Omicron Serpentis
Star in the constellation Serpens
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Omicron Serpentis (ο Ser, ο Serpentis) is a solitary[12] star in the Serpens Cauda (tail) section of the equatorial constellation Serpens. Based upon an annual parallax shift of 18.83 mas as seen from Earth,[1] it is located around 173 light years from the Sun. The star is visible to the naked eye with a base apparent visual magnitude of +4.26.[2]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Serpens |
| Right ascension | 17h 41m 24.87286s[1] |
| Declination | −12° 52′ 31.1086″[1] |
| Apparent magnitude (V) | 4.26[2] |
| Characteristics | |
| Spectral type | A2 Va[3] |
| U−B color index | +0.08[2] |
| B−V color index | +0.07[2] |
| Variable type | δ Sct[4] |
| Astrometry | |
| Radial velocity (Rv) | −30.2±1.2[5] km/s |
| Proper motion (μ) | RA: −72.90[1] mas/yr Dec.: −55.55[1] mas/yr |
| Parallax (π) | 18.83±0.25 mas[1] |
| Distance | 173 ± 2 ly (53.1 ± 0.7 pc) |
| Absolute magnitude (MV) | +0.760[6] |
| Details | |
| Mass | 2.13[7] M☉ |
| Radius | 2.2[8] R☉ |
| Luminosity | 42.6[9] L☉ |
| Surface gravity (log g) | 3.82±0.14[7] cgs |
| Temperature | 8,972±305[7] K |
| Rotational velocity (v sin i) | 112.6±1.2[10] km/s |
| Age | 518[7] Myr |
| Other designations | |
| ο Ser, 56 Ser, BD−12°4808, FK5 3405, HD 160613, HIP 86565, HR 6581, SAO 160747.[11] | |
| Database references | |
| SIMBAD | data |
This is a white-hued A-type main sequence star with a stellar classification of A2 Va.[3] It is located on the lower instability strip[6] and is classified as a Delta Scuti type variable star. The apparent magnitude of the star varies in the range 4.26−4.27 with a period of 76 minutes, or 0.053 days.[6][13]
The star has an estimated 2.13[7] times the mass of the Sun and about 2.2[8] times the Sun's radius. It is about half a billion[7] years old and is spinning with a projected rotational velocity of 112.6 km/s.[10] Omicron Serpentis is radiating 42.6[9] times the solar luminosity from its photosphere at an effective temperature of 8,972 K.[7]
In 1909, the symbiotic nova[14] RT Serpentis appeared near Omicron, although it only reached a maximum magnitude of 10.[15]