Elephant’s Trunk Nebula
The Elephant’s Trunk Nebula brings up a vision of the circus with its winding arrangements of stars, gas, and cosmic dust clouds. This emission nebula exists in the star cluster IC 1396 in the far-off Cepheus Constellation. It brightens the dark sky almost 3,000 light-years from Earth. The cosmic elephant’s trunk is more than 20 light-years long.
Why Is It Called Elephant’s Trunk Nebula?
The Elephant’s Trunk Nebula is known as IC 1396A or VdB 142. It gets its name from its massive and vast gas and cosmic dust pillars. This elephant trunk term applies to monstrous formations like those found in the Pillars of Creation in the Eagle Nebula.
New generations of stars form when radiation and stellar winds from young stars collide with cooler-temperature gas clouds. Scientists believe this phenomenon regularly occurs in the Elephant Trunk Nebula.
How Do Astronomical Elephant Trunks Form?
B-type and O-type stars emit ultraviolet (UV) radiation that causes surrounding clouds of hydrogen gas to ionize and form HII regions.
However, clumps and clusters of denser gas form within the cloud when the gas doesn’t ionize evenly. So, the elephant trunks form inside these dense groupings called evaporating gaseous globules (EGGs.)
The continuous gas flow of stellar winds from the central star erodes any lighter gasses and dust within the clouds. That allows for forming a pillar shape (elephant trunk) when the EGGs act as stellar windshields for the gasses behind them. In addition, the material behind the EGGs compresses into clumps where new stars form (HII regions.)
Elephants’ trunks form on the HII region’s outer walls, where their internal cores become obscured by opaque gasses. That means astronomers need infrared and x-ray light wavelengths to calculate EGG and trunk temperatures and densities.
Scientists know that elephant trunk structures have cold cores surrounded by warm gas. Finally, a hot outer shell completes the trunk structure.
Where Is the Elephant’s Trunk Nebula Located?
Find the Elephant Trunk Nebula in the constellation Cepheus. Most observers can see it in mid-Northern latitudes and above. That means it doesn’t dip below the horizon so that you can see this cosmic display throughout the night, particularly on cold, clear nights during November.
You’ll note that Cepheus appears to swing around the northern celestial pole, anchored near the upper right of the North Star, Polaris.
The nebula resides in the larger ionized gas area called IC 1396.
Look for the bright star, Alderamin, and then cast your gaze southwest to find IC 1396. Within it, you’ll find the Elephant Trunk Nebula.
What Type of Nebula Is Elephant’s Trunk?
The Elephant Trunk Nebula is an emission nebula. Light from the massive star toward the east, HD 206267, ionizes and illuminates the nebula’s dense cloud surface.
Additionally, the elephant’s trunk has more than 250 young stars identified within and around it. This star formation region has very young stars (about 100,000 years old) and older stars (about 2 million years old.)
The Major Types of Nebula
Nebulae are gas and cosmic dust clouds mainly composed of hydrogen and helium. They are vast star nurseries and sometimes star cemeteries, too.
The three major types of nebulae are emission, reflection, and dark. However, you may also read about planetary nebula and supernova remnants (like in the Lupus Constellation.)
Emission nebulae are clouds of ionized gas that emit their own light at optical wavelengths. They form when nearby stars’ intense ultraviolet radiation energizes the gas clouds by stripping electrons from their hydrogen atoms. Then those energized electrons recombine with atoms to change from a higher to a lower energy state. Finally, their energy shines in the form of light, thus causing glowing gas within the nebula.
Dust clouds that primarily reflect a nearby star’s light are called reflection nebulae. Their central stars don’t have enough power to ionize the nebula’s gas, so instead, their light causes their gas and dust to glow. Think of it like a street light shining through and in the fog.
Dark or absorption nebulae are cold black patches in interstellar space. Their irregular shapes block light from any stars lying beyond them. Approximately half of all cosmic material resides within these dark formations. They are so dense that they hold millions of hydrogen molecules per cubic centimeter.
Planetary nebulae form during the deaths of low to medium-mass stars. While they have nothing to do with planets, they get their names because they look like planets.
Stars with a mass at least five times the Sun’s can explode (in the final phase of their lifecycle) into a supernova. They spew contents into space, creating supernova remnants. When these remnants are a few thousand years or younger, the gas inside the nebula mostly comes from the exploded star.
How Big Is Elephant’s Trunk Nebula?
The elephant Trunk winds through IC 1396, a large emission nebula and young star complex on its own. While the elephant trunk spans 20 light-years, this more prominent host spans 100 light-years.
The image below went through digital processing to remove the stars. As a result, it is easier to view the bright ridges swept back by the EGGs. These ridges outline cool-temperature interstellar gas and dust pockets.
Notice the dark finger or tendril-shaped clouds. These HII regions hide protostars within themselves and also contain star formation materials.
Another exciting part of this image is “The Caravan.” These dark objects towards the bottom right get their name from appearing to march toward the Elephant’s Trunk. Imagine a caravan of people and package-laden camels trekking through the desert.
This particularly stunning view of the Elephant’s Trunk Nebula gives you an idea of its immensity. The image spans a one-degree-wide field of view, which is approximately the size of 2 full moons.
Interesting Dark Sky Objects Near the Elephant’s Trunk Nebula
The region’s brightest star is Mu Cephei (μ Cep), a red supergiant. It is one of the furthest stars visible without binoculars at an approximate distance of 2,840 light-years away. That’s because this variable star has an average apparent magnitude of 4.08 and a radius of 1,260 to 1,650 times that of the Sun. It is one of the biggest stars ever discovered, so look for it on a dark, cloudless night. Additionally, its striking red color gives Mu Cephei its secondary name of Hershcel’s Garnet Star.
Other notable deep-sky objects near the Elephant’s Trunk Nebula include the Bubble Nebula in Cassiopeia and the Fish, Wizard, and Seahorse Nebulas within Cepheus.
The Elephant’s Trunk Nebula resides in the Cepheus Constellation, about 3,000 light-years from Earth. This vast gas and cosmic dust pillar is approximately 20,000 light-years across within the more significant star cluster, IC 1396.
View it in the Northern hemisphere from any dark sky area throughout the night. You can see it during the summer months. However, cooler months like November with crisp, clear skies make for the best viewing opportunities.