Astronomers using ESO’s Very Large Telescope (VLT) have captured a beautiful image of a planetary nebula called the Skull Nebula.
This image, taken by the FORS 2 instrument on ESO’s Very Large Telescope shows the Skull Nebula, a planetary nebula 1,671 light-years away in the constellation of Cetus. Image credit: ESO.
Also known as NGC 246 or Caldwell 56, the Skull Nebula is located 1,671 light-years away in the southern constellation of Cetus.
Discovered on November 27, 1785 by the German-born British astronomer, the nebula is approximately 6 light-years across.
The Skull Nebula formed when a Sun-like star expelled its outer layers in its old age, leaving behind its naked core — a white dwarf named HIP 3678 — one of two stars that can be seen at the very center of the nebula.
Even though the Skull Nebula has been known for centuries, only in 2014 did astronomers discover that HIP 3678 and its companion are concealing a third star situated at the heart of the nebula.
This star, which is not visible in the new VLT image, is a dim red dwarf that sits close to HIP 3678 at the a distance of about 500 AU.
The red and white dwarf stars orbit each other as a pair, and the outer star orbits the two dwarfs at a distance of around 1,900 AU.
Collectively, these three stars establish the Skull Nebula as the first known planetary nebula with a hierarchical triple stellar system at its center.
The new VLT image of the nebula intentionally captures light emitted in some narrow ranges of wavelengths — those associated with hydrogen and oxygen gas.
Observations of light emitted by particular elements help reveal a wealth of information about an object’s chemical and structural compositions.
The new image highlights where the nebula is rich or poor in hydrogen (shown in red) and oxygen (depicted in light blue).
