Also known as MyCn18, the above picture, taken with the Wide Field and Planetary Camera 2 aboard NASA’s Hubble Space Telescope, is composed from three separate images that focus on the ionized nitrogen (red), hydrogen (green), and ionized oxygen (blue). The Nebula is a tenuous cloud of gas formed by a Sun-like star undergoing ‘death tremors’ at the end of its life. The star had difficulty in getting enough fuel to keep up its nuclear furnace, and has now shed off some of its surface material in two directions. A close examination reveals several forces at work to create this beautiful cosmic object. At the centre is a dense stellar object, which emits a high-energy solar wind and has a massive heavy-element core responsible for an extreme magnetic field. The flattened rings are caused by particles being trapped in complex magnetic fields and emitting light as their energy levels shift from an elevated to a static state.
The Engraved Hourglass Nebula is a young planetary nebula situated in the southern constellation Musca, about 8,000 light-years away from Earth. Annie Jump Cannon and Margaret W. Mayall during their work on the Henry Draper Catalogue discovered it, and designated it simply as a small faint planetary nebula. On January 18, 1996, Raghvendra Sahai and John Trauger of the Jet Propulsion Laboratory photographed the hourglass shape of the nebula.
Hubble also revealed other features in MyCn 18 that are new and unexpected. For example, there is a pair of intersecting elliptical rings in the central region that appear to be the rims of a smaller hourglass. There are the intricate patterns of the etchings on the hourglass walls. The arc-like etchings could be the remnants of discrete shells ejected from the star when it was younger, or could result from the action of a narrow beam of matter impinging on the hourglass walls. An unseen companion star and accompanying gravitational effects may well be necessary in order to explain the structure of MyCn 18.
The central core of the Nebula, sometimes referred to as the “Eye of God,” is a hot star (110,000 K) that lies clearly off center. There are many possible explanations for describing this structure. The Ball-of-Light Particle Model describes what is happening like this:
- The central star is indicated by the arrow “B;”
- The core of this star is a ball-of-light;
- The star is either: being closely orbited by another ball-of-light indicated by “C” or was orbited by an object such as a planet or star, and “C” was recently ejected from the core;
- Due to the precessing orbit-like rings of material evident in the area indicated by “A,” it is more likely that “C” is orbiting “B;”
- The orbiting ball-of-light is inducing massive electromagnetic waves on the core of the central star.
Credits: Encyclopedia of Science, ESA, Hubble, NASA, Wikipedia.