Psi Cygni
Star in the constellation Cygnus
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ψ Cygni, Latinised as Psi Cygni, is a triple star[3] system in the constellation called Cygnus. With a combined apparent visual magnitude of 4.92,[2] it is visible to the naked eye. As of 2002, the inner pair, components Aa and Ab, had an angular separation of 0.10 arc seconds along a position angle of 77.6°.[12] Their combined visual magnitude is 5.05.[3] Relative to this pair, the third member of the system, magnitude 7.61[3] component B, had an angular separation of 2.87 arc seconds along a position angle of 175.6° as of 2010.[13] Based upon an annual parallax shift of 11.59 mas,[1] Psi Cygni is located around 281 light years from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 55m 37.78622s[1] |
| Declination | +52° 26′ 20.2116″[1] |
| Apparent magnitude (V) | 4.92[2] (5.05 + 7.61)[3] |
| Characteristics | |
| A | |
| Spectral type | A4 Vn[4] |
| U−B color index | +0.05[2] |
| B−V color index | +0.13[2] |
| B | |
| Spectral type | F4 V[5] |
| Astrometry | |
| Radial velocity (Rv) | −10[6] km/s |
| Proper motion (μ) | RA: −37.62[1] mas/yr Dec.: −31.13[1] mas/yr |
| Parallax (π) | 11.59±0.38 mas[1] |
| Distance | 281 ± 9 ly (86 ± 3 pc) |
| Absolute magnitude (MV) | +0.23[7] |
| Orbit[8] | |
| Primary | Aa |
| Name | Ab |
| Period (P) | 54.08 yr |
| Semi-major axis (a) | 0.141″ |
| Eccentricity (e) | 0.484 |
| Inclination (i) | 112.0° |
| Details | |
| ψ Cyg Aa | |
| Luminosity | 62[9] L☉ |
| Temperature | 7,971[9] K |
| Rotational velocity (v sin i) | 207[4] km/s |
| ψ Cyg B | |
| Rotational velocity (v sin i) | 120[10] km/s |
| Other designations | |
| ψ Cyg, 24 Cygni, BD+52°2572, HD 189037, HIP 98055, HR 7619, SAO 32114, WDS 19556+5226.[11] | |
| Database references | |
| SIMBAD | data |
The brighter member of the system, presumably component Aa, displays the spectrum of an A-type main sequence star with a stellar classification of A4 Vn,[4] where the 'n' notation indicates "nebulous" absorption lines due to rapid rotation. It appears to be a spinning with a projected rotational velocity of 207.[4] The component is radiating 62 times the solar luminosity from its outer atmosphere at an effective temperature of 7,971 K.[9]