Gamma Virginis
Encyclopedia
Gamma Virginis is a star in the constellation
Virgo
. It has the traditional names Porrima, Postvarta and Arich.
Gamma Virginis is a binary star
, consisting of two stars of approximately equal apparent magnitude
s 3.48 and 3.50, and of spectral type
F0V. With an orbital period
of 168.93 years it was an easy object for amateur astronomers until the beginning of the 1990s, but now the smaller apparent distance between the stars requires a larger telescope. The last time they were at periapsis
was in 1836. The distance will again be wide enough in 2020 to view with a small telescope. The star system has a combined apparent magnitude of 2.9. The system is 39 light years away from the Sun
.
As Gamma Virginis is close to the ecliptic
, it can be occulted
by the Moon
and (extremely rarely) by planet
s. In June 2011, Saturn came within a quarter of a degree from Porrima.
, sisters and assistants of Carmenta
or Carmentis, worshiped and at times invoked by their women.
In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Laouiyet al Aoua, which was translated into Latin
as Angulus Latratoris, meaning the angle of the barker. This star, along with β Vir
(Zavijava), η Vir
(Zaniah), δ Vir
(Auva) and ε Vir
(Vindemiatrix), were Al ʽAwwāʼ, the Barker.
In Chinese, , meaning Left Wall of Supreme Palace Enclosure
, refers to an asterism consisting of γ Virginis, η Virginis
, δ Virginis
, ε Virginis
and α Comae Berenices
. Consequently, γ Virginis itself is known as , representing , meaning The First Eastern Minister. 東上相 (Dōngshǎngxiāng), westernized into Shang Seang by R.H. Allen and the meaning is "the High Minister of State"
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....
Virgo
Virgo (constellation)
Virgo is one of the constellations of the zodiac. Its name is Latin for virgin, and its symbol is . Lying between Leo to the west and Libra to the east, it is the second largest constellation in the sky...
. It has the traditional names Porrima, Postvarta and Arich.
Gamma Virginis is a binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
, consisting of two stars of approximately equal 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...
s 3.48 and 3.50, and 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...
F0V. With an orbital period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
of 168.93 years it was an easy object for amateur astronomers until the beginning of the 1990s, but now the smaller apparent distance between the stars requires a larger telescope. The last time they were at periapsis
Apsis
An apsis , plural apsides , is the point of greatest or least distance of a body from one of the foci of its elliptical orbit. In modern celestial mechanics this focus is also the center of attraction, which is usually the center of mass of the system...
was in 1836. The distance will again be wide enough in 2020 to view with a small telescope. The star system has a combined apparent magnitude of 2.9. The system is 39 light years away 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...
.
As Gamma Virginis 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...
, it can be 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 (extremely 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. In June 2011, Saturn came within a quarter of a degree from Porrima.
Changes of distance and position angle
This table shows the apparent distance between the two stars and their relative position angle: first three columns show data predicted from an orbit calculated in 1937, the next two columns show in 2006, the next three columns show observations reported by the Hanwell Community Observatory.| Predicted from 1937 Strand orbit | Predicted from 2006 Docobo orbit | Observations 2003 to 2005 | |||||
|---|---|---|---|---|---|---|---|
| Year | distance | position angle | distance | position angle | Date | distance | position angle |
| 1995 | 2.5" | 280 | 2,25" | 277.6 | |||
| 2000 | 1.8" | 267 | 1.50" | 260.9 | |||
| 2002 | 1.5" | 259 | 1.13" | 247.5 | |||
| 2003 | 0.92" | 236.6 | 2003 Dec. | 0.6 arcsec. | 219° | ||
| 2004 | 1.2" | 246 | 0.68" | 218.4 | 2004 Dec. | 0.4 arcsec. | 177° |
| 2005 | 0.44" | 179.8 | 2005 April | 0.27-0.29" | 161±0.6° | ||
| 2006 | 0.8" | 221 | 0.41" | 103.5 | |||
| 2008 | 0.4" | 126 | 0.93" | 41.0 | |||
| 2010 | 0.9" | 44 | 1.39" | 23.6 |
Name
Porrima was the names of two ancient goddesses of prophecy - the CarmenaeCamenae
In Roman mythology, the Camenae were originally goddesses of childbirth, wells and fountains, and also prophetic deities.There were four Camenae:*Carmenta*Egeria*Antevorta, or Porrima...
, sisters and assistants of Carmenta
Carmenta
In ancient Roman religion and myth, Carmenta was a goddess of childbirth and prophecy, associated with technological innovation as well as the protection of mothers and children, and a patron of midwives...
or Carmentis, worshiped and at times invoked by their women.
In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Laouiyet al Aoua, 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 Angulus Latratoris, meaning the angle of the barker. This star, along with β Vir
Beta Virginis
Beta Virginis is a star in the constellation Virgo. It has the traditional names Zavijava and Alaraph...
(Zavijava), η Vir
Eta Virginis
Eta Virginis is a star in the constellation Virgo. It has the traditional name Zaniah .Zaniah is about 204 light years distant from the Sun, and has apparent magnitude +3.9 and is of spectral type A2IV....
(Zaniah), δ Vir
Delta Virginis
Delta Virginis is a red giant star in the constellation Virgo. It also has the traditional name Auva.It has a spectral type of M3-III, and an magnitude of 3.38, bright enough to be seen with the naked eye...
(Auva) and ε Vir
Epsilon Virginis
Epsilon Virginis is a star in the constellation Virgo. It has the traditional name Vindemiatrix, which comes from Greek through Latin and means Grape Gatherer....
(Vindemiatrix), were Al ʽAwwāʼ, the Barker.
In Chinese, , meaning Left Wall of Supreme Palace Enclosure
Supreme Palace enclosure
Tai Wei Yuan, the Supreme Palace Enclosure , is one of the San Yuan or Three enclosures. Stars and constellations of this group are visible during autumn in the Northern Hemisphere .-Asterisms:The asterisms are :...
, refers to an asterism consisting of γ Virginis, η Virginis
Eta Virginis
Eta Virginis is a star in the constellation Virgo. It has the traditional name Zaniah .Zaniah is about 204 light years distant from the Sun, and has apparent magnitude +3.9 and is of spectral type A2IV....
, δ Virginis
Delta Virginis
Delta Virginis is a red giant star in the constellation Virgo. It also has the traditional name Auva.It has a spectral type of M3-III, and an magnitude of 3.38, bright enough to be seen with the naked eye...
, ε Virginis
Epsilon Virginis
Epsilon Virginis is a star in the constellation Virgo. It has the traditional name Vindemiatrix, which comes from Greek through Latin and means Grape Gatherer....
and α Comae Berenices
Alpha Comae Berenices
Alpha Comae Berenices is a star in the constellation Coma Berenices . Although it has the Bayer designation "alpha", at magnitude 4.32 it is actually fainter than Beta Comae Berenices. It has the traditional name Diadem. It is said to represent the crown worn by Queen Berenice...
. Consequently, γ Virginis itself is known as , representing , meaning The First Eastern Minister. 東上相 (Dōngshǎngxiāng), westernized into Shang Seang by R.H. Allen and the meaning is "the High Minister of State"