2 Cygni
Star in the constellation Cygnus
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2 Cygni is a blue-white hued star in the northern constellation of Cygnus, located a few degrees from Albireo. It is a probable astrometric binary;[10] the visible component can be viewed with the naked eye, having an apparent visual magnitude of 4.976.[2] Based upon an annual parallax shift of 3.6 mas,[1] it is located roughly 910 light years from Earth. It has a peculiar velocity of 23 km/s and may be a runaway star[5] system.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 24m 07.57863s[1] |
| Declination | +29° 37′ 16.7934″[1] |
| Apparent magnitude (V) | 4.976[2] |
| Characteristics | |
| Spectral type | B3 IV[3] |
| B−V color index | −0.117[2] |
| Astrometry | |
| Radial velocity (Rv) | −23.60±2.0[4] km/s |
| Proper motion (μ) | RA: +12.022[1] mas/yr Dec.: +12.173[1] mas/yr |
| Parallax (π) | 3.5657±0.1692 mas[1] |
| Distance | 910 ± 40 ly (280 ± 10 pc) |
| Absolute magnitude (MV) | −2.06[4] |
| Details | |
| Mass | 7.0±0.1[5] M☉ |
| Radius | 5.6[6] R☉ |
| Luminosity (bolometric) | 3,354[2] L☉ |
| Surface gravity (log g) | 3.653±0.035[7] cgs |
| Temperature | 16,479±219[7] K |
| Metallicity [Fe/H] | +0.03±0.05[8] dex |
| Rotational velocity (v sin i) | 137±8[7] km/s |
| Age | 36.6±0.5[5] Myr |
| Other designations | |
| BD+29°3584, FK5 3550, GC 26785, HD 182568, HIP 95372, HR 7372, SAO 87159[9] | |
| Database references | |
| SIMBAD | data |
The stellar classification of the primary is B3 IV,[3] matching a B-type subgiant star. It has seven[5] times the mass of the Sun and about 5.6[6] times the Sun's radius. The star is 37[5] million years old with a high rate of spin; it has a projected rotational velocity of 137 km/s.[7] It is radiating 3,354[2] times the Sun's luminosity from its photosphere at an effective temperature of 16,479 K.[7]
In 2024, imaging detected a candidate companion star at an angular separation of 70 mas. It appears to be a main sequence star with an estimated mass of 5.90±0.18 M☉.[11]