Elephant trunks
Encyclopedia
Elephant Trunks are formations of interstellar matter found in space. They are located in O type and B type stars, which can form an expanding bubble known as an H II region. Elephant trunks look like massive pillars or columns of gas, but they come in various shapes, lengths, and colors. Astronomers study elephant trunks because of their unique formation process and use to 2D and 3D simulations to try to understand how this phenomenon occurs. Elephant trunks do not have a useful function, but their unusual structure makes them fascinating to study.
s. The gas does not ionizes evenly throughout the cloud, therefore there are randomly generated clumps of denser gas scattered throughout the cloud. These dense clumps are called evaporating gaseous globules (EGGs), and they are the starting point for the formation of an elephant trunk. The pillar shape is formed when the EGGs act as a shield for the gases that lay behind them from the stellar winds. Stellar wind
s are a continuous flow of gas that is ejected from the stars and causes the lighter and less dense gas to erode away. The EGGs and the column of gas "downwind" from them is the basic formation of an elephant trunk.
. NASA was able to produce a picture of this formation by compiling multiple images together taken from the Hubble Space Telescope
. It is 7,000 light years away and located in the Eagle Nebula
, which is a cluster of stars that are the same age in the constellation Serpens. There are multiple elephant trunks in the Pillars of Creation and one of the columns is around seven light years long. Astronomers have discovered that the Pillars of Creation no longer exist because they were destroyed 6,000 years ago by the shock waves of a stellar explosion called a supernova
.
is an example of an unusual shape that an elephant trunk can form. It has a double helix structure instead of the normal straight column. The double helix is caused by the presence of magnetic fields and electric currents lined up along the trunks axis. This makes the filaments of the columns wavy instead of straight like they are in normal trunks. These filaments wrap around each other rather than line up next to each other which forms the twisted structure.
Formation
O type and B type stars are a classification of stars that strongly emit ultraviolet (UV) radiation. The UV radiation causes the surrounding cloud of hydrogen gas to ionize, forming H II regionH II region
An H II region is a large, low-density cloud of partially ionized gas in which star formation has recently taken place. The short-lived, blue stars forged in these regions emit copious amounts of ultraviolet light, ionizing the surrounding gas...
s. The gas does not ionizes evenly throughout the cloud, therefore there are randomly generated clumps of denser gas scattered throughout the cloud. These dense clumps are called evaporating gaseous globules (EGGs), and they are the starting point for the formation of an elephant trunk. The pillar shape is formed when the EGGs act as a shield for the gases that lay behind them from the stellar winds. Stellar wind
Stellar wind
A stellar wind is a flow of neutral or charged gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric.Different types of stars have...
s are a continuous flow of gas that is ejected from the stars and causes the lighter and less dense gas to erode away. The EGGs and the column of gas "downwind" from them is the basic formation of an elephant trunk.
Structure
Elephant trunks form on the outer wall of the H II region cloud. Astronomers can only study the structure of the surface of the trunks because the opaqueness of the gas obscures the internal core. The length of the columns are measured in light years, which is the distance that it takes light to travel in one year. Astronomers can calculate the densities and temperatures of the EGGs and the trunks by using infrared, millimeter, and radio observations. They have determined that elephant trunks have cold cores (20K) surrounded by warm gas (60K) with an outer hot shell (250-320K).Pillars of Creation
The most famous example of an elephant trunk is the Pillars of CreationPillars of Creation
Pillars of Creation refers to a photograph taken by the Hubble Telescope of elephant trunks of interstellar gas and dust in the Eagle Nebula, some 7,000 light years from Earth. It was taken April 1, 1995 and was named one of the top ten photographs from the Hubble by Space.com...
. NASA was able to produce a picture of this formation by compiling multiple images together taken from the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
. It is 7,000 light years away and located in the Eagle Nebula
Eagle Nebula
The Eagle Nebula is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745-46. Its name derives from its shape which is resemblant of an eagle...
, which is a cluster of stars that are the same age in the constellation Serpens. There are multiple elephant trunks in the Pillars of Creation and one of the columns is around seven light years long. Astronomers have discovered that the Pillars of Creation no longer exist because they were destroyed 6,000 years ago by the shock waves of a stellar explosion called a supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
.
Rosette Nebula
The Rosette NebulaRosette Nebula
The Rosette Nebula is a large, circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy...
is an example of an unusual shape that an elephant trunk can form. It has a double helix structure instead of the normal straight column. The double helix is caused by the presence of magnetic fields and electric currents lined up along the trunks axis. This makes the filaments of the columns wavy instead of straight like they are in normal trunks. These filaments wrap around each other rather than line up next to each other which forms the twisted structure.