| Tau Hercules | |||
|---|---|---|---|
| Star | |||
| Observational data ( Age J2000.0 ) | |||
| Right ascension | |||
| Declination | |||
| Distance | 310 ± 20 St. years (96 ± 5 pc ) [2] | ||
| Visible magnitude ( V ) | 3.89 [1] | ||
| Constellation | Hercules | ||
| Astrometry | |||
| Radial velocity ( R v ) | -13.8 [1] km / s | ||
| Own movement (μ) | RA: -13.15 [1] Dec: +39.31 [1] | ||
| Parallax (π) | 10.37 [3] ± 0.53 mas | ||
| Absolute magnitude (V) | -1.03 [4] | ||
| Specifications | |||
| Spectral class | B5IV [1] | ||
| Color Index ( B - V ) | -0.155 [5] | ||
| Color Index ( U - B ) | -0.57 [5] | ||
| physical characteristics | |||
| Weight | 4.9 [6] M ☉ | ||
| Radius | 3.55 ± 0.19 [7] R ☉ | ||
| Age | 1 [6] billion years | ||
| Temperature | 15 615 ± 301 [7] K | ||
| Luminosity | 700 [6] L ☉ | ||
| Metallicity | 141% [8] | ||
| Rotation | 46 [9] km / s | ||
| |||
| Database Information | |||
| SIMBAD | data | ||
Tau Hercules ( τ Herculis, τ Her ) is a fourth magnitude star in the constellation Hercules . It is a white-blue subgiant , seven hundred times brighter than the Sun. Its traditional name Rukbalgeti Shemali is of Arab origin and shares some etymological characteristics with the stars Rukbakh and Zuben El Shemali , designating the "northern knee" of Hercules [10] .
Properties
Tau Hercules has a spectral classification of B5IV. Its mass is 4.9 times that of the sun [6] . Although its apparent magnitude is only 3.89 m , its absolute magnitude , like all B-class stars is −1.0 m . The measurements made by the Hipparcos satellite made it possible to estimate the distance to the star at about 96 parsecs from Earth or 310 ± 20 light years . The total bolometric brightness is 700 times more than the sun. Like all stars of this spectral class, it is very bright.
North Star
Tau Hercules is one of eight bright stars in the northern hemisphere , claiming the title of the North Star during the Earth’s precession cycle for 26,000 years [11] .
Tau Hercules currently has a declination of 46 h 18 m 48 s , but due to the effects of the precession, Tau Hercules was the closest star to the North Heavenly Pole , visible to the naked eye from 7,400 BC . The next time the polar star of Tau Hercules will be in approximately 18,400 years [6] .
Other seven bright stars claiming the title of " Polar ":
- Vega ( Lira )
- Alderamine ( Cepheus )
- Gamma Cepheus ( Cepheus )
- Alpha Ursa Minor ( Ursa Minor )
- Swan Delta ( Swan )
- Kappa Dragon ( Dragon )
- Tuban ( Dragon )
In Chinese Astronomy
In Chinese astronomy, there is the expression 七公 ( Qī Gōng ), meaning the Seven Excellencies . It refers to asterism consisting of τ Hercules , 42 Hercules , φ Hercules , χ Hercules , ν¹ Bootes , μ¹ Bootes and δ Bootes [12] . Accordingly, τ Hercules herself is known as 七公 二 ( Qī Gōng èr , English the Second Star of Seven Excellencies (Second Star of Seven Excellencies) [13] .
Notes
- ↑ 1 2 3 4 5 6 7 8 (English) SIMBAD query result: tau Her - Pulsating variable Star , Center de Données astronomiques de Strasbourg , < http://simbad.u-strasbg.fr/simbad/sim-id ? Ident = Tau + Her & NbIdent = 1 & Radius = 2 & Radius.unit = arcmin & submit = submit + id >
- ↑ English entry database for t Herculis
- ↑ Perryman, MAC; Lindegren, L .; Kovalevsky, J. & Hoeg, E. (1997), "The Hipparcos Catalog", Astronomy & Astrophysics T. 323: L49 – L52
- ↑ From apparent magnitude and parallax
- ↑ 1 2 (English) Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished)
- ↑ 1 2 3 4 5 (English) Kaler, James B., TAU HER (Tau Herculis) , University of Illinois , < http://stars.astro.illinois.edu/sow/tauher.html >
- ↑ 1 2 Fitzpatrick, EL & Massa, D. (March 2005), " Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry ", The Astronomical Journal T. 129 (3): 1642– 1662 , DOI 10.1086 / 427855
- ↑ Smith, KC & Dworetsky, MM (1993), "Elemental Abundances in Normal Late B-Stars and Hgmn-Stars from Co-Added IUE Spectra - Part One - Iron Peak Elements", Astronomy and Astrophysics T. 274 (2): 335
- ↑ Royer, F .; Grenier, S .; Baylac, M.-O. & Gómez, AE (2002), " Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i in the northern hemisphere ", Astronomy and Astrophysics T. 393 (3): 897–911 , DOI 10.1051 / 0004-6361: 20020943
- ↑ Kurt Vonnegut. Constellations: Hercules 'the Strongman' . The BBC (British Broadcasting Corporation).
- ↑ Astronomy // Encyclopedia for children. - M .: Avanta + , 2007 .-- S. 269.
- ↑ (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) AEEA (Activities of Exhibition and Education in Astronomy) 天文 教育 資訊 網 2006 年 6 月 26 日