16 Serpentis
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Serpens |
| Right ascension | 15h 36m 29.57498s |
| Declination | +10° 00′ 36.5574″ |
| Apparent magnitude (V) | 5.261 |
| Characteristics | |
| Spectral type | K0III: CN1 Ba0.7 Sr2 |
| U−B color index | +0.66 |
| B−V color index | +0.937 |
| Astrometry | |
| Radial velocity (Rv) | +2.94±0.13 km/s |
| Proper motion (μ) | RA: 41.881 mas/yr Dec.: −125.722 mas/yr |
| Parallax (π) | 14.3226±0.1100 mas |
| Distance | 228 ± 2 ly (69.8 ± 0.5 pc) |
| Orbit | |
| Period (P) | 5,324±19 d |
| Eccentricity (e) | 0.345±0.024 |
| Periastron epoch (T) | 44,090±53 |
| Argument of periastron (ω) (secondary) | 358±4° |
| Semi-amplitude (K1) (primary) | 3.86±0.09 km/s |
| Details | |
| 16 Ser A | |
| Mass | 1.70 M☉ |
| Radius | 8 R☉ |
| Luminosity | 42.7 L☉ |
| Surface gravity (log g) | 2.64±0.12 cgs |
| Temperature | 4,946±51 K |
| Metallicity [Fe/H] | −0.13±0.06 dex |
| Rotational velocity (v sin i) | 1.4 km/s |
| Age | 2.40 Gyr |
| Other designations | |
| 16 Ser, BD+10°2884, FK5 3226, GC 20981, HD 139195, HIP 76425, HR 5802, SAO 101640 | |
| Database references | |
| SIMBAD | data |
16 Serpentis is a binary star system in the Serpens Caput portion of the equatorial constellation of Serpens, located 228 light years from the Sun. It is visible to the naked eye as a fain, orange-hued star with an apparent visual magnitude of 5.261. The system is moving further from the Earth with a heliocentric radial velocity of +3 km/s.
The variable radial velocity of this star was discovered at Lick Observatory and was announced by J. H. Moore in 1924. It is a single-lined spectroscopic binary with an orbital period of 14.58 years and an eccentricity of 0.345. The visible component is an evolved giant star with a stellar classification of K0III: CN1 Ba0.7 Sr2. This is a mild barium star with the suffix notation above indicating associated abundance anomalies. The companion is a presumed white dwarf star that has already passed through its giant stage, during which time it enhanced the envelope of the companion with s-process elements. The pair form one of the widest barium star binaries known, which may account for the mildness of the barium anomaly.