Upsilon2 Centauri
Binary star system in the constellation Centaurus
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Upsilon2 Centauri is a binary star[6] system in the southern constellation Centaurus. Its name is a Bayer designation that is Latinized from υ2 Centauri, and abbreviated Upsilon2 Cen or υ2 Cen. This system is visible to the naked eye as a point of light with a combined apparent visual magnitude of +4.33.[2] Based upon an annual parallax shift of 2.57 mas as seen from Earth,[1] this star is located roughly 1,300 light years from the Sun. Relative to its neighbors, the system has a peculiar velocity of 39.2+8.8
−15.2 km/s and it may form a runaway star system.[9]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 14h 01m 43.49909 s[1] |
| Declination | −45° 36′ 12.2767″[1] |
| Apparent magnitude (V) | +4.33[2] |
| Characteristics | |
| Spectral type | F7 II/III[3] |
| U−B color index | +0.26[2] |
| B−V color index | +0.61[2] |
| Variable type | None[4] |
| Astrometry | |
| Radial velocity (Rv) | −7.8±7.4[5] km/s |
| Proper motion (μ) | RA: +8.64±1.09 mas/yr[1] Dec.: −16.25±0.88 mas/yr[1] |
| Parallax (π) | 2.57±1.05 mas[1] |
| Distance | approx. 1,300 ly (approx. 400 pc) |
| Absolute magnitude (MV) | −3.51[4] |
| Orbit[6] | |
| Period (P) | 207.357 d |
| Eccentricity (e) | 0.55 |
| Periastron epoch (T) | 2423880.5 JD |
| Argument of periastron (ω) (secondary) | 88° |
| Semi-amplitude (K1) (primary) | 12.7 km/s |
| Details | |
| Mass | 6.86±0.39[7] M☉ |
| Luminosity (bolometric) | 3,919[7] L☉ |
| Surface gravity (log g) | 2.00[8] cgs |
| Temperature | 6,495[7] K |
| Rotational velocity (v sin i) | 0.0[8] km/s |
| Age | 45.9±4.0[9] Myr |
| Other designations | |
| υ2 Cen, CD−44°9040, GC 18939, HD 122223, HIP 68523, HR 5260, SAO 224621[10] | |
| Database references | |
| SIMBAD | data |
This is a single-lined spectroscopic binary star system with an orbital period of 207.357 days and an eccentricity of 0.55.[6] The primary component has the spectrum of an evolved F-type giant/bright giant hybrid with a stellar classification of F7 II/III.[3] It is around 46[9] million years old with 6.9 times the mass of the Sun. The star is radiating 3,919 times the Sun's luminosity from its photosphere at an effective temperature of 6,495 K.[7]