Epsilon Pegasi
Encyclopedia
Epsilon Pegasi (ε Peg, ε Pegasi) is the brightest star
in the constellation
Pegasus
. It has the traditional name Enif. The name "Enif" is derived from the Arabic
word for nose, due to its position as the muzzle of Pegasus.
In Chinese
, , meaning Rooftop
(asterism), refers to an asterism consisting of ε Pegasi, α Aquarii and θ Peg
. Consequently, ε Pegasi itself is known as
It is fairly average for an orange supergiant
star, well into the later stages of its stellar evolution
and as such may be considered a dying star. Enif probably only has a few million years left to go, although it is unknown whether it will explode in a supernova
or die off as a rare neon-oxygen white dwarf
, due to its mass straddling the dividing line between stars destined to explode or not. Enif has been observed to brighten radically upon a few occasions, giving rise to the theory that it (and possibly other supergiants) erupt in massive flares
that dwarf those of our own Sun
. It is a type LC slow irregular variable
star that varies from +0.7 to +3.5 in magnitude
.
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Pegasus
Pegasus (constellation)
Pegasus is a constellation in the northern sky, named after the winged horse Pegasus in Greek mythology. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations.-Stars:...
. It has the traditional name Enif. The name "Enif" is derived from the Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
word for nose, due to its position as the muzzle of Pegasus.
In Chinese
Chinese language
The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...
, , meaning Rooftop
Rooftop (Chinese constellation)
The Rooftop mansion is one of the Twenty-eight mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise.- Asterisms :...
(asterism), refers to an asterism consisting of ε Pegasi, α Aquarii and θ Peg
Theta Pegasi
Theta Pegasi is a star in the constellation Pegasus. It has the traditional name Baham .In Chinese, , meaning Rooftop, refers to an asterism consisting of θ Pegasi, α Aquarii and ε Pegasi. Consequently, θ Pegasi itself is known as Theta Pegasi is of spectral class A2 and has apparent magnitude...
. Consequently, ε Pegasi itself is known as
It is fairly average for an orange supergiant
Supergiant
Supergiants are among the most massive stars. They occupy the top region of the Hertzsprung-Russell diagram. In the Yerkes spectral classification, supergiants are class Ia or Ib . They typically have bolometric absolute magnitudes between -5 and -12...
star, well into the later stages of its stellar evolution
Stellar evolution
Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years to trillions of years .Stellar evolution is not studied by observing the life of a single...
and as such may be considered a dying star. Enif probably only has a few million years left to go, although it is unknown whether it will explode in 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...
or die off as a rare neon-oxygen white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
, due to its mass straddling the dividing line between stars destined to explode or not. Enif has been observed to brighten radically upon a few occasions, giving rise to the theory that it (and possibly other supergiants) erupt in massive flares
Solar flare
A solar flare is a sudden brightening observed over the Sun surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy . The flare ejects clouds of electrons, ions, and atoms through the corona into space. These clouds typically reach Earth a day...
that dwarf those of our own Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. It is a type LC slow irregular variable
Slow irregular variable
A slow irregular variable is a variable star that exhibit no or very poorly defined periodicity in their slowly changing light emissions. Most of them are late spectral types K and M, S stars or carbon stars...
star that varies from +0.7 to +3.5 in magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
.
See also
- Epsilon Pegasi in fiction