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) | 4.64 + 5.03 [2] |
Characteristics | |
Spectral type | G7III + G9III [3] |
U−B color index | +1.03 |
B−V color index | +1.17 |
Variable type | Suspected |
Astrometry | |
Radial velocity (Rv) | −2.40±0.74 [4] 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 mas [1] |
Distance | approx. 900
ly (approx. 280 pc) |
Absolute magnitude (MV) | −3.4/−3.2 |
Orbit [5] | |
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) | 1956.12±1.91 B |
Argument of periastron (ω) (secondary) | 244.4±3.6° |
Details | |
Mass | 7.5±0.5 [6] M☉ |
Surface gravity (log g) | 1.86 [7] cgs |
Temperature | 4,683 [7] K |
Metallicity [Fe/H] | −0.36 [7] dex |
Rotational velocity (v sin i) | 4.5 [7] km/s |
Age | 40.3±7.6 [6] Myr |
Other designations | |
Database references | |
SIMBAD | data |
HD 117440, also known by its Bayer designation d Centauri, is a binary star [8] system in the southern constellation of Centaurus. It is visible to the naked eye with a combined apparent visual magnitude of 3.90. [9] The distance to this system is approximately 900 light years based on parallax measurements. [1] It is drifting closer to the Sun with a radial velocity of −2 km/s. [4]
A companion star was first reported by T. J. J. See in 1897 at an angular separation of 0.2 ″ from the primary. [2] Orbital elements for the pair were published by W. S. Finsen in 1962 [10] then updated in 1964, yielding an orbital period of 83.1 years with a semimajor axis of 0.161″ and an eccentricity of 0.52. [5] Both components are evolved G-type giant stars with a yellow, Sun-like hue. The primary, component A, has an apparent magnitude of +4.64, while the secondary, component B, has an apparent magnitude of +5.03. [10]