Global InformationZeta Sagittae information
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagitta |
| Right ascension | 19h 48m 58.65978s[1] |
| Declination | +19° 08′ 31.3516″[1] |
| Apparent magnitude (V) | +5.00[2] (5.64 + 6.04 + 9.01)[3] |
| Characteristics | |
| Spectral type | A3 Vnn[4] (A1 V + A3 V)[5] |
| U−B color index | +0.06[2] |
| B−V color index | +0.10[2] |
| Astrometry | |
| Proper motion (μ) | RA: +17.63[1] mas/yr Dec.: +26.27[1] mas/yr |
| Parallax (π) | 12.79 ± 0.67 mas[1] |
| Distance | 260 ± 10 ly (78 ± 4 pc) |
| Absolute magnitude (MV) | +0.55[6] |
| Orbit[7] | |
| Period (P) | 8487.9±4.9 d |
| Semi-major axis (a) | 0.13605±0.00044″ |
| Eccentricity (e) | 0.7948±0.0019 |
| Inclination (i) | 132.33±0.41° |
| Longitude of the node (Ω) | 340.97±0.68° |
| Periastron epoch (T) | 44199.6±5.9 HMJD |
| Argument of periastron (ω) (secondary) | 355.3±1.0° |
| Details | |
| ζ Sge A | |
| Mass | 1.80[8] M☉ |
| Radius | 1.7[9] R☉ |
| Luminosity | 46[10] L☉ |
| Surface gravity (log g) | 3.89[8] cgs |
| Temperature | 8,422±286[8] K |
| Rotational velocity (v sin i) | 240[11] km/s |
| Age | 347[8] Myr |
| Other designations | |
ζ Sge, 8 Sge, BD+19°4229, GC 27431, HD 187362, HIP 97496, HR 7546, SAO 105298, PPM 137034, ADS 12973, WDS J19490+1909AB[12] | |
| Database references | |
| SIMBAD | data |
Zeta Sagittae (ζ Sagittae) is triple star[3] system in the northern constellation of Sagitta. It is visible to the naked eye, having a combined apparent visual magnitude of +5.00.[2] Based upon an annual parallax shift of 12.79 mas,[1] the distance to this star is approximately 260 light years.
The inner pair is a visual binary system consisting of two A-type main-sequence stars with an orbital period of 23.2 years (8,487.9 d), a semimajor axis of 0.136 arc seconds, and an eccentricity of 0.79.[7] The primary, component A, has a visual magnitude of 5.64[3] with a stellar classification of A3 Vnn,[4] where the 'nn' suffix indicates "nebulous" lines due to rotation. It is spinning rapidly with a projected rotational velocity of 240 km/s. This is giving the star an oblate shape with an equatorial bulge that is 14% larger than the polar radius.[11]
The secondary member, component B, is a magnitude 6.04 star, while the more distant component C is magnitude 9.01 and lies at an angular separation of 8.330 arc seconds from the other two.[3]
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