IC 1396 is a large

emission nebulae An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission n ...

, a region of ionized gas, located in the constellation

Cepheus Cepheus (Ancient Greek: Κηφεύς ''Kepheús'') may refer to: In Greek mythology * Cepheus (father of Andromeda), and King of Aethiopia * Cepheus (son of Aleus), a king of Tegea, Arcadia In astronomy * Cepheus (constellation), one of the 88 m ...

about 2,400

light year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s away from Earth. IC 1396 is illuminated and ionized by a very bright, massive multiple star

HD 206267 HD 206267A is a hierarchical triple star system in the northern circumpolar constellation of Cepheus. Two of the members form a spectroscopic binary that orbit each other with a period of 3.7 days, while a third member lies further awa ...

at its center, except for dense globules that can protect themselves from the star's harsh ultraviolet rays. This hierarchical

triple star A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally called a ''sta ...

system has two members that form a

spectroscopic binary A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

that orbit each other with a period of 3.7 days, while a third member lies further away—it is unclear whether this third member is

gravitationally bound The gravitational binding energy of a system is the minimum energy which must be added to it in order for the system to cease being in a gravitationally bound state. A gravitationally bound system has a lower (''i.e.'', more negative) gravitatio ...

to the pair. The system is emitting a

stellar wind A stellar wind is a flow of gas ejected from the stellar atmosphere, 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 spheri ...

that reaches an exceptional velocity of 3,225 km/s, among the highest measured for stars of this type. Jutting from the rim of the nebula is IC 1396A, commonly called the Elephant's Trunk Nebula, a dark, dense globule with a bright, sinuous rim being illuminated by HD 206267.

References

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External links

IC 1396 in Mapped Color
17 August 2004. Russell Croman Astrophotography. Retrieved 2010-10-13 {{Portal bar, Astronomy, Stars, Outer space Dark nebulae IC objects Star-forming regions Cepheus (constellation)

1396 Year 1396 ( MCCCXCVI) was a leap year starting on Saturday of the Julian calendar. Events January–December * May 19 – Martin I succeeds his brother, John I, as King of Aragon (modern-day northeastern Spain). * July 20 &ndash ...

See also

References

Sources

External links