Epsilon Aquarii
Template:Location mark Location of ε Aquarii (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 3.77[2] |
| Characteristics | |
| Evolutionary stage | Main sequence[3] or subgiant[4] |
| Spectral type | A1 V[2] + KV[4] |
| U−B Template:Engvar | +0.029[5] |
| B−V Template:Engvar | −0.001[5] |
| Variable type | Constant[6] |
| Astrometry | |
| Radial velocity (Rv) | Script error: No such module "val".[1] km/s |
| Proper motion (μ) | RA: +33.923 mas/yr[1] Dec.: −34.926 mas/yr[1] |
| Parallax (π) | 13.3619±0.3737 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | −0.46[7] |
| Orbit[4] | |
| Primary | A |
| Companion | B |
| Period (P) | 1.2 years |
| Semi-major axis (a) | Script error: No such module "val". Script error: No such module "val". |
| Details | |
| A | |
| Mass | Script error: No such module "val".[3] Template:Solar mass |
| Radius | 4.2[4] Template:Solar radius |
| Luminosity | Script error: No such module "val".[8] Template:Solar luminosity |
| Surface gravity (log g) | Script error: No such module "val".[9] cgs |
| Temperature | Script error: No such module "val".[9] K |
| Metallicity [Fe/H] | Script error: No such module "val".[6] dex |
| Rotational velocity (v sin i) | Script error: No such module "val".[7] km/s |
| Age | 388[9] Myr |
| B | |
| Mass | 0.61[4] Template:Solar mass |
| Radius | 0.57[4] Template:Solar radius |
| Temperature | 4,070[4] K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[10] | |
| Database references | |
| SIMBAD | data |
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Epsilon Aquarii is a binary star system in the equatorial zodiac constellation of Aquarius, located near the western constellation border with Capricornus. Its identifier is a Bayer designation that is Latinized from ε Aquarii, and abbreviated Eps Aqr or ε Aqr, respectively. It has the proper name Albali Template:IPAc-en, now formally recognized by the IAU.[11][12] This system is visible to the naked eye as a point of light with an apparent visual magnitude of 3.77,[2] and has an absolute magnitude of −0.46.[7] Based upon parallax measurements taken by the Gaia spacecraft, it is located at a distance of approximately Script error: No such module "convert". from Earth.[1] The star is drifting closer with a radial velocity of −20 km/s.[1]
Properties
The primary member has a stellar classification of A1 V,[2] indicating it is an A-type main-sequence star. However, isochrone fitting suggests this star has recently evolved away from the main sequence and is now a subgiant star.[4] It is estimated to be 388[9] million years old with a high rate of spin, showing a projected rotational velocity of around 118 km/s.[7] The elemental abundances in the stellar atmosphere are close to solar, with pronounced underabundances of aluminium and strontium.[6] The star has three[3] times the mass of the Sun and about 4.2[4] times the Sun's radius. It is radiating 161[8] times the luminosity of the Sun from its photosphere at an effective temperature of 9,622 K.[9]
The binary nature of this system was discovered in 2023 based on observations from the European Southern Observatory. The secondary component is a K-type main-sequence star with 0.6 times the mass and 0.57 times the radius of the Sun. Located at a projected separation of 26 milliarcseconds from the primary, this translates to a physical separation of 1.7 astronomical units. Albali A and B complete an orbit around their center of mass each 1.2 years.[4]
Nomenclature
ε Aquarii (Latinised to Epsilon Aquarii) is the star's Bayer designation.
It bore the traditional name, Albali, from the Arabic البالع (albāli‘), meaning "the swallower". (See also Albulaan.) Along with Mu Aquarii (Albulaan) and Nu Aquarii (also Albulaan), they were al Bulaʽ (البلع), meaning "the Swallower".[13][14] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalogue and standardize proper names for stars. The WGSN approved the name Albali for this star on 12 September 2016, and it is now so included in the List of IAU-approved Star Names.[12]
In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, it was designated Nir Saad Bula (نير سعد ألبلع nayyir sa'd al bulaʽ), which was translated into Latin as Lucida Fortunæ Dissipantis, meaning "the brightest of luck of the swallower".[16]
In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Girl (asterism), refers to an asterism consisting of Epsilon Aquarii, Mu Aquarii, 4 Aquarii, 5 Aquarii and 3 Aquarii.[17] Consequently, the Chinese name for Epsilon Aquarii itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx).[18]
References
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- ↑ a b c d Script error: No such module "citation/CS1".
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- ↑ Template:Cite simbad
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
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- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ 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.
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