HD 154556
HD 154556, also known as HR 6357, is a solitary orange-hued star located in the southern circumpolar constellation Apus. It has an apparent magnitude of 6.21, placing it near the limit for naked eye visibility. The star is located relatively close at a distance of 228 light years based on Gaia DR3 parallax measurements, but it is drifter closer with a heliocentric radial velocity of −24 km/s. At its current distance, HD 154556's brightness is diminished by 0.26 magnitudes due to interstellar dust. It has an absolute magnitude of +2.10.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Apus |
| Right ascension | 17h 12m 19.93421s |
| Declination | −70° 43′ 15.8963″ |
| Apparent magnitude (V) | 6.21±0.01 |
| Characteristics | |
| Evolutionary stage | subgiant |
| Spectral type | K1 IV CN3 |
| U−B color index | +1.04 |
| B−V color index | +1.06 |
| Astrometry | |
| Radial velocity (Rv) | −24±0.4 km/s |
| Proper motion (μ) | RA: +49.060 mas/yr Dec.: −78.104 mas/yr |
| Parallax (π) | 14.3386 ± 0.0224 mas |
| Distance | 227.5 ± 0.4 ly (69.7 ± 0.1 pc) |
| Absolute magnitude (MV) | +2.10 |
| Details | |
| Mass | 1.25 M☉ |
| Radius | 6.35±0.32 R☉ |
| Luminosity | 19.7±0.1 L☉ |
| Surface gravity (log g) | 2.90±0.25 cgs |
| Temperature | 4,677 K |
| Metallicity [Fe/H] | +0.04±0.09 dex |
| Rotational velocity (v sin i) | <1 km/s |
| Age | 3.52+0.36 −0.37 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 154556 has a stellar classification of K1 IV CN3, indicating that it is an evolved K-type subgiant with a moderate abundance of cyano radicals in its spectrum, making it a CN star. It has 1.25 times the mass of the Sun and is calculated to be 3.52 billion years old, having expanded to 6.35 times the radius of the Sun. It now radiates 19.7 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,677 K. It has a near solar metallicity and spins slowly with a projected rotational velocity lower than 1 km/s.