1 Serpentis
1 Serpentis (1 Ser) is a red giant in the constellation Virgo with an apparent magnitude of 5.5. It is a red clump giant, a cool horizontal branch star that is fusing helium in its core. It has expanded to over 13 times the radius of the Sun and although it is cooler at 4,581 K it is 77 times more luminous. It is 322 light years away.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Virgo |
| Right ascension | 14h 57m 33.251s |
| Declination | −00° 10′ 03.40″ |
| Apparent magnitude (V) | 5.5 |
| Characteristics | |
| Evolutionary stage | Red clump |
| Spectral type | K1III |
| Astrometry | |
| Radial velocity (Rv) | 20.12 km/s |
| Proper motion (μ) | RA: +59.929 mas/yr Dec.: −26.500 mas/yr |
| Parallax (π) | 10.1280 ± 0.1010 mas |
| Distance | 322 ± 3 ly (98.7 ± 1.0 pc) |
| Absolute magnitude (MV) | +0.76 |
| Details | |
| Mass | 1.37 M☉ |
| Radius | 13.6 R☉ |
| Luminosity | 75 L☉ |
| Surface gravity (log g) | 2.5 cgs |
| Temperature | 4,581 K |
| Metallicity [Fe/H] | −0.07 dex |
| Rotational velocity (v sin i) | 3.4 km/s |
| Age | 4.58 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The Flamsteed designation 1 Serpentis was given to the star when the constellation Serpens was combined with the constellation Ophiuchus. It was also given the Bayer designation M Serpentis. When Ophiuchus and Serpens were separated into distinct constellations, 1 Serpentis was left over the border in Libra. Since then it has moved slightly and is now in Virgo.
A 10th-magnitude companion star discovered by William Herschel is 86″ away. It is at the same distance as 1 Ser and shares a common proper motion, It is considered likely to be a physical companion, with the two stars separated by 8,600 au. It has a spectral type of G5 IV, and it is slightly smaller and less luminous than the sun.
A much more widely-separated 10th-magnitude star is also listed in multiple star catalogues, but it is an unrelated background object.