| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 38m 41.18316s[2] |
| Declination | +54° 58′ 25.6420″[2] |
| Apparent magnitude (V) | 5.889±0.015,[3] 6.37[4] |
| Characteristics | |
| Spectral type | F6V[5](F5 V + F5 V)[3] |
| B−Vcolor index | 0.482±0.004[5] |
| Variable type | Algol[4] |
| Astrometry | |
| Radial velocity (Rv) | −13.9±0.2[5] km/s |
| Proper motion (μ) | RA: +34.885[2]mas/yr Dec.: +162.839[2]mas/yr |
| Parallax (π) | 24.7090±0.0422 mas[2] |
| Distance | 132.0 ± 0.2 ly (40.47 ± 0.07 pc) |
| Absolute magnitude (MV) | 2.83[5] |
| Orbit[3] | |
| Period (P) | 7.64075217±0.00000051 d[6] |
| Semi-major axis (a) | 22.6950 AU |
| Eccentricity (e) | 0.5378±0.0003 |
| Inclination (i) | 87.0±1.0° |
| Argument of periastron (ω) (secondary) | 0.860±0.001° |
| Semi-amplitude (K1) (primary) | 88.02±0.05 km/s |
| Semi-amplitude (K2) (secondary) | 89.97±0.10 km/s |
| Details[3] | |
| V1143 Cyg A | |
| Mass | 1.356±0.003 M☉ |
| Radius | 1.339±0.023 R☉ |
| Luminosity | 2.83±0.2[7] L☉ |
| Surface gravity (log g) | 4.317±0.015 cgs |
| Temperature | 6,450±100 K |
| Metallicity[Fe/H] | 0.08 dex |
| Rotational velocity (v sin i) | 18±3[7] km/s |
| V1143 Cyg B | |
| Mass | 1.328±0.002 M☉ |
| Radius | 1.316±0.023 R☉ |
| Luminosity | 2.65±0.2[7] L☉ |
| Surface gravity (log g) | 4.323±0.015 cgs |
| Temperature | 6,400±100 K |
| Rotational velocity (v sin i) | 28±3[7] km/s |
| Other designations | |
| V1143 Cyg,HD 185912,HIP 96620,HR 7484,SAO 31850[8] | |
| Database references | |
| SIMBAD | data |
HR 7484 (V1143 Cyg) is abinary star system in the northernconstellation ofCygnus. It is dimly visible to the naked eye under good viewing conditions, having anapparent visual magnitude of 5.89.[3] Based upon an annualparallax shift of 24.71,[2] it is located 132 light years away. The system is moving closer with a heliocentricradial velocity of −14 km/s.[5]
Radial velocity measurements taken at theDominion Astrophysical Observatory inVictoria, British Columbia Canada in 1919 led to the determination byWilliam Edmund Harper that HR 7484 is a double-linedspectroscopic binary.[9] The next year he published an orbit with a period of 7.6383 days as compared to the modern value of 7.64075217 days.[10]
HR 7484 is a detachedeclipsing binary, which means theorbital plane is aligned close to the line-of-sight from the Earth, causing the components toeclipse twice per orbit.[11] The system is undergoingapsidal motion, with a rate greater than that predicted bygeneral relativity.[11] Both components are ordinaryF-type main-sequence stars with similar physical properties.[3] The star normally has an apparent magnitude of 5.89, but every 7.64 days (7 days, 15 hours, and 22 minutes) its brightness decreases to magnitude 6.37, approximately two thirds as bright. Five days and 17 hours after each primary eclipse, there is asecondary eclipse when the brightness drops to magnitude 6.06, about 85% of the normal brightness. Each eclipse lasts for 220 minutes.[4] Both eclipses arepartial.[7]
