Kappa Lupi
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Lupus |
| κ1 Lup | |
| Right ascension | 15h 11m 56.07286s |
| Declination | −48° 44′ 16.1692″ |
| Apparent magnitude (V) | 3.86 |
| κ2 Lup | |
| Right ascension | 15h 11m 57.67537s |
| Declination | −48° 44′ 37.2684″ |
| Apparent magnitude (V) | 5.70 |
| Characteristics | |
| κ1 Lup | |
| Spectral type | B9.5 Vne |
| U−B color index | −0.08 |
| B−V color index | −0.05 |
| κ2 Lup | |
| Evolutionary stage | main sequence |
| Spectral type | A3/5V |
| B−V color index | +0.144±0.008 |
| Astrometry | |
| κ1 Lup | |
| Radial velocity (Rv) | −6.6±2.9 km/s |
| Proper motion (μ) | RA: −96.50 mas/yr Dec.: −49.86 mas/yr |
| Parallax (π) | 18.12±0.47 mas |
| Distance | 180 ± 5 ly (55 ± 1 pc) |
| κ2 Lup | |
| Radial velocity (Rv) | +0.0±3.7 km/s |
| Proper motion (μ) | RA: −98.497 mas/yr Dec.: −43.645 mas/yr |
| Parallax (π) | 17.906 ± 0.0587 mas |
| Distance | 182.1 ± 0.6 ly (55.8 ± 0.2 pc) |
| Absolute magnitude (MV) | +1.84 |
| Details | |
| κ1 Lup | |
| Mass | 2.89±0.03 M☉ |
| Radius | 3.0 R☉ |
| Luminosity | 90 L☉ |
| Surface gravity (log g) | 3.99±0.14 cgs |
| Temperature | 10,280 K |
| Rotational velocity (v sin i) | 191±16 km/s |
| Age | 121 Myr |
| κ2 Lup | |
| Mass | 2.0 M☉ |
| Radius | 1.8 R☉ |
| Luminosity | 13 L☉ |
| Surface gravity (log g) | 4.26 cgs |
| Temperature | 8,255 K |
| Metallicity [Fe/H] | −0.01 dex |
| Rotational velocity (v sin i) | 160.4±1.0 km/s |
| Age | 653 Myr |
| Other designations | |
| κ1 Lup: CD−48°9704, FK5 1398, HD 134481, HIP 74376, HR 5646, SAO 225525 | |
| κ2 Lup: BD−48°9705, HD 134482, HIP 74380, HR 5647, SAO 225526 | |
| Database references | |
| SIMBAD | κ1 Lup |
| SIMBAD | κ2 Lup |
Kappa Lupi is a binary star in the constellation of Lupus. With a combined apparent magnitude of 3.70, it is visible to the naked eye. The average distance to this system, based on parallax measurements, is 180 light-years.
The stars in the system are separated by an angular separation of 26.44″. At their distance, this corresponds to a projected separation of 1,450 astronomical units. They are members of the Hyades Stream, which is a moving group that is coincident with the proper motions of the Hyades cluster.
The primary, Kappa1 Lupi, has an apparent magnitude of 3.86. It is a B-type main sequence star with a stellar classification of B9.5 Vne. The 'n' suffix indicates the spectrum shows "nebulous" absorption lines due to rapid rotation, while the 'e' means this is a Be star that displays Balmer series emission lines. With an estimated age of 195 million years, it is about 75% of the way through its life span on the main sequence. The star is rotating with a projected rotational velocity of 191 km/s. This rate of spin is giving the star an oblate shape with an equatorial bulge that is an estimated 9% larger than the polar radius.
The secondary, Kappa2 Lupi, has an apparent magnitude of 5.70. It is an A-type main-sequence star with a stellar classification of A3/5V. The star has a high rotation rate, showing a projected rotational velocity of 160 km/s. It is 2.0 times more massive and 1.8 times larger than the Sun, with 13 times the Sun's luminosity and an effective temperature of 8,255 K.
In Chinese astronomy, Kappa1 Lupi is called 騎陣將軍, Pinyin: Qízhènjiāngjūn, meaning Chariots and Cavalry General, because this star is marking itself and stand alone in Chariots and Cavalry General asterism, Root mansion (see : Chinese constellation).