28 Vulpeculae
Star in the constellation Vulpecula
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28 Vulpeculae is a single[9] star in the northern constellation of Vulpecula. It lies approximately 560 light years away and is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 5.047.[2] The star is moving closer to the Sun with a heliocentric radial velocity of −23 km/s, and may come as close as 198 light-years in 5.9 million years.[5]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Vulpecula |
| Right ascension | 20h 38m 31.9139s[1] |
| Declination | +24° 06′ 57.4433″[1] |
| Apparent magnitude (V) | 5.05[2] |
| Characteristics | |
| Evolutionary stage | Subgiant |
| Spectral type | B5IV[3] |
| U−B color index | −0.53[4] |
| B−V color index | −0.14[4] |
| Astrometry | |
| Radial velocity (Rv) | −22.6±1.2[5] km/s |
| Proper motion (μ) | RA: 10.317±0.273[1] mas/yr Dec.: −6.940±0.253[1] mas/yr |
| Parallax (π) | 5.8740±0.1760 mas[1] |
| Distance | 560 ± 20 ly (170 ± 5 pc) |
| Absolute magnitude (MV) | −0.96[5] |
| Details | |
| Mass | 5.0[2] M☉ |
| Luminosity | 713[2] L☉ |
| Surface gravity (log g) | 3.77[6] cgs |
| Temperature | 15,200[2] K |
| Metallicity [Fe/H] | +0.02±0.04[6] dex |
| Rotational velocity (v sin i) | 285[7] km/s |
| Other designations | |
| 28 Vul, BD+23°4084, HD 196740, HIP 101868, HR 7894, SAO 88945[8] | |
| Database references | |
| SIMBAD | data |
This is a subgiant star with a spectral class of B5 IV,[3] indicating a hot massive star that has started to evolve away from the main sequence after exhausting it core hydrogen. It has been included in a list of the least variable stars observed with the Hipparcos satellite; its brightness varied by no more than 0.0005 magnitudes in the Hipparcos passband.[10] The star has five[2] times the mass of the Sun and is spinning rapidly with a projected rotational velocity of 285 km/s.[7] It is radiating 713 times the Sun's luminosity from its photosphere at an effective temperature of 15,200 K.[2]