Epsilon Boötis
Encyclopedia
Epsilon Boötis (ε Boo, ε Boötis) is a double star
in the constellation
Boötes
. It has the traditional names Izar and Pulcherrima.
Epsilon Boötis consists of a bright orange giant and a smaller main sequence
star. The orange giant is a fairly late-stage star well into its stellar evolution
, having already exhausted its supply of hydrogen
fuel. By the time the smaller main sequence star reaches this point in its evolution, the larger star will have lost much of its mass in a planetary nebula
and will have evolved into a white dwarf
, and the pair will have essentially changed roles: the brighter star becoming the dim dwarf, while the lesser star will shine as a bright orange giant.
The name Izar is derived from the Arabic إزار ’izār "veil", and Pulcherrima is Latin for "loveliest". Other historical names are Mirak, from Arabic المراق al-maraqq "the loins", and Mizar.
In Chinese
, , meaning Celestial Lance
, refers to an asterism consisting of ε Boötis, σ Boötis
and ρ Boötis. Consequently, ε Boötis itself is known as
In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Mintek al Aoua (منتقة ألعوع - minṭáqa al awwa), which was translated into Latin
as Cingulum Latratoris, meaning belt of barker.
In 1973, the Scottish
astronomer and science fiction writer Duncan Lunan
claimed to have managed to interpret a message caught in the 1920s by two Norwegian physicists that, according to his theory, came from a probe
orbiting the Moon
and sent there by the inhabitants of a planet orbiting Epsilon Boötis. The story was even reported in Time
magazine. Lunan later withdrew his Epsilon Boötis theory, presenting proofs against it and clarifying why he was brought to formulate it in the first place.
Double 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...
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....
Boötes
Boötes
Boötes is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from the Greek Βοώτης, Boōtēs, meaning herdsman or plowman...
. It has the traditional names Izar and Pulcherrima.
Epsilon Boötis consists of a bright orange giant and a smaller 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...
star. The orange giant is a fairly late-stage star well into 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...
, having already exhausted its supply of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
fuel. By the time the smaller main sequence star reaches this point in its evolution, the larger star will have lost much of its mass in a planetary nebula
Planetary nebula
A planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life...
and will have evolved into a 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...
, and the pair will have essentially changed roles: the brighter star becoming the dim dwarf, while the lesser star will shine as a bright orange giant.
The name Izar is derived from the Arabic إزار ’izār "veil", and Pulcherrima is Latin for "loveliest". Other historical names are Mirak, from Arabic المراق al-maraqq "the loins", and Mizar.
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 Lance
Root (Chinese constellation)
The Root mansion is one of the Twenty-eight mansions of the Chinese constellations. It is one of the eastern mansions of the Azure Dragon.-Asterisms:...
, refers to an asterism consisting of ε Boötis, σ Boötis
Sigma Boötis
Sigma Boötis is a star in the constellation Boötes.Sigma Boötis is a yellow-white F-type main sequence dwarf with an apparent magnitude of +4.47. It is approximately 50.4 light years from Earth....
and ρ Boötis. Consequently, ε Boötis itself is known as
In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Mintek al Aoua (منتقة ألعوع - minṭáqa al awwa), which was translated into Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
as Cingulum Latratoris, meaning belt of barker.
In 1973, the Scottish
Scottish people
The Scottish people , or Scots, are a nation and ethnic group native to Scotland. Historically they emerged from an amalgamation of the Picts and Gaels, incorporating neighbouring Britons to the south as well as invading Germanic peoples such as the Anglo-Saxons and the Norse.In modern use,...
astronomer and science fiction writer Duncan Lunan
Duncan Lunan
Duncan Alasdair Lunan, who hails from Troon, born on the 24 October 1945 is a Scottish author, with emphasis on astronomy, spaceflight and science fiction, as well as astronomer, science reporter, and teacher...
claimed to have managed to interpret a message caught in the 1920s by two Norwegian physicists that, according to his theory, came from a probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
orbiting 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...
and sent there by the inhabitants of a planet orbiting Epsilon Boötis. The story was even reported in Time
Time (magazine)
Time is an American news magazine. A European edition is published from London. Time Europe covers the Middle East, Africa and, since 2003, Latin America. An Asian edition is based in Hong Kong...
magazine. Lunan later withdrew his Epsilon Boötis theory, presenting proofs against it and clarifying why he was brought to formulate it in the first place.
In fiction
- See Epsilon Boötis in fiction.
- See Garth of Izar