36 Ursae Majoris
36 Ursae Majoris is a double star in the northern constellation of Ursa Major. With an apparent visual magnitude of 4.8, it can be seen with the naked eye in suitable dark skies. Based upon parallax measurements, this binary lies at a distance of 42 light-years (13 parsecs) from Earth.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Major |
| A | |
| Right ascension | 10h 30m 37.5793s |
| Declination | +55° 58′ 49.940″ |
| Apparent magnitude (V) | 4.82 |
| B | |
| Right ascension | 10h 30m 25.3089s |
| Declination | +55° 59′ 56.855″ |
| Apparent magnitude (V) | 8.86 |
| Characteristics | |
| A | |
| Evolutionary stage | main sequence |
| Spectral type | F8 V |
| U−B color index | −0.01 |
| B−V color index | +0.52 |
| B | |
| Evolutionary stage | main sequence |
| Spectral type | K7Ve |
| B−V color index | +1.34 |
| Astrometry | |
| A | |
| Radial velocity (Rv) | +8.57 km/s |
| Proper motion (μ) | RA: −177.045 mas/yr Dec.: −32.634 mas/yr |
| Parallax (π) | 77.2485 ± 0.0805 mas |
| Distance | 42.22 ± 0.04 ly (12.95 ± 0.01 pc) |
| Absolute magnitude (MV) | 4.29 |
| B | |
| Radial velocity (Rv) | +8.67 km/s |
| Proper motion (μ) | RA: −182.443 mas/yr Dec.: −32.034 mas/yr |
| Parallax (π) | 77.4072 ± 0.0182 mas |
| Distance | 42.135 ± 0.010 ly (12.919 ± 0.003 pc) |
| Absolute magnitude (MV) | 8.2 |
| Details | |
| A | |
| Mass | 1.10 M☉ |
| Radius | 1.17 R☉ |
| Luminosity | 1.69 L☉ |
| Surface gravity (log g) | 4.4.23 cgs |
| Temperature | 6,066 K |
| Metallicity [Fe/H] | −0.09 dex |
| Rotational velocity (v sin i) | 1.50 km/s |
| Age | 4.0 Gyr |
| B | |
| Mass | 0.626 M☉ |
| Radius | 0.648 R☉ |
| Luminosity | 0.10 L☉ |
| Surface gravity (log g) | 4.61 cgs |
| Temperature | 4,132 K |
| Metallicity [Fe/H] | −0.08 dex |
| Rotational velocity (v sin i) | 9 km/s |
| Age | 5 Gyr |
| Other designations | |
| A: BD+56°1459, FK5 394, HD 90839, HIP 51459, HR 4112, SAO 27670 | |
| B: BD+56°1458, HD 237903, SAO 27668 | |
| Database references | |
| SIMBAD | A |
| B | |
The brighter star of the two is a solar analog—meaning it has physical properties that make it similar to the Sun. It has 10% more mass and a radius 17% larger than the Sun, with an estimated age of four billion years. The spectrum of this star matches a stellar classification of F8 V, which indicates this is a main sequence star that is generating energy at its core through the nuclear fusion of hydrogen. The energy is being radiated into space from its outer envelope at an effective temperature of 6,066 K. This gives the star the characteristic yellow-white hue of an F-type star.
The fainter of the two stars has an apparent magnitude 8.86 and shares a common proper motion witIts spectral type of K7Ve indicates it is a red dwarf. Its has a mass 60% of the Sun's, a temperature of 4,132 K and a bolometric luminosity only 1% of the Sun's.
36 Ursae Majoris has a second companion with a magnitude of 11.44 located at an angular separation of 240.6″ along a position angle of 292°, as of 2004. It does not share the proper motion of the other two stars and is a more massive and luminous star but much further away.