36 Ophiuchi
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Ophiuchus |
| Right ascension | A: 17h 15m 20.851s B: 17h 15m 20.978s C: 17h 16m 13.3624s |
| Declination | A: −26° 36′ 09.04″ B: −26° 36′ 10.18″ C: −26° 32′ 46.129″ |
| Apparent magnitude (V) | 5.08/5.08/6.34 |
| Characteristics | |
| Spectral type | K2 V/K1 V/K5 V |
| U−B color index | 0.51(AB)/1.04 |
| B−V color index | 0.86(AB)/1.15 |
| Variable type | C: RS CV |
| Astrometry | |
| Radial velocity (Rv) | -0.6/0.0/-1.6 km/s |
| Proper motion (μ) |
RA: -488.2/-473/-480.06 mas/yr Dec.: -1156.0/-1143/-1123.48 mas/yr |
| Parallax (π) | 167.1 ± 1.1mas |
| Distance | 19.5 ± 0.1 ly (5.98 ± 0.04 pc) |
| Orbit | |
| Companion | 36 Ophiuchi B |
| Period (P) | 568.9 yr |
| Semi-major axis (a) | 14.7″ |
| Eccentricity (e) | 0.922 |
| Inclination (i) | 99.6° |
| Longitude of the node (Ω) | -83.6° |
| Periastron epoch (T) | 1763.39 |
| Details | |
| 36 Oph A/B | |
| Mass | 0.85/0.85 M☉ |
| Radius | 0.817 ± 0.016/0.81 R☉ |
| Luminosity (bolometric) | 0.33/0.36 L☉ |
| Luminosity (visual, LV) | 0.28/0.27 L☉ |
| Temperature | 4,843 ± 134/4,985 ± 20 K |
| Metallicity | B: –0.31 ± 0.042dex |
| Metallicity [Fe/H] | A: –0.20 dex |
| Age | 0.6-1.8 Gyr |
| 36 Oph C | |
| Mass | 0.71 M☉ |
| Radius | 0.72 R☉ |
| Luminosity (bolometric) | 0.20 L☉ |
| Luminosity (visual, LV) | 0.09 L☉ |
| Temperature | 4,550 K |
| Metallicity | 46-100% Sun |
| Other designations | |
| Database references | |
| SIMBAD | AB |
| A | |
| B | |
| C | |
| Exoplanet Archive | A |
| B | |
| C | |
| ARICNS | A |
| B | |
| C | |
36 Ophiuchi is a triple star system 19.5 light years from Earth. It is in the constellation Ophiuchus.
The primary and secondary stars are nearly identical orange main sequence dwarfs of spectral type K2/K1; the tertiary star is an orange main sequence dwarf of spectral type K5.
Star C is separated from the A-B pair by 700 arc seconds, compared to a minimum of 4.6 arcsec for A-B, so its effect on the movements of the A-B pair is small. A and B have active chromospheres.
The McDonald Observatory team has set limits to the presence of one or more planets around 36 Ophiuchi A with masses between 0.13 and 5.4 Jupiter masses and average separations spanning between 0.05 and 5.2 astronomical units, although beyond 1.5 AU orbits are inherently unstable around either 36 Ophiuchi A or 36 Ophiuchi B.
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