Alpha Librae
Encyclopedia
Alpha Librae is the second brightest star
in the constellation
Libra
(despite its Bayer designation
as alpha). It has the traditional name Zubenelgenubi. The name, from Arabic
الزبن الجنوبي (al-zuban al-janūbiyy), means "southern claw" and was coined before Libra was recognized as distinct from Scorpius
. The alternate names Kiffa Australis and Elkhiffa Australis, partial Latin
translations
of Arabic al-kiffah al-janūbiyy, mean "southern pan (of the scales)". Another name used in older astronomy texts, equivalent to "southern scale or pan", was Lanx Australis.
from the Sun
.
Its two stars are separated in the sky by an angular distance of 231" (3'51"). The position angle
of the companion is 314 degrees. The brighter of the two is a white star of spectral type
A3, with an apparent brightness of 2.8 and an absolute brightness of 1.1, designated
Alpha-2 Librae (α2 Lib). Its companion is a type F4 star of apparent brightness 5.2 and absolute brightness 3.5, designated Alpha-1 Librae (α1 Lib).
Alpha Librae is close to the ecliptic
so it can be easily occulted
by the Moon
and (very rarely) by planet
s. The next occultation by a planet will be by Mercury
on 10 November 2052.
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....
Libra
Libra (constellation)
Libra is a constellation of the zodiac. Its name is Latin for weighing scales, and its symbol is . It is fairly faint, with no first magnitude stars, and lies between Virgo to the west and Scorpius to the east.-Notable features:]...
(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...
as alpha). It has the traditional name Zubenelgenubi. The name, from 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...
الزبن الجنوبي (al-zuban al-janūbiyy), means "southern claw" and was coined before Libra was recognized as distinct from Scorpius
Scorpius
Scorpius, sometimes known as Scorpio, is one of the constellations of the zodiac. Its name is Latin for scorpion, and its symbol is . It lies between Libra to the west and Sagittarius to the east...
. The alternate names Kiffa Australis and Elkhiffa Australis, partial 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...
translations
Translations
Translations is a three-act play by Irish playwright Brian Friel written in 1980. It is set in Baile Beag , a small village at the heart of 19th century agricultural Ireland...
of Arabic al-kiffah al-janūbiyy, mean "southern pan (of the scales)". Another name used in older astronomy texts, equivalent to "southern scale or pan", was Lanx Australis.
Description
Alpha Librae is visual binary located approximately 77 light yearsLight 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"....
from the 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...
.
Its two stars are separated in the sky by an angular distance of 231" (3'51"). The position angle
Angle
In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...
of the companion is 314 degrees. The brighter of the two is a white star 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...
A3, with an apparent brightness of 2.8 and an absolute brightness of 1.1, designated
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...
Alpha-2 Librae (α2 Lib). Its companion is a type F4 star of apparent brightness 5.2 and absolute brightness 3.5, designated Alpha-1 Librae (α1 Lib).
Viewing
 Alpha Librae, on the right, is the westernmost bright star in the constellation Libra Libra (constellation) Libra is a constellation of the zodiac. Its name is Latin for weighing scales, and its symbol is . It is fairly faint, with no first magnitude stars, and lies between Virgo to the west and Scorpius to the east.-Notable features:]... , and is very close to the ecliptic Ecliptic The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun... . |
α1 Lib and α2 Lib on DSS2 Digitized Sky Survey The Digitized Sky Survey is a digital version of several photographic atlases of the night sky, and an ongoing project to produce more digital versions of photographic astronomical datasets.- Versions and source material :... sky survey; 1° view Credit: AAO Anglo-Australian Observatory The Australian Astronomical Observatory , formerly the Anglo-Australian Observatory, is an optical/near-infrared astronomy observatory with its headquarters in suburban Sydney, Australia... /STScI/WikiSky |
Alpha Librae is close to the ecliptic
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
so it can be easily occulted
Occultation
An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...
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...
and (very rarely) by planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s. The next occultation by a planet will be by Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...
on 10 November 2052.