Xi Tauri
Xi Tauri (ξ Tau, ξ Tauri) is a hierarchical quadruple system[5] in the constellation Taurus.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 03h 27m 10.151s[2] |
| Declination | +09° 43′ 57.63″[2] |
| Apparent magnitude (V) | 3.73 - 3.81[3] |
| Characteristics | |
| Spectral type | B9Vn + B9V + B5V + F5V[4] |
| Variable type | Algol[3] |
| Astrometry | |
| Proper motion (μ) | RA: 50.58±1.48[2] mas/yr Dec.: −39.54±1.40[2] mas/yr |
| Parallax (π) | 15.60 ± 1.04 mas[2] |
| Distance | 210 ± 10 ly (64 ± 4 pc) |
| Orbit[5] | |
| Primary | ξ Tau Aa |
| Companion | ξ Tau Ab |
| Period (P) | 7.146651±0.000010 d |
| Eccentricity (e) | 0.0±0.05 |
| Inclination (i) | 86.2±0.5° |
| Longitude of the node (Ω) | 350.5±4.0° |
| Periastron epoch (T) | JD 2448299.075±0.010 |
| Argument of periastron (ω) (secondary) | 90±10° |
| Semi-amplitude (K1) (primary) | 89.1±10.0 km/s |
| Orbit[5] | |
| Primary | ξ Tau Aa-Ab |
| Companion | ξ Tau B |
| Period (P) | 145.12±0.055 d |
| Semi-major axis (a) | 16.09±0.18 mas |
| Eccentricity (e) | 0.213±0.007 |
| Inclination (i) | 87.07±0.19° |
| Longitude of the node (Ω) | 328.63±0.38° |
| Periastron epoch (T) | JD 2453712.90±0.34 |
| Argument of periastron (ω) (secondary) | 163.07±0.13° |
| Semi-amplitude (K1) (primary) | 38.02±5.0 km/s |
| Details[5] | |
| ξ Tau Aa | |
| Mass | 2.29±0.91 M☉ |
| Radius | 2.0±0.2 R☉ |
| Surface gravity (log g) | 4.2 cgs |
| Temperature | 9,400±500 K |
| Rotational velocity (v sin i) | 33±2 km/s |
| ξ Tau Ab | |
| Mass | 2.20±0.78 M☉ |
| Radius | 1.5±0.2 R☉ |
| Surface gravity (log g) | 4.2 cgs |
| Temperature | 9,200±500 K |
| Rotational velocity (v sin i) | 34±2 km/s |
| ξ Tau B | |
| Mass | 3.08±1.24 M☉ |
| Surface gravity (log g) | 4.3±0.1 cgs |
| Temperature | 15,100±200 K |
| Rotational velocity (v sin i) | 246±10 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Xi Tauri is a spectroscopic and eclipsing quadruple star. It consists of three blue-white B-type main sequence stars and an F-type main sequence star. Two of the stars form an eclipsing binary system and revolve around each other once every 7.15 days. These in turn orbit the third star once every 145 days. The fourth star is a F star that orbits the other three stars in a roughly fifty-year period and has been resolved optically.[7] The brightest and most massive of the four stars is the "third" star, although the eclipsing pair have a greater combined mass and hence are generally considered to be the primary.[4]
The typical combined apparent magnitude of the system is +3.73, but because the stars eclipse one another during their orbits, it is classified as a variable star, and its brightness varies from magnitude +3.73 to +3.81. Xi Tauri is approximately 210 light years from Earth.[2]
Nomenclature for the four stars varies. Some sources refer to the faint resolved companion as component C, while others refer to it as B. Similarly, the inner three stars are respectively Aa, Ab, and B, or Aa, Ab, and Ac.[4][5]
References
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ 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.Vizier catalog entry
- ^ a b "Xi Tau". AAVSO. Retrieved 2022-07-17.
- ^ a b c Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5. S2CID 119047709.
- ^ a b c d e Nemravová, J. A.; et al. (2013). "An Unusual Quadruple System ξ Tauri". Central European Astrophysical Bulletin. 37 (1): 207–216. Bibcode:2013CEAB...37..207N.
- ^ "ksi Tau -- Star". SIMBAD Astronomical Database. Centre de données astronomiques de Strasbourg. Retrieved 2013-09-29.
- ^ Rica Romero, F. M. (2010). "Orbital elements for eight binaries. Study of the nature of wide components. I" (PDF). Revista Mexicana de Astronomía y Astrofísica. 46: 263–277. Bibcode:2010RMxAA..46..263R.