A list of all 147 named nebulae of the night sky that can be found by eye, binoculars, or telescope (denoted by magnitude). Nebulae are interstellar gas and dust clouds that emit (emission nebulae), reflect (reflection nebulae), or absorb (dark nebulae) light of different wavelengths. Many large nebulae can have emission, reflection, and dark components, such as the large Orion nebula. Supernova remnants can also be thought of as a type of emission nebulae, as explained at the end.
- Name / Magnitude
⚛ EMISSION NEBULAE
An emission nebula (EN) is an ionized gas cloud that emits light of various wavelengths. The most common source of ionization are high-energy photons emitted from a nearby hot star. Planetary nebulae, HII regions, and Herbig-Haro objects are different types of emission nebulae.
A planetary nebula (PN) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives before they become a white dwarf. This is the fate of our sun. Planetary nebulae generate many of the heavier elements in the periodic table as a result of the high temperatures from the expulsion.
An HII region is a type of emission nebula consisting of an area within a giant hydrogen gas cloud that has collapsed under gravity to create a star-forming region. These newborn stars then ionize and light up gas and dust around them.
A Herbig-Haro (HH) object is a type of emission nebula formed when narrow jets of partially ionized gas ejected by newborn stars collide with nearby clouds of gas and dust at high speed. HH objects are commonly found in star-forming (HII) regions.
⚟ REFLECTION NEBULAE
A reflection nebula (RN) is a cloud of interstellar gas and dust that reflects the light of nearby stars. The energy from the nearby stars is insufficient to ionize the gas in the cloud to create an emission nebula, but is enough to to make the dust visible.
A protoplanetary nebula (PPN) is a type of reflection nebula that consists of gas ejected from red giant stars late in their life. This gas reflects the light of the red giant. PPNs form before the planetary nebula phase, where the gas is ionized to form an emission nebula.
☁ DARK NEBULAE
A dark nebula (DN), also called an absorption nebula, is an interstellar dust cloud dense enough to obscure the visible wavelengths of light from objects behind it, such as background stars and emission or reflection nebulae. Small dark nebulae are called Bok globules. Many different types of molecules have been detected on the tiny dust grains in dark nebulae.
❇ SUPERNOVA REMNANTS
A supernova remnant (SNR) results from the explosion of a star in a supernova, and consists of ejected material expanding from the explosion and interstellar material it sweeps up in the shock wave. A Type II supernova results from a high-mass star ceasing to generate fusion at it's core, collapsing inward under gravity, then exploding outward, leaving a neutron star or black hole. A Type Ia supernova results from a white dwarf sucking material from a binary companion star over time until it reaches critical mass and explodes. Supernovae generate most of the heavier elements in the periodic table as a result of the intense pressures and temperatures from the explosion.