Gamma Draconis
Encyclopedia
Gamma Draconis (γ Dra, γ Draconis) is a star
in the constellation
Draco
. It has the traditional name Etamin or Eltanin (Arabic: التنين At-Tinnin The great serpent), and the Flamsteed designation 33 Draconis.
This star, along with β Dra
(Rastaban), μ Dra
(Erakis), ν Dra
(Kuma) and ξ Dra
(Grumium) were Al ʽAwāïd, "the Mother Camels", which was later known as the Quinque Dromedarii..
In Chinese
, , meaning Celestial Flail
, refers to an asterism consisting of γ Draconis, ξ Draconis
, ν Draconis
, β Draconis
and ι Herculis
. Consequently, γ Draconis itself is known as
of spectral type
K5, lying 148 light years
away. Despite its Bayer designation
of "gamma," it is actually the brightest star in Draco, outshining Rastaban (Beta Draconis
) by nearly half a magnitude. In fact, the name "Rastaban" was formerly used for Eltanin, and the two terms share an Arabic
root meaning "serpent" or "dragon." Its proximity to the point directly overhead
of London
has also earned it the name "Zenith Star." As for other places, it is relatively easy to locate in the night sky. If one finds Vega, Eltanin is the red star just north of it.
In 1.5 million years, Eltanin will pass within 28 light years of Earth. At this point (assuming its current absolute magnitude does not change) it will be the brightest star in the night sky, nearly as bright as Sirius
is at present.
In 1728, while unsuccessfully attempting to measure the parallax
of this star, James Bradley
discovered the aberration of light
resulting from the movement of the Earth. Bradley's discovery proved Copernicus' theory
that the Earth revolved around the Sun.
was a United States Navy
Crater class cargo ship
named after the star.
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....
Draco
Draco (constellation)
Draco is a constellation in the far northern sky. Its name is Latin for dragon. Draco is circumpolar for many observers in the northern hemisphere...
. It has the traditional name Etamin or Eltanin (Arabic: التنين At-Tinnin The great serpent), and the Flamsteed designation 33 Draconis.
This star, along with β Dra
Beta Draconis
Beta Draconis is the third brightest star in the constellation of Draco. It has the traditional name Rastaban, which has also been used for Gamma Draconis....
(Rastaban), μ Dra
Mu Draconis
Mu Draconis is a binary star with a combined magnitude of 4.92m located approximately 85 light years from the Solar System, near the head of the constellation Draco. The component stars are nearly identical yellow-white stars in a tight orbit...
(Erakis), ν Dra
Nu Draconis
Nu Draconis is a double star in the constellation Draco. The respective components are designated ν1 Draconis and ν2 Draconis...
(Kuma) and ξ Dra
Xi Draconis
Xi Draconis is a star in the constellation Draco. It has the traditional name Grumium or Genam.This star, along with β Dra , γ Dra , μ Dra and ν Dra were Al ʽAwāïd, "the Mother Camels", which was later known as the Quinque Dromedarii.In Chinese, , meaning Celestial Flail, refers to an asterism...
(Grumium) were Al ʽAwāïd, "the Mother Camels", which was later known as the Quinque Dromedarii..
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 Celestial Flail
Purple Forbidden enclosure
The Purple Forbidden enclosure is one of the San Yuan or Three enclosures. Stars and constellations of this group lie near the north celestial pole and visible all year from temperate latitudes in the Northern Hemisphere.-Asterisms:The asterisms are :...
, refers to an asterism consisting of γ Draconis, ξ Draconis
Xi Draconis
Xi Draconis is a star in the constellation Draco. It has the traditional name Grumium or Genam.This star, along with β Dra , γ Dra , μ Dra and ν Dra were Al ʽAwāïd, "the Mother Camels", which was later known as the Quinque Dromedarii.In Chinese, , meaning Celestial Flail, refers to an asterism...
, ν Draconis
Nu Draconis
Nu Draconis is a double star in the constellation Draco. The respective components are designated ν1 Draconis and ν2 Draconis...
, β Draconis
Beta Draconis
Beta Draconis is the third brightest star in the constellation of Draco. It has the traditional name Rastaban, which has also been used for Gamma Draconis....
and ι Herculis
Iota Herculis
Iota Herculis is a fourth-magnitude star in the constellation Hercules. The luminary shares an etymological similarity with the star Rigel in the constellation of Orion, as both stars refer to one of the feet of each mythological hero.In Chinese, , meaning Celestial Flail, refers to an asterism...
. Consequently, γ Draconis itself is known as
Properties
Eltanin is an orange giantGiant star
A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...
of spectral type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
K5, lying 148 light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
away. Despite its Bayer designation
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...
of "gamma," it is actually the brightest star in Draco, outshining Rastaban (Beta Draconis
Beta Draconis
Beta Draconis is the third brightest star in the constellation of Draco. It has the traditional name Rastaban, which has also been used for Gamma Draconis....
) by nearly half a magnitude. In fact, the name "Rastaban" was formerly used for Eltanin, and the two terms share an 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...
root meaning "serpent" or "dragon." Its proximity to the point directly overhead
Zenith
The zenith is an imaginary point directly "above" a particular location, on the imaginary celestial sphere. "Above" means in the vertical direction opposite to the apparent gravitational force at that location. The opposite direction, i.e...
of London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
has also earned it the name "Zenith Star." As for other places, it is relatively easy to locate in the night sky. If one finds Vega, Eltanin is the red star just north of it.
In 1.5 million years, Eltanin will pass within 28 light years of Earth. At this point (assuming its current absolute magnitude does not change) it will be the brightest star in the night sky, nearly as bright as Sirius
Sirius
Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek: Seirios . The star has the Bayer designation Alpha Canis Majoris...
is at present.
In 1728, while unsuccessfully attempting to measure the parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...
of this star, James Bradley
James Bradley
James Bradley FRS was an English astronomer and served as Astronomer Royal from 1742, succeeding Edmund Halley. He is best known for two fundamental discoveries in astronomy, the aberration of light , and the nutation of the Earth's axis...
discovered the aberration of light
Aberration of light
The aberration of light is an astronomical phenomenon which produces an apparent motion of celestial objects about their real locations...
resulting from the movement of the Earth. Bradley's discovery proved Copernicus' theory
Heliocentrism
Heliocentrism, or heliocentricism, is the astronomical model in which the Earth and planets revolve around a stationary Sun at the center of the universe. The word comes from the Greek . Historically, heliocentrism was opposed to geocentrism, which placed the Earth at the center...
that the Earth revolved around the Sun.
Namesakes
USS Etamin (AK-93)USS Etamin (AK-93)
USS Etamin was a Crater-class cargo ship constructed for the U.S. Navy for duty in World War II, named after Etamin, the other name of Eltanin, the star in constellation Draco. She served the military in the Pacific Ocean by providing food and material until she was torpedoed and put out of service...
was a United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
Crater class cargo ship
Crater class cargo ship
Crater-class cargo ship is a category of freighter that was constructed for use by the United States Navy during World War II under Maritime Commission EC2-S-C1 type....
named after the star.
See also
- Lists of stars in the constellation Draco
- Class K Stars
- Giant starGiant starA giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...
- Gamma Draconis in fiction
External links
- Jim Kaler's Stars, University of Illinois:ELTANIN (Gamma Draconis)