Eta Aquarii
Template:Location mark Location of η Aquarii (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 4.04[2] |
| Characteristics | |
| Spectral type | B9IV-Vn[3] or B8/9V[4] |
| U−B Template:Engvar | −0.28[5] |
| B−V Template:Engvar | −0.10[5] |
| Astrometry | |
| Radial velocity (Rv) | –8.0[2] km/s |
| Proper motion (μ) | RA: +89.74 mas/yr[1] Dec.: −56.10 mas/yr[1] |
| Parallax (π) | 19.43±0.25 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | 0.31±0.15[6] |
| Details[6] | |
| Mass | 2.96±0.04 Template:Solar mass |
| Radius | 2.77±0.30 Template:Solar radius |
| Luminosity | 102.8 Template:Solar luminosity |
| Surface gravity (log g) | 4.02±0.04 cgs |
| Temperature | Script error: No such module "val". K |
| Rotational velocity (v sin i) | 271±32 km/s |
| Age | 65[7] Myr |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[8] | |
| Database references | |
| SIMBAD | data |
Script error: No such module "Check for unknown parameters".
Eta Aquarii is a star in the equatorial constellation of Aquarius. Its identifier is a Bayer designation that is Latinized from η Aquarii, and abbreviated Eta Aqr or η Aqr, respectively. The star is visible to the naked eye with an apparent visual magnitude of 4.04.[2] The distance to this star, as determined by parallax measurements, is about Script error: No such module "convert"..[1] It is drifting closer to the Sun with a radial velocity of –8 km/s.[2] Eta Aquarii is near the radiant of a meteor shower named after it.
The stellar classification of Eta Aquarii is B9IV-Vn,[3] which may indicate that it is beginning to evolve away from the main sequence into a subgiant as the supply of hydrogen at its core becomes exhausted. It is 65[7] million years old and is spinning rapidly with a high projected rotational velocity of 271 km/s.[6] This rotation is causing an equatorial bulge, giving the star an oblate figure with a 24% larger radius at the equator than at the poles.[9] The Doppler effect from the rapid rotation is causing the absorption lines in the star's spectrum to blur, as indicated by the 'n' suffix in the star's classification. Eta Aquarii has an estimated 2.96 times the mass of the Sun and 2.8 times the Sun's radius. The star is radiating 103 times the luminosity of the Sun from its photosphere at an effective temperature of 11,042 K.[6]
Naming
This star, along with γ Aqr (Sadachbia), π Aqr (Seat) and ζ Aqr (Sadaltager / Achr al Achbiya), were al Aḣbiyah (الأخبية), the Tent.[10][11]
In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Tomb, refers to an asterism consisting of η Aquarii, γ Aquarii, ζ Aquarii, π Aquarii.[12] Consequently, the Chinese name for η Aquarii itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[13]
References
<templatestyles src="Reflist/styles.css" />
- ↑ a b c d e Script error: No such module "citation/CS1".
- ↑ a b c d Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ a b c d Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ Template:Cite simbad
- ↑ 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 AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 16 日 Template:Webarchive
Script error: No such module "Check for unknown parameters".