HD 117440
HD 117440, also known by its Bayer designation d Centauri (d Cen), is a binary star in the constellation Centaurus. It is approximately 900 light years from Earth.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 13h 31m 02.66s[1] |
| Declination | −39° 24′ 26.3″[1] |
| Apparent magnitude (V) | +4.5/+4.7 |
| Characteristics | |
| Spectral type | G8III/G9III |
| U−B color index | +1.03 |
| B−V color index | +1.17 |
| Variable type | none |
| Astrometry | |
| Radial velocity (Rv) | −2 km/s |
| Proper motion (μ) | RA: -15.67 ± 0.47[1] mas/yr Dec.: -10.49 ± 0.31[1] mas/yr |
| Parallax (π) | 3.60 ± 0.49[1] mas |
| Distance | approx. 900 ly (approx. 280 pc) |
| Absolute magnitude (MV) | −3.4/−3.2 |
| Orbit[2] | |
| Period (P) | 83.14 ± 1.26 yr |
| Semi-major axis (a) | 0.161 ± 0.004″ |
| Eccentricity (e) | 0.521 ± 0.013 |
| Inclination (i) | 145.2 ± 4.0° |
| Longitude of the node (Ω) | 146.5 ± 8.6° |
| Periastron epoch (T) | B 1956.12 ± 1.91 |
| Argument of periastron (ω) (secondary) | 244.4 ± 3.6° |
| Other designations | |
| Database references | |
| SIMBAD | data |
Both components are yellow G-type giant stars. The primary, d Centauri A, has an apparent magnitude of +4.5, while the secondary, d Centauri B, has an apparent magnitude of +4.7. The two stars orbit around their common centre of mass once every 83 years and the secondary has a semi-major axis of 0.161 arcseconds.[2]
References
- 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. Vizier catalog entry
- "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 21 May 2017.
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