V509 Cassiopeiae
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 23h 00m 05.101221s |
| Declination | +56° 56′ 43.3509″ |
| Apparent magnitude (V) | +4.6 - +6.1 |
| Characteristics | |
| Spectral type | G4 0 (G0 - A6Ia+) |
| U−B color index | +1.33 |
| B−V color index | +1.0 - +1.7 |
| Variable type | SRd |
| Astrometry | |
| Radial velocity (Rv) | −50.20 km/s |
| Proper motion (μ) | RA: −3.013 mas/yr Dec.: −2.213 mas/yr |
| Parallax (π) | 0.2507±0.0633 mas |
| Distance | 11,000±400 ly (3,368±127 pc) |
| Absolute magnitude (MV) | −8.6 (variable) |
| Details | |
| Mass | 10.8 or 19.6 M☉ |
| Radius | 449±20 R☉ |
| Luminosity | 680,000+220,000 −210,000 L☉ |
| Temperature | 7,900 K |
| Metallicity [Fe/H] | 0.0 dex |
| Other designations | |
| HR 8752, HD 217476, FK5 3839, HIP 113561, SAO 35039, AAVSO 2255+56 | |
| Database references | |
| SIMBAD | data |
V509 Cassiopeiae (V509 Cas or HR 8752) is one of two yellow hypergiant stars found in the constellation Cassiopeia, which also contains Rho Cassiopeiae.
HR 8752 is around 11,000 light-years from Earth. It has an apparent magnitude that has varied from below +6 in historical times to a peak of +4.6 and now around +5.3 and is classified as a semiregular variable star of type SRd. It is undergoing strong mass loss as part of its rapid evolution and has recently passed partway through the yellow evolutionary void by ejecting around a solar mass of material in 20 years.
A hot main sequence companion (B1V) was described in 1978 on the basis of a colour excess in the ultraviolet.