HD 4778
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h 50m 18.26563s |
| Declination | +45° 00′ 08.1439″ |
| Apparent magnitude (V) | 6.13 |
| Characteristics | |
| Spectral type | A3VpSiSrCrEuKsn |
| B−V color index | 0.043±0.004 |
| Variable type | α2 CVn |
| Astrometry | |
| Radial velocity (Rv) | 1.60 km/s |
| Proper motion (μ) | RA: 65.353 mas/yr Dec.: 4.133 mas/yr |
| Parallax (π) | 9.3224±0.0916 mas |
| Distance | 350 ± 3 ly (107 ± 1 pc) |
| Absolute magnitude (MV) | 1.18 |
| Details | |
| Mass | 2.24±0.09 M☉ |
| Radius | 2.36±0.12 R☉ |
| Luminosity | 34.9±4.3 L☉ |
| Surface gravity (log g) | 4.12±0.09 cgs |
| Temperature | 9,135±400 K |
| Rotation | 2.5616 days |
| Rotational velocity (v sin i) | 33 km/s |
| Age | 77 Myr |
| Other designations | |
| GO Andromedae, BD+44° 176, FK5 2055, HD 4778, HIP 3919, HR 234, SAO 36702, PPM 43369 | |
| Database references | |
| SIMBAD | data |
HD 4778, also known as HR 234 and GO Andromedae, is a variable star in the constellation Andromeda. Its magnitude varies by 0.04 magnitudes from the median of 6.12 with a period of approximately 2.55 days. The star is located 350 light years away, as determined from its annual parallax shift of 9.32 mas.
This is an Ap star with a stellar classification of A3VpSiSrCrEuKsn, showing chemical peculiarities in its spectrum from strontium, chromium, and europium. It is an Alpha2 Canum Venaticorum variable with a magnetic field that varies across the range +1,400 to −1,100 G. This rotation-modulated variability allows direct determination of the rotation rate of 2.5616 days.
HD 4778 has 2.24 times the mass of the Sun and 2.36 times the Sun's radius. The star is radiating 35 times the Sun's luminosity from its photosphere at an effective temperature of 9,375 K. It is about 77 million years old.