|This image was made by combining two narrow-band|
(single-color) observations--oxygen and hydrogen spectral lines.
This is a picture of the Kronberger planetary nebula, recently found in the Digitized Sky Survey by an amateur astronomer named Matthias Kronberger. Nebulae, by the way, are the things to discover if you want something named after you or after your first pet, because if you discover anything else, it's going to be named after a year or a set of coordinates.
What are planetary nebulae?
When a regular-sized, main sequence star is at the end of its life, it can no longer sustain hydrostatic equilibrium, which means that the pressures of its gravity and its fusion cease to be equal, and the star dispenses with its outer layers. A cloud of gas expands from the star, and the star--still at the center of this gas--ionizes it, causing it to glow (like a soccerball jellyfish).
What questions do astronomers have about these nebulae?
- How does the presence of a second star in the system influence the evolution of the nebula?
- How do the presences of planets in the system influence the evolution of the nebula?
- Can planetary nebulae even form without a second star to assist in ionization?
- What are the effects of the redistribution of heavy-element material into the interstellar medium? (Stars, at the ends of their lives, fuse more than just hydrogen-hydrogen, so when they shed their outer layers, they're also shedding things like carbon).