Mu Lupi
Multiple star system in the constellation of Lupus
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Mu Lupi (μ Lup) is a system of three confirmed stars and one brown dwarf[3] in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 4.29[2] and lies roughly 340 light-years from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Lupus |
| Right ascension | 15h 18m 32.02296s[1] |
| Declination | −47° 52′ 30.9957″[1] |
| Apparent magnitude (V) | 4.29[2] |
| Characteristics | |
| Spectral type | B8 Ve (AB) + A2/3(V) (C)[3] |
| U−B color index | −0.41[2] |
| B−V color index | −0.03[2] |
| Astrometry | |
| Radial velocity (Rv) | +14.90±1.78[4] km/s |
| Proper motion (μ) | RA: −29.59[1] mas/yr Dec.: −35.07[1] mas/yr |
| Parallax (π) | 9.72±0.71 mas[1] |
| Distance | 340 ± 20 ly (103 ± 8 pc) |
| Absolute magnitude (MV) | −0.57[5] |
| Orbit[3] | |
| Primary | A |
| Name | B |
| Period (P) | 772 yr |
| Semi-major axis (a) | 1.657″ |
| Eccentricity (e) | 0.43 |
| Inclination (i) | 114.6° |
| Periastron epoch (T) | 2048 |
| Orbit[6] | |
| Primary | Ca |
| Name | Cb |
| Period (P) | 12.353±0.004 days |
| Eccentricity (e) | 0.4±0.1 |
| Periastron epoch (T) | 2,455,177.7 JD |
| Argument of periastron (ω) (primary) | 324±18° |
| Semi-amplitude (K1) (primary) | 2.4±0.4 km/s |
| Details[3] | |
| A | |
| Mass | 3.16 M☉ |
| Rotational velocity (v sin i) | 280 km/s |
| B | |
| Mass | 3.07 M☉ |
| Rotational velocity (v sin i) | 50 km/s |
| Ca | |
| Mass | 1.78 M☉ |
| Temperature | 8,500[6] K |
| Cb | |
| Mass | 0.05[6] M☉ |
| Other designations | |
| μ Lup, CD−47°9860, FK5 , HD 135734, HIP 74911, HR 5683, SAO 225638, WDS J15185-4753AB[7] | |
| Database references | |
| SIMBAD | data |
Two of the components of this system, A and B, form a pair with an angular separation of 1.657 arcseconds. An orbital solution gives an orbital period of 772 years. Component C, an A-type main-sequence star, lies at an angular separation of 23.3 arcseconds from the AB pair,[3] and is itself a binary with an orbital period of 12.35 days. Its companion has a mass of 0.05 M☉, too low to fuse hydrogen, and thus it is considered a brown dwarf.[6] A fifth component, not confirmed to be a physical companion, lies at an angular separation of 6.10 arcseconds from component AB, and with a mass of 0.05 M☉ is also a brown dwarf.[3]