Beta Tauri
Encyclopedia
Beta Tauri is the second brightest star
in the constellation
Taurus
, with an apparent magnitude
of 1.68. Because it is on the boundary of Taurus and Auriga
, it also has the redundant Bayer designation
Gamma Aurigae (γ Aur), which today is rarely used. The star has the traditional name Elnath—a reference to "the butting" of the bull's horns.
is -1.34, similar to another Taurean star, Maia
in the Pleiadian
star cluster
. Like Maia, Elnath is a B class giant
with a luminosity 700 times solar. However being approximately 130 light years
distant compared to Maia's estimated 360 light years, Elnath ranks as the second brightest star in the constellation.
Uniquely positioned along the plane of our Milky Way Galaxy
a few degrees west of the galactic anticenter
, Elnath heralds a rich collection of nebula
e and star cluster
s. Relative to our Sun
, β Tauri is notable for a high abundance of manganese
, but little calcium
and magnesium
. This star has begun to evolve away from the main sequence
.
This star can be occulted by the moon
. Such occultations occur when the moon's ascending node is near the vernal equinox, as is the case in 2007. Most occultations are visible only in parts of the Southern Hemisphere, because the star lies at the northern edge of the lunar occultation zone. Rarely, it may be occulted as far north as southern California
.
. Its visual companion, known as BD+28 795B, has a PA
of 239 degrees and is separated from the main star by 33.4 arcseconds.
In Chinese
, , meaning Five Chariots
, refers to an asterism consisting of β Tauri, ι Aurigae
, Capella
, β Aurigae
and θ Aurigae
. Consequently, β Tauri itself is known as
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....
Taurus
Taurus (constellation)
Taurus is one of the constellations of the zodiac. Its name is a Latin word meaning 'bull', and its astrological symbol is a stylized bull's head:...
, with an apparent 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...
of 1.68. Because it is on the boundary of Taurus and Auriga
Auriga (constellation)
Auriga is a constellation in the northern sky. Its name is Latin for 'charioteer' and its stars form a shape that has been associated with the pointed helmet of a charioteer. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains among the 88 modern...
, it also has the redundant 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...
Gamma Aurigae (γ Aur), which today is rarely used. The star has the traditional name Elnath—a reference to "the butting" of the bull's horns.
Properties
Elnath's absolute magnitudeAbsolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
is -1.34, similar to another Taurean star, Maia
Maia (star)
Maia is a star in the constellation Taurus. It is the fourth brightest star in the Pleiades open star cluster , after Alcyone, Atlas and Electra, in that order. The name Maia originates with the and . She is one of the seven daughters of Atlas and Pleione in Greek mythology—stars which...
in the Pleiadian
Pleiades (star cluster)
In astronomy, the Pleiades, or Seven Sisters , is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky...
star cluster
Open cluster
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way Galaxy, and many more are thought to exist...
. Like Maia, Elnath is a B class giant
Giant 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...
with a luminosity 700 times solar. However being approximately 130 light years
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
distant compared to Maia's estimated 360 light years, Elnath ranks as the second brightest star in the constellation.
Uniquely positioned along the plane of our Milky Way Galaxy
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
a few degrees west of the galactic anticenter
Galactic anticenter
The galactic anticenter is a theoretical point in the sky that lies directly opposite the center of the Milky Way galaxy. Because this point is relative, it will vary depending on the location of the observer; it is not an actual fixed point in space. Most of the time, this term refers to the...
, Elnath heralds a rich collection of nebula
Nebula
A nebula is an interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases...
e and star cluster
Star cluster
Star clusters or star clouds are groups of stars. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain less than...
s. Relative to our 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...
, β Tauri is notable for a high abundance of manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
, but little calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
and magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
. This star has begun to evolve away from the main sequence
Main sequence
The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...
.
This star can be occulted by the moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
. Such occultations occur when the moon's ascending node is near the vernal equinox, as is the case in 2007. Most occultations are visible only in parts of the Southern Hemisphere, because the star lies at the northern edge of the lunar occultation zone. Rarely, it may be occulted as far north as southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
.
Double star
There is a faint star that appears close enough to Elnath for astronomers to consider it a double starDouble star
In observational astronomy, a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. This can happen either because the pair forms a binary star, i.e...
. Its visual companion, known as BD+28 795B, has a PA
Position angle
Position angle, usually abbreviated PA, is a measurement derived from observing visual binary stars. It is defined as the angular offset in degrees of the secondary star to the primary, relative to the north celestial pole....
of 239 degrees and is separated from the main star by 33.4 arcseconds.
Etymology
Beta Tauri has the traditional name Elnath, El Nath, or Alnath, which comes from the Arabic word النطح an-naţħ, meaning "the butting" (i.e. the bull's horns). As in many other (but not all) Arabic star names, the article ال is transliterated literally as el, despite the fact that in Arabic pronunciation it is assimilated to the following n; it can also be omitted: Nath.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 Five Chariots
Five Chariots
Five Chariots is a constellation in Chinese astronomy.-Introduction:A five-star Chinese constellation that contains Auriga plus Beta Tauri. Also known as Gosha.-Stars:* Iota Aurigae* Alpha Aurigae* Beta Aurigae...
, refers to an asterism consisting of β Tauri, ι Aurigae
Iota Aurigae
Iota Aurigae is a star in the constellation Auriga. It has the traditional name Al Kab, short for Kabdhilinan, from the Arabic الكعب ذي العنان al-kacb ðīl-cinān "the ankle of the rein holder "...
, Capella
Capella
Capella can refer to:* Capella , a bright star in the constellation of Auriga* Capella , an impact crater on the Moon* Capella, Queensland, a small town in Central Queensland* Capella Island, a minor island of the U.S...
, β Aurigae
Beta Aurigae
Beta Aurigae , traditionally named Menkalinan, is a white subgiant ternary star system approximately 85 light-years away in the constellation Auriga.- Nomenclature :...
and θ Aurigae
Theta Aurigae
Theta Aurigae is a binary star in the constellation Auriga. It is approximately 173 light-years from Earth. Rarely used proper names for this star include Bogardus and Mahasim, the latter from the Arabic المِعْصَم al-micşam "wrist" , which was also used for Eta Aurigae.The primary, θ Aurigae A,...
. Consequently, β Tauri itself is known as
See also
- Lists of stars in the constellation Taurus
- Class B Stars
- Beta Tauri in fiction
External links
- Jim Kaler's Stars:Elnath
- Image of Elnath from APODAstronomy Picture of the DayAstronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...