  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Vulpecula |
| Right ascension | 20h 44m 52.50423s [1] |
| Declination | 25° 16′ 14.2538″ [1] |
| Apparent magnitude (V) | 4.91 [2] |
| Characteristics | |
| Spectral type | K1 III [3] |
| U−B color index | +1.18 [2] |
| B−V color index | +1.19 [2] |
| Astrometry | |
| Radial velocity (Rv) | +30.00 [4] km/s |
| Proper motion (μ) | RA: −30.988 [1] mas/yr Dec.: −184.648 [1] mas/yr |
| Parallax (π) | 9.3255±0.1537 mas [1] |
| Distance | 350 ± 6 ly (107 ± 2 pc) |
| Absolute magnitude (MV) | −0.07 [5] |
| Orbit [6] | |
| Period (P) | 2,506±4 d |
| Eccentricity (e) | 0.383±0.023 |
| Periastron epoch (T) | 42511±29 MJD |
| Argument of periastron (ω) (secondary) | 272±5° |
| Semi-amplitude (K1) (primary) | 4.69±0.13 km/s |
| Details | |
| Mass | 1.55 [7] M☉ |
| Radius | 21.68+0.47 −0.63 [1] R☉ |
| Luminosity | 173.3±3.3 [1] L☉ |
| Surface gravity (log g) | 2.47 [8] cgs |
| Temperature | 4,498+67 −48 [1] K |
| Metallicity [Fe/H] | −0.10 [5] dex |
| Rotational velocity (v sin i) | 1.5 [9] km/s |
| Age | 4.20 [7] Gyr |
| Other designations | |
| 30 Vul, BD+24°4229, FK5 3657, GC 28920, HD 197752, HIP 102388, HR 7939, SAO 89084 [10] | |
| Database references | |
| SIMBAD | data |
30 Vulpeculae is a binary star system in the northern constellation of Vulpecula, located mid-way between Epsilon Cygni and a diamond-shaped asterism in Delphinus. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.91. [2] The system is located approximately 350 light years away from the Sun based on parallax, [1] and is drifting further away with a mean radial velocity of +30 km/s. [4] The system has a relatively high proper motion, traversing the celestial sphere at the rate of 0.186 arc seconds per annum. [11]
The variable radial velocity of this system was announced in 1922 by W. W. Campbell. It is a single-lined spectroscopic binary system with an orbital period of 6.86 years and an eccentricity of 0.38. The a sin i value is 149 ± 4 Gm (1.00 ± 0.03 AU ), where a is the semimajor axis and i is the orbital inclination. This provides a lower bound on the true semimajor axis. [6]
The visible component is an aging giant star with a stellar classification of K1 III [3] and an estimated age of 4.20 [7] billion years old. Having exhausted the supply of hydrogen at its core, the star has expanded to 22 [1] times the Sun's radius. It has 1.55 [7] times the mass of the Sun and is radiating 173 [1] times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,498 K. [1]
