Planetary nebulae come in all shapes and sizes. This one is spherical.

Planetary nebulae
are the most common type of nebula in most galaxies. They are expanding shells around young white dwarfs, the remains of intermediate-mass stars in which nuclear fusion has ceased.

The smallest of the three types of nebulae, with most having a diameter of only around 0.01 parsecs, planetary nebulae can be found in all types of galaxies, usually being the dominant type of nebula in sheer numbers.

Distribution Edit

Planetary nebulae occur in all types of galaxies. In spiral galaxies, they appear in all regions, though they are especially common in the halo and core. In elliptical and irregular galaxies, they are also common, though they seem to be much more common in the central regions.

Characteristics Edit

Appearance Edit

Most planetary nebulae have a spherical or flattened shape, though some can have an irregular shape. Since nebulae in the current version of Space Engine use preset models, the diversity of shapes and colours these nebulae can appear in is limited.

Truly spherical planetary nebulae can come in either orange, green or blue/yellow colour. The colour of the other types of nebulae depends purely on their preset textures.

Diameter Edit

Most planetary nebulae will be very small, being only around 0.01 parsecs in diameter.

Luminosity Edit

This type of nebula will usually have a luminosity between 10 and 20 solar luminosities. Although this is faint compared to diffuse nebulae, planetary nebulae are still not the faintest type of nebula since supernova remnants will usually have luminosity below 5 solar luminosities and will be much larger at the same time.

Central star Edit

Planetary nebulae will always contain a central system with at least one white dwarf. If the white dwarf is solitary, it will sometimes have a large number of comets around itself. This system will often contain at least one binary partner(most often a brown dwarf) which might contain a planetary system, in rare cases even harbouring life.