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M Hydrae
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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 14h 46m 00.08s[1] |
| Declination | −25° 26′ 35.44″[1] |
| Apparent magnitude (V) | 4.95[2] (5.2 + 7.4)[3] |
| Characteristics | |
| Evolutionary stage | AGB+main sequence[2] |
| Spectral type | F2III+G1V[2] |
| B−V color index | +0.35[4] |
| Astrometry | |
| Radial velocity (Rv) | 5.4±3.8[1] km/s |
| Proper motion (μ) | RA: 151.50[1] mas/yr Dec.: 107.28[1] mas/yr |
| Parallax (π) | 33.02±0.92 mas[1] |
| Distance | 99 ± 3 ly (30.3 ± 0.8 pc) |
| Absolute magnitude (MV) | 2.73[4] |
| Details | |
| 54 Hya A | |
| Mass | 1.35±0.15 M☉ |
| Radius | 1.71 R☉ |
| Temperature | 7,158 K |
| Rotational velocity (v sin i) | 112.5 km/s |
| 54 Hya B | |
| Mass | 1.3±0.1 M☉ |
| Radius | 1.2±0.1 R☉ |
| Other designations | |
| m Hya, 54 Hya, CD−24°11661, GJ 9494, HD 129926, HIP 72197, HR 5497, SAO 182855, ADS 9375, WDS J14460-2527[1] | |
| Database references | |
| SIMBAD | data |
54 Hydrae, also known by its Bayer designation m Hydrae, is a binary star 99 light-years from Earth, easily divisible in small amateur telescopes. The primary is a yellow star of magnitude 5.2 and the secondary is a purple star of magnitude 7.4. They are separated by 8.4 arcseconds.[3]
Nomenclature
[edit]54 Hydrae is the star’s Flamsteed designation, while it also has the Bayer designation m Hydrae, which was not given by Johann Bayer, but by Benjamin Apthorp Gould, which he included in his Uranometria Argentina.[5] It should not be confused with 42 Hydrae, which has the Bayer designation Mu Hydrae. Before Gould, it was also included in the obsolete constellation of Turdus Solitarius, where it was designated Delta (δ) Turdii Solitarii.[6]
In Chinese, 折威 (Shé Wēi), meaning Executions (asterism), refers to an asterism consisting of σ Librae, 50 Hydrae, 3 Librae, 4 Librae and 12 Librae.[7] It was considered as an “extra” star, and was given the Chinese name 折威增三 (Shé Wēi Zēng Sān, English: the Third Extra Star of Executions).[8]
References
[edit]- ^ a b c d e f g "54 Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-01-17.
- ^ a b c https://theskylive.com/sky/stars/54-hydrae-star
- ^ a b http://www.dibonsmith.com/hya_54.htm
- ^ a b Hoffleit, Dorrit; Jaschek, Carlos (1991). The Bright Star Catalogue. Yale University Observatory. Bibcode:1991bsc..book.....H. VizieR Detail Page
- ^ http://www.uranometriaargentina.com/
- ^ http://www.ianridpath.com/startales/solitaire.html Ian Ridpath's Star Tales - Turdus Solitarius]
- ^ (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, ISBN 978-986-7332-25-7.
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 28 日 Archived 2011-07-16 at the Wayback Machine
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