Delta¹ Tauri (δ¹ Tauri, abbreviated Delta¹ Tau, δ¹ Tau) is a double star in the zodiac constellation of Taurus. Based upon an annual parallax shift of 20.96 mas as seen from Earth,[1] it is located roughly 156 light-years distant from the Sun. The system is faintly visible to the naked eye with a combined apparent visual magnitude of +3.772.[2] It is considered a member of the Hyades cluster.[7]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04h 22m 56.09253s[1] |
| Declination | +17° 32′ 33.0487″[1] |
| Apparent magnitude (V) | +3.772[2] (3.90 + 9.50)[3] |
| Characteristics | |
| Spectral type | G9.5 III CN0.5[4] |
| U−B color index | +0.801[2] |
| B−V color index | +0.919[2] |
| Astrometry | |
| Proper motion (μ) | RA: +106.56[1] mas/yr Dec.: −29.18[1] mas/yr |
| Parallax (π) | 20.96 ± 0.58 mas[1] |
| Distance | 156 ± 4 ly (48 ± 1 pc) |
| Absolute magnitude (MV) | +0.41[5] |
| Orbit[6] | |
| Period (P) | 529.8 d |
| Eccentricity (e) | 0.42 |
| Periastron epoch (T) | 2434356.5 JD |
| Argument of periastron (ω) (secondary) | 335° |
| Semi-amplitude (K1) (primary) | 3.0 km/s |
| Details[7] | |
| δ¹ Tau Aa | |
| Mass | 2.8±0.5 M☉ |
| Radius | 11.4 R☉ |
| Luminosity | 69 L☉ |
| Temperature | 5,000 K |
| Metallicity [Fe/H] | +0.10 dex |
| Rotation | 138.2 d |
| Rotational velocity (v sin i) | 4.2 km/s |
| Age | 620[8] Myr |
| δ¹ Tau Ab | |
| Mass | 1.28±0.1 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
The two constituents are designated δ¹ Tauri A and B. A is itself a binary star with components designated δ¹ Tauri Aa (officially named Secunda Hyadum /sɪˈkʌndə ˈhaɪədəm/, the traditional name for the entire system)[10] and Ab.
Nomenclature
editδ¹ Tauri (Latinised to Delta¹ Tauri) is the system's Bayer designation. The designations of the two constituents as Delta¹ Tauri A and B, and those of A's components - Delta¹ Tauri Aa and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[11]
The system bore the traditional name Hyadum II, which is Latin for "Second of the Hyades".[12] In 2016, the IAU organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[14] It approved the name Secunda Hyadum for the component Delta¹ Tauri Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[10]
In Chinese, 畢宿 (Bì Xiù), meaning Net, refers to an asterism consisting of δ¹ Tauri, Epsilon Tauri, Delta³ Tauri, Gamma Tauri, Alpha Tauri (Aldebaran), 71 Tauri and Lambda Tauri.[15] Consequently, the Chinese name for Delta¹ Tauri itself is 畢宿三 (Bì Xiù sān), "the Third Star of Net".[16]
Properties
editDelta¹ Tauri A is a single-lined spectroscopic binary with an orbital period of 529.8 days and an eccentricity of 0.42.[6] The visible member, component Aa, is an evolved G- or K-type giant star with a stellar classification of G9.5 III CN0.5.[4] The 'CN0.5' suffix indicates a mild overabundance of cyanogen in the outer atmosphere. It is chromospherically active and shows a radial velocity variation of 9.3±0.2 m/s with a period of 165±3 d.[7] The primary, component Aa, has 2.8 times the mass of the Sun, while the secondary, component Ab, has 1.3 times the Sun's mass.[7]
Delta¹ Tauri B is a magnitude 13.21 visual companion separated by 111.8 arcseconds from A.[3] It is most likely not physically related to the main star.[17]
References
edit- ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society, 172 (3): 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
- ^ a b Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
- ^ a b Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
- ^ Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics, 430 (1): 303–311, arXiv:astro-ph/0409683, Bibcode:2005A&A...430..303C, doi:10.1051/0004-6361:20041440, S2CID 12136256.
- ^ a b Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
- ^ a b c d Beck, P. G.; et al. (January 2015), "Detection of solar-like oscillations in the bright red giant stars γ Psc and θ1 Tau from a 190-day high-precision spectroscopic multisite campaign", Astronomy & Astrophysics, 573: 15, arXiv:1407.6352, Bibcode:2015A&A...573A.138B, doi:10.1051/0004-6361/201323019, S2CID 33898282, A138.
- ^ Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931.
- ^ "del01 Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-08.
{{cite web}}: CS1 maint: postscript (link) - ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
- ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
- ^ Kaler, James B., "Hyadum II", STARS, University of Illinois, retrieved 2017-08-09.
- ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
- ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
- ^ (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) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2008-10-25 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.