Alpha Coronae Australis
Template:Location mark Location of α CrA (circled) | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 4.102[2] |
| Characteristics | |
| Spectral type | A2V[3] |
| U−B Template:Engvar | +0.06[4] |
| B−V Template:Engvar | +0.04[4] |
| Astrometry | |
| Radial velocity (Rv) | Template:Val[5] km/s |
| Proper motion (μ) | RA: +84.87[1] mas/yr Dec.: −95.99[1] mas/yr |
| Parallax (π) | 26.02±0.25 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | 1.11[6] |
| Details | |
| Mass | 2.57[7] Template:Solar mass |
| Radius | 2.21[3] Template:Solar radius |
| Luminosity | 31[8] Template:Solar luminosity |
| Surface gravity (log g) | 4.08[7] cgs |
| Temperature | Template:Val[7] K |
| Rotational velocity (v sin i) | 195[9] km/s |
| Age | 254[2] Myr |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[4] | |
| Database references | |
| SIMBAD | data |
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Alpha Coronae Australis or α Coronae Australis, officially named Meridiana (Template:IPAc-en),[10] is the brightest star in the constellation of Corona Australis and is located about 125 light-years from Earth.
Nomenclature
α Coronae Australis (Latinised to Alpha Coronae Australis) is the star's Bayer designation.
It is the only star in the constellation with a traditional proper name, Alphekka Meridiana (Latin for 'Alphekka South'), after Alphecca, the brightest star in the constellation Corona Borealis.Script error: No such module "Unsubst". The name Alphecca or Alphekka is Arabic, short for نير الفكّة nayyir al-fakka "the bright (star) of the broken (ring of stars)".[11] In 2016, the IAU organized a Working Group on Star Names (WGSN)[12] to catalog and standardize proper names for stars. The WGSN approved the name Meridiana for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[10]
In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning River Turtle, refers to an asterism consisting of Alpha Coronae Australis, Alpha Telescopii, Eta1 Coronae Australis, Zeta Coronae Australis, Delta Coronae Australis, Beta Coronae Australis, Gamma Coronae Australis, Epsilon Coronae Australis, HD 175362, Kappa2 Coronae Australis and Theta Coronae Australis.[13] Consequently, the Chinese name for Alpha Coronae Australis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.).[14]
Properties
Alpha Coronae Australis belongs to the spectral class A2Va, making it an A-type star like Vega. Like the latter, it has excess infrared radiation, which indicates it may be ringed by a disk of dust.[8] It has an apparent magnitude of +4.10.[4] The star's mass and radius are estimated at 2.3 times the Sun's mass and radius. With an effective temperature of roughly 9,100 K, the star radiates a total luminosity of about 31 times the Sun's.[8] This star is roughly 254 million years old.[2] A rapidly rotating star, it spins at almost 200 km per second at the equator, making a complete revolution in approximately 14 hours,[9] close to its breakup velocity.
See also
- Lists of stars in the constellation Corona Australis
- Class A Stars
- Vega
- Circumstellar disk
References
Template:Stars of Corona Australis
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- ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
- ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.