Delta1 Tauri

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δ1 Tauri
Taurus IAU.svg
Red circle.svg
Location of δ1 Tauri (circled)
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
δ1 Tau Aa
Mass 2.75 [7]   M☉
Radius 14.9 [7]   R☉
Luminosity 107 [7]   L☉
Surface gravity (log g)2.72 [8]   cgs
Temperature 4,819 [7]   K
Metallicity [Fe/H]+0.11 [8]   dex
Rotation 148.2 d [7]
Rotational velocity (v sin i)2.31 [9]  km/s
Age 588 [7]   Myr
δ1 Tau Ab
Mass 1.28±0.1  M☉
Other designations
Hyadum II, δ1 Tau, 61 Tauri, BD+17°712, FK5  162, HD  27697, HIP  20455, HR  1373, SAO  93897 [10]
Database references
SIMBAD data

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]

Contents

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 /sɪˈkʌndəˈhaɪədəm/ , the traditional name for the entire system) [11] and Ab.

Nomenclature

δ1 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). [12]

The system bore the traditional name Hyadum II, which is Latin for "Second of the Hyades". [13] In 2016, the IAU organized a Working Group on Star Names (WGSN) [14] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. [15] 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. [11]

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. [16] Consequently, the Chinese name for Delta1 Tauri itself is 畢宿三 (Bì Xiù sān), "the Third Star of Net". [17]

Properties

Delta1 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. The primary, component Aa, has 2.75 times the mass of the Sun, while the secondary, component Ab, has 1.3 times the Sun's mass. The primary star, at an age of 588 million years, is just evolving away from the horizontal branch on to the asymptotic giant branch after exhausting its core helium. [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. [18]

References

  1. 1 2 3 4 5 6 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.
  2. 1 2 3 4 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 .
  3. 1 2 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 .
  4. 1 2 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.
  5. ↑ 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.
  6. 1 2 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.
  7. 1 2 3 4 5 6 7 8 Schröder, K. -P.; Mittag, M.; Jack, D.; Rodríguez Jiménez, A.; Schmitt, J. H. M. M. (2020), "Magnetic activity and evolution of the four Hyades K giants", Monthly Notices of the Royal Astronomical Society, 492 (1): 1110, arXiv: 1912.03638 , Bibcode:2020MNRAS.492.1110S, doi: 10.1093/mnras/stz3476 .
  8. 1 2 Rosas-Portilla, F.; Jack, D.; Schröder, K. -P. (2024), "In pursuit of precise Ca II H&K chromospheric surface fluxes: A gravity and temperature dependence", Astronomy and Astrophysics, 692, Bibcode:2024A&A...692A.189R, doi:10.1051/0004-6361/202450691.
  9. ↑ 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.
  10. ↑ "del01 Tau", SIMBAD , Centre de données astronomiques de Strasbourg , retrieved 2017-08-08.
  11. 1 2 "Naming Stars". IAU.org. Retrieved 16 December 2017.
  12. ↑ 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].
  13. ↑ Kaler, James B., "Hyadum II", STARS, University of Illinois , retrieved 2017-08-09.
  14. ↑ "IAU Working Group on Star Names (WGSN)" . Retrieved 22 May 2016.
  15. ↑ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  16. ↑ (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.
  17. ↑ (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.
  18. ↑ 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.
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