion of the International Gemini Observatory, students in Chile voted for the Gemini South telescope to image the Butterfly Nebula, which is also known as NGC 6302, the Bug Nebula, or Caldwell 69.
This image, captured by the Gemini South telescope, shows the planetary nebula NGC 6302. Image credit: International Gemini Observatory / NOIRLab / NSF / AURA / J. Miller & M. Rodriguez, International Gemini Observatory & NSF’s NOIRLab / T.A. Rector, University of Alaska Anchorage & NSF’s NOIRLab / M. Zamani, NSF’s NOIRLab.
NGC 6302 is a planetary nebula located 2,417 light-years away in the constellation of Scorpius.
“A planetary nebula is a type of emission nebula consisting of a massive star near the end of its life that is expelling material, surrounded by an expanding, glowing shell of ionized gas,” astronomers from the International Gemini Observatory said in a statement.
“Typically, these mesmerizing structures have a planet-like round shape, which is why they were named ‘planetary nebulae’ by the early astronomers who observed them through their telescopes.”
Sources report various dates of NGC 630’s discovery, but credit typically goes to a 1907 study by the American astronomer Edward E. Barnard, though the Scottish astronomer James Dunlop may have discovered it in 1826.
The nebula shows extreme bipolar, complex morphology, the presence of very high excitation gas, high molecular mass, and crystalline silicate dust.
Its butterfly shape stretches for more than two light-years, which is about half the distance from the Sun to Proxima Centauri.
“The glowing ‘wings’ of the Butterfly Nebula appear to be bursting out of the interstellar medium in the new image captured by the Gemini South telescope,” the astronomers said.
“This picturesque object was chosen as a target for the 8.1-m telescope by students in Chile as part of the Gemini First Light Anniversary Image Contest.”
“The contest engaged students in the host locations of the Gemini telescopes to celebrate the legacy that the International Gemini Observatory has built since its completion, marked by Gemini South’s First Light in November 2000.”
In 2009, astronomers used the Wide Field Camera 3 on board the NASA/ESA Hubble Space Telescope to identify NGC 6302’s central star as a white dwarf that expelled its outer layers over 2,000 years ago and is now around two-thirds the mass of our Sun.
It is one of the hottest stars known, with a surface temperature in excess of 250,000 degrees Celsius (450,000 degrees Fahrenheit), implying the star from which it formed must have been very large.
Further studies of NGC 6302 have revealed a dramatic formation history.
Before becoming a white dwarf, the star was a red giant with a diameter about 1,000 times that of the Sun.
The massive star shed its outer layers of gas, which traveled outward from the equator at a relatively slow speed to form the dark, doughnut-shaped band still visible around the star.
Other gas was expelled perpendicular to the band, which restricted the outflows and created the bipolar structure seen today.
As the star continued evolving, it unleashed a powerful gust of stellar wind that tore through the ‘wings’ at more than 3 million km per hour (1.8 million miles per hour).
Interactions between slow- and fast-moving gas further texturized the ‘wings’ into expansive landscapes of cloudy ridges and pillars.
Now, as a white dwarf, the star is emitting intense radiation that is heating the ‘wings’ of NGC 6302 to more than 20,000 degrees Celsius (around 35,000 degrees Fahrenheit) and causing the gas to glow.
“The rich red in the image traces areas of energized hydrogen gas, while the stark blue traces areas of energized oxygen gas,” the researchers said.
“This material, in addition to the other elements scientists have found in NGC 6302, such as nitrogen, sulfur, and iron, will go on to help form the next generation of stars and planets.”
