AO Cassiopeiae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 00h 17m 43.063s |
| Declination | +51° 25′ 59.12″ |
| Apparent magnitude (V) | 6.07-6.24 |
| Characteristics | |
| Spectral type | O8V((f)) + O9.2II |
| U−B color index | −0.97 |
| B−V color index | −0.13 |
| Variable type | Eclipsing Variable star |
| Astrometry | |
| Radial velocity (Rv) | −31.10 km/s |
| Proper motion (μ) | RA: −2.988 mas/yr Dec.: −2.374 mas/yr |
| Parallax (π) | 0.7546±0.0579 mas |
| Distance | 4,300 ± 300 ly (1,300 ± 100 pc) |
| Absolute magnitude (MV) | − |
| Orbit | |
| Period (P) | 3.52348 days |
| Semi-major axis (a) | 28.57 R☉ |
| Eccentricity (e) | 0 |
| Inclination (i) | 65.7° |
| Longitude of the node (Ω) | 3.10° |
| Semi-amplitude (K1) (primary) | 143.7 km/s |
| Semi-amplitude (K2) (secondary) | 230.6 km/s |
| Details | |
| II | |
| Mass | 9.65 M☉ |
| Radius | 9.43 R☉ |
| Luminosity | 115,000 L☉ |
| Surface gravity (log g) | 3.45 cgs |
| Temperature | 29,239 K |
| Rotational velocity (v sin i) | 120 km/s |
| V | |
| Mass | 15.59 M☉ |
| Radius | 4.61 R☉ |
| Luminosity | 66,000 L☉ |
| Surface gravity (log g) | 4.30 cgs |
| Temperature | 33,675 K |
| Rotational velocity (v sin i) | 130 km/s |
| Other designations | |
| Pearce's Star, AO Cas, HR 65, BD+50°46, HD 1337, SAO 21273, HIP 1415 | |
| Database references | |
| SIMBAD | data |
AO Cassiopeiae, also known as Pearce's Star, is a binary system composed of an O8 main sequence star and an O9.2 bright giant that respectively weigh anywhere between 20.30 and 57.75 times and 14.8 and 31.73 times the mass of the Sun.
The AO Cas system is an eclipsing binary with a period of roughly 3.5 days, with the apparent magnitude ranging between 6.07 and 6.24. Stars of this brightness are generally just visible to the unaided eye in dark skies in semirural locations. The component stars are so close to each other they are ellipsoidal (egg-shaped). AO Cas is considered a contact binary, with both stars at or near their Roche lobes.