HD 15558
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 02h 32m 42.537s |
| Declination | 61° 27′ 21.57″ |
| Apparent magnitude (V) | 7.87 |
| Characteristics | |
| Spectral type | O4.5III(f) (O5.5III(f) + O7V) |
| U−B color index | −0.55 |
| B−V color index | +0.43 |
| V−R color index | +0.38 |
| R−I color index | +0.40 |
| J−H color index | +0.18 |
| Astrometry | |
| Radial velocity (Rv) | −45.10±1.50 km/s |
| Proper motion (μ) | RA: −0.478 mas/yr Dec.: −0.849 mas/yr |
| Parallax (π) | 0.5764±0.0662 mas |
| Distance | approx. 5,700 ly (approx. 1,700 pc) |
| Absolute magnitude (MV) | −0.79 |
| Orbit | |
| Period (P) | 442 days (1.2 yr) |
| Semi-major axis (a) | 726 R☉ |
| Eccentricity (e) | 0.37±0.07 |
| Argument of periastron (ω) (secondary) | 120° |
| Details | |
| Mass | >152±51 M☉ |
| Radius | 16.4 R☉ |
| Luminosity | ~660,000 L☉ |
| Surface gravity (log g) | 3.7 cgs |
| Temperature | 39,500 K |
| Age | 0.7-3 Myr |
| secondary | |
| Mass | 46±11 M☉ |
| Radius | 5.6 R☉ |
| Other designations | |
| HD 15558, HIP 11832, SAO 12326, IDS 02251+6101, TYC 4046-44-1, UBV 2530, GCRV 1424, 2MASS J02324253+6127215, WDS J02327+6127, PPM 13720, BD+60°502, GSC 04046-00044, CCDM J02327+6127, IC 1805 148 | |
| Database references | |
| SIMBAD | data |
HD 15558 (HIP 11832) is a massive O-type multiple star system in Cassiopeia and is specifically in our galaxy's Heart Nebula in the open cluster IC 1805. The primary is a very massive star with 152 M☉ and 660,000 L☉.