Gamma Virginis
Location of γ Virginis (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Virgo |
| Right ascension | 12h 41m 39.64344s[1] |
| Declination | −01° 26′ 57.7421″[1] |
| Apparent magnitude (V) | 2.74 (3.650/3.560)[2] |
| Characteristics | |
| Spectral type | F0 V/F0 V[2] |
| U−B color index | −0.05 |
| B−V color index | +0.36 |
| Variable type | not variable[3] |
| Astrometry | |
| Radial velocity (Rv) | −19.5[4] km/s |
| Proper motion (μ) | RA: −614.76[1] mas/yr Dec.: 61.34[1] mas/yr |
| Parallax (π) | 85.58±0.60 mas[1] |
| Distance | 38.1 ± 0.3 ly (11.68 ± 0.08 pc) |
| Absolute magnitude (MV) | 2.41[5] |
| Orbit[6] | |
| Companion | Gamma Virginis B |
| Period (P) | 169.104±0.011 yr |
| Semi-major axis (a) | 3.639±0.008″ |
| Eccentricity (e) | 0.8815±0.00018 |
| Inclination (i) | 149.46±0.16° |
| Longitude of the node (Ω) | 35.34±0.42° |
| Periastron epoch (T) | 2005.511±0.00019 |
| Argument of periastron (ω) (secondary) | 255.02±0.37° |
| Details | |
| A | |
| Mass | 1.4±0.05[6] M☉ |
| Radius | 1.45[7] R☉ |
| Luminosity | 4.27[8] L☉ |
| Surface gravity (log g) | 4.27[8] cgs |
| Temperature | 6,922±112[8] K |
| Metallicity [Fe/H] | −0.08±0.06[9] dex |
| Rotational velocity (v sin i) | 29.7[8] km/s |
| Age | 1.46+0.2 −0.18[9] Gyr |
| B | |
| Mass | 1.4±0.05[6] M☉ |
| Radius | 1.45[7] R☉ |
| Luminosity | 4.63+0.15 −0.14[10] L☉ |
| Surface gravity (log g) | 4.49[11] cgs |
| Temperature | 6,871±62[10] K |
| Metallicity [Fe/H] | −0.07[11] dex |
| Rotational velocity (v sin i) | 23[10] km/s |
| Other designations | |
| Porrima, Antevorta, 29 Virginis, BD−00°2601, GCTP 2924.00, Gl 482 AB, HIP 61941, LHS 2604, SAO 138917, WDS 12417-0127 | |
| γ Vir A: HD 110379, HR 4825, LFT 937, LTT 4843 | |
| γ Vir B: HD 110380, HR 4826, LFT 937, LTT 4844 | |
| Database references | |
| SIMBAD | γ Vir |
| γ Vir A | |
| γ Vir B | |
Gamma Virginis (γ Virginis, abbreviated Gamma Vir, γ Vir), officially named Porrima /ˈpɒrɪmə/,[12][13] is a binary star system in the constellation of Virgo. It consists of two almost identical main sequence stars at a distance of about 38 light-years.
Name
[edit | edit source]γ Virginis (Latinised to Gamma Virginis) is the star's Bayer designation.
The traditional name Porrima derives from Ancient Rome: Porrima, also known as Antevorta, was one of the Camenae or goddesses of prophecy.[14] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[16] included a table of the first two batches of names approved by the WGSN; which included Porrima for this star.
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'.[17] This star, along with Beta Virginis (Zavijava), Eta Virginis (Zaniah), Delta Virginis (Minelauva) and Epsilon Virginis (Vindemiatrix), were Al ʽAwwāʼ, the Barker.[14]
In Chinese, 太微左垣 (Tài Wēi Zuǒ Yuán), meaning Left Wall of Supreme Palace Enclosure, refers to an asterism consisting of Gamma Virginis, Eta Virginis, Delta Virginis, Epsilon Virginis and Alpha Comae Berenices.[18] Consequently, the Chinese name for Gamma Virginis itself is 太微左垣二 (Tài Wēi Zuǒ Yuán èr, English: the Second Star of Left Wall of Supreme Palace Enclosure.),[19] representing 東上相 (Dōngshǎngxiāng), meaning The First Eastern Minister.[20] 東上相 (Dōngshǎngxiāng), westernized into Shang Seang by R. H. Allen and the meaning is "the High Minister of State".[14]
Properties
[edit | edit source]Gamma Virginis is a binary star, consisting of two stars of nearly equal apparent magnitudes 3.65 and 3.56, and of spectral type F0V.[2] With an orbital period of 168.93 years,[21][6] it was an easy object for amateur astronomers until the beginning of the 1990s, but in 2011 the smaller apparent distance between the stars requires a larger telescope or special techniques such as speckle interferometry,[21][6] adaptive optics[22] or optical interferometry[23] to resolve the individual components. The last time they were at periapsis was in 1836. The distance became 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.
Gamma Virginis has been reported to be slightly variable,[24] but this is now considered unlikely.[3]
At 2.8 degrees north of the ecliptic, Gamma Virginis it can be occulted by the Moon and (rarely) by planets. In June 2011 Saturn passed a quarter of a degree south of Porrima.
Based upon X-ray emissions—an indicator of the strength of the stellar magnetic field—this system has an estimated age of 1.14 billion years.[25]
Changes of distance and position angle
[edit | edit source]This table shows the apparent distance between the two stars and their relative position angle: the first three columns show data predicted from an orbit calculated in 1937, the next two columns show in 2006,[26] the next three columns show observations reported by the Hanwell Community Observatory.[27]
| 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″ | 219° | ||
| 2004 | 1.2″ | 246 | 0.68″ | 218.4 | 2004 Dec. | 0.4″ | 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 | |||
References
[edit | edit source]- ^ a b c d e Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Note: see VizieR catalogue I/311.
- ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c d e Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gamma Virginis' database entry at VizieR.
- ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value)..
- ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived January 30, 2011, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ^ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived August 10, 2010, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Christopher Taylor, Hanwell Community Observatory[permanent dead link]
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