V509 Cassiopeiae
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 23h 00m 05.1s |
| Declination | +56° 56′ 43″ |
| Apparent magnitude (V) | +4.6 - +6.1 |
| Characteristics | |
| Spectral type | G0Ia0 (K5Ia0 - 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: −2.24 mas/yr Dec.: −2.60 mas/yr |
| Parallax (π) | 0.73 ± 0.25mas |
| Distance | 4,500ly (1,370pc) |
| Absolute magnitude (MV) | −8.6 (variable) |
| Details | |
| Mass | 11 M☉ |
| Radius | 400-900 R☉ |
| Luminosity | 200,000-400,000 L☉ |
| Temperature | 4,000-8,000 K |
| Metallicity [Fe/H] | 0.0 dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
V509 Cassiopeiae (V509 Cas or HR 8752) is a yellow hypergiant star in the constellation Cassiopeia.
HR 8752 is around 4,500 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.
HR 8752 is a naked eye star but it has no Bayer or Flamsteed designation, and is not recorded in other catalogues before the 19th century. When first recorded in the Radcliffe Observatory catalogue in 1840 it was 6th magnitude, and it is assumed it had been 6th magnitude or fainter before then. The star is slightly variable on a timescale of around a year, but the average brightness increased steadily, reaching magnitude 5.0 in the 1950s.
The brightness climbed to magnitude 4.75 by 1973, but the exact onset of this event was not well observed. Since then the star has been studied much more closely. It peaked at magnitude 4.6 in 1976, then dropped quickly to magnitude 4.9 by 1979, then oscillated between magnitudes 4.75 and 4.85 for the next decade. Since then the brightness has generally decreased, with somewhat irregular variations of less than a tenth of a magnitude, to magnitude 5.3 in 2000 and may have stabilised at that level.
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