56 Ursae Majoris
Star in the constellation Ursa Major
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56 Ursae Majoris (56 UMa) is a binary star in the constellation Ursa Major. At an apparent magnitude of 5.03, it is a faint star but visible to the naked eye depending on factors such as light pollution and eyesight. Parallax measurements derive a distance of 555 light-years.
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 11h 22m 49.58373s[1] |
| Declination | +43° 28′ 57.7267″[1] |
| Apparent magnitude (V) | 5.03[2] |
| Characteristics | |
| Spectral type | G7IIIBa0.3[3] |
| U−B color index | +0.82[4] |
| B−V color index | +1.02[4] |
| Astrometry | |
| Radial velocity (Rv) | 1.01±0.05[5] km/s |
| Proper motion (μ) | RA: −35.561 mas/yr[6] Dec.: −10.651 mas/yr[6] |
| Parallax (π) | 5.8813±0.0930 mas[6] |
| Distance | 555 ± 9 ly (170 ± 3 pc) |
| Orbit[7] | |
| Period (P) | 16,911+438 −401 days |
| Semi-major axis (a) | 22.9+1.0 −1.1 AU |
| Eccentricity (e) | 0.562+0.012 −0.012 |
| Inclination (i) | 68+3.6 −3.4° |
| Longitude of the node (Ω) | 60+3 −3° |
| Periastron epoch (T) | 2468401+432 −385 |
| Argument of periastron (ω) (secondary) | 286+2.3 −2.3° |
| Details[7] | |
| 56 UMa A | |
| Mass | 4.3±0.2 M☉ |
| Radius | 21.16±0.86[8] R☉ |
| Surface gravity (log g) | 2.30[8] cgs |
| Temperature | 4,917±34[8] K |
| Metallicity [Fe/H] | 0.05 dex |
| 56 UMa B | |
| Mass | 1.31+0.11 −0.12 M☉ |
| Other designations | |
| BD+44°2083, FK5 2908, HD 98839, HIP 55560, HR 4392, SAO 43719 | |
| Database references | |
| SIMBAD | data |
It is a single-lined spectroscopic binary with an orbital period of about 45 years.[5] The primary is an evolved giant star with a spectral class G7IIIBa0.3, a Barium star.[3] The companion star is likely a heavy neutron star born by a supernova that exploded around 100,000 years ago.[7]
