Delta Virginis
 Location of δ Virginis (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Virgo |
| Right ascension | 12h 55m 36.20861s[1] |
| Declination | +3° 23′ 50.8932″[1] |
| Apparent magnitude (V) | 3.402[2] |
| Characteristics | |
| Spectral type | M3 III[3] |
| U−B color index | +1.825[2] |
| B−V color index | +1.565[2] |
| Variable type | Semiregular |
| Astrometry | |
| Radial velocity (Rv) | –18.14 ± 0.55[4] km/s |
| Proper motion (μ) | RA: –469.99[1] mas/yr Dec.: –52.83[1] mas/yr |
| Parallax (π) | 16.44 ± 0.22[1] mas |
| Distance | 198 ± 3 ly (60.8 ± 0.8 pc) |
| Absolute magnitude (MV) | –2.4 ± 0.3[5] |
| Details | |
| Mass | 1.4 ± 0.3[5] M☉ |
| Radius | 48[4] R☉ |
| Luminosity | 468[4] L☉ |
| Surface gravity (log g) | 1.0[4] cgs |
| Temperature | 3,999[4] K |
| Metallicity [Fe/H] | –0.16[4] dex |
| Rotational velocity (v sin i) | 6.0[4] km/s |
| Other designations | |
Delta Virginis (δ Vir, δ Virginis) is a star in the zodiac constellation of Virgo. It has the traditional name Auva. With an apparent visual magnitude of 3.4,[2] this star is bright enough to be seen with the naked eye. Based upon parallax measurements, it is located at a distance of about 198 light-years (61 parsecs) from Earth.[1]
Properties
The spectrum of this star matches a stellar classification of M3 III,[3] which places it among the category of evolved stars called red giants. Indeed, the outer atmosphere of this star has expanded to around 48 times the radius of the Sun.[4] Even though it has just 1.4 times the mass of the Sun,[5] this wide envelope gives it a luminosity of roughly 468 times the Sun's.[4] This energy is being radiated from a relatively cool outer atmosphere that has an effective temperature of nearly 4,000 K.[4] It is this cool temperature that gives it the orange-red glow of an M-type star.[7]
The outer envelope of this star is undergoing a type of pulsation that occurs in a class of variable stars known as semiregular variables[8] and its brightness varies from magnitude +3.32 to +3.40. Based upon frequency analysis of the observed light curve, the star's variability exhibits multiple periods of pulsation. The detected periods are 13.0, 17.2, 25.6, 110.1 and 125.8 days.[8] This is a high-velocity star with a peculiar velocity of more than 30 km s−1 relative to the mean motion of other stars in the vicinity.[9]
Delta Virginis is a possible binary star, as an 11th magnitude star is located at an angular separation of 80 arcseconds. This K-type dwarf may have an orbital period of over 200,000 years, but this has not been confirmed.[10]
Etymology
The medieval names Auva, Al Awwa, and Minelauva are from the Arabic عوى cawwa’, meaning "barking (dog)". This star, along with β Vir(Zavijava), γ Vir (Porrima), η Vir (Zaniah) and ε Vir (Vindemiatrix), were Al ʽAwwāʼ, the Barker.[11]
In Chinese, 太微左垣 (Tài Wēi Zuǒ Yuán), meaning Left Wall of Supreme Palace Enclosure, refers to an asterism consisting of δ Virginis, η Virginis, γ Virginis, ε Virginis and α Comae Berenices.[12] Consequently, δ Virginis itself is known as 太微左垣三 (Tài Wēi Zuǒ Yuán sān, English: the Third Star of Left Wall of Supreme Palace Enclosure.),[13] representing 東次相 (Dōngcìxiāng), meaning The Second Eastern Minister.[14] 東次相 (Dōngcìxiāng), westernized into Tsze Seang by R.H. Allen and the meaning is "the Second Minister of State" [15]
References
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- ↑ (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, ISBN 978-986-7332-25-7.
- ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ↑ (Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Virgo
