Lambda Serpentis
Lambda Serpentis, Latinized from λ Serpentis, is a star in the constellation Serpens, in its head (Serpens Caput). It has an apparent visual magnitude of 4.43, making it visible to the naked eye. Based upon parallax measurements, this star lies at a distance of about 38.9 light-years (11.9 parsecs) from Earth. Lambda Serpentis is moving toward the Solar System with a radial velocity of 66.4 km s−1. In about 166,000 years, this system will make its closest approach of the Sun at a distance of 7.371 ± 0.258 light-years (2.260 ± 0.079 parsecs), before moving away thereafter.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Serpens |
| Right ascension | 15h 46m 26.61423s |
| Declination | +07° 21′ 11.0475″ |
| Apparent magnitude (V) | 4.43 |
| Characteristics | |
| Spectral type | G0 V |
| U−B color index | +0.11 |
| B−V color index | +0.60 |
| Variable type | Suspected |
| Astrometry | |
| Radial velocity (Rv) | −66.4 km/s |
| Proper motion (μ) | RA: −224.0±0.2 mas/yr Dec.: −69.8±0.3 mas/yr |
| Parallax (π) | 83.92 ± 0.15 mas |
| Distance | 38.87 ± 0.07 ly (11.92 ± 0.02 pc) |
| Absolute magnitude (MV) | 4.01 |
| Details | |
| Mass | 1.14 M☉ |
| Radius | 1.060±0.152 R☉ |
| Luminosity | 1.94 L☉ |
| Surface gravity (log g) | 4.09 cgs |
| Temperature | 5,884±4.4 K |
| Metallicity [Fe/H] | −0.03 dex |
| Rotational velocity (v sin i) | 3 km/s |
| Age | 3.8–6.7 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This star is 6% larger and 14% more massive than the Sun, although it has a similar stellar classification. It is shining with nearly double the Sun's luminosity and this energy is being radiated from the star's outer atmosphere at an effective temperature of 5,884 K. A periodicity of 1837 days (5.03 years) was suspected by Morbey & Griffith (1987), but it is probably bound to stellar activity. However, McDonald Observatory team has set limits to the presence of one or more exoplanets around Lambda Serpentis with masses between 0.16 and 2 Jupiter masses and average separations spanning between 0.05 and 5.2 Astronomical Units.