HD 4778
Star in the constellation Andromeda
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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.[11] The star is located 350 light years away, as determined from its annual parallax shift of 9.62 mas.[3]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda[2] |
| Right ascension | 00h 50m 18.26532s[3] |
| Declination | +45° 00′ 08.1355″[3] |
| Apparent magnitude (V) | 6.13[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | A3VpSiSrCrEuKsn[4] |
| B−V color index | 0.043±0.004[2] |
| Variable type | α2 CVn[5] |
| Astrometry | |
| Radial velocity (Rv) | 1.60[6] km/s |
| Proper motion (μ) | RA: +65.570[3] mas/yr Dec.: +4.662[3] mas/yr |
| Parallax (π) | 9.6184±0.0488 mas[3] |
| Distance | 339 ± 2 ly (104.0 ± 0.5 pc) |
| Absolute magnitude (MV) | 1.18[7] |
| Details | |
| Mass | 2.24±0.09[7] M☉ |
| Radius | 2.36±0.12[8] R☉ |
| Luminosity | 34.9±4.3[8] L☉ |
| Surface gravity (log g) | 4.12±0.09[7] cgs |
| Temperature | 9,135±400[8] K |
| Rotation | 2.5616[7] days |
| Rotational velocity (v sin i) | 33[4] km/s |
| Age | 77[9] Myr |
| Other designations | |
| GO Andromedae, BD+44° 176, FK5 2055, HD 4778, HIP 3919, HR 234, SAO 36702, PPM 43369[10] | |
| Database references | |
| SIMBAD | data |
This is an Ap star with a stellar classification of A3VpSiSrCrEuKsn,[4] showing chemical peculiarities in its spectrum from strontium, chromium, and europium.[12] It is an Alpha2 Canum Venaticorum variable[5] with a magnetic field that varies across the range +1,400 to −1,100 G.[13] This rotation-modulated variability allows direct determination of the rotation rate of 2.5616 days.[7]
HD 4778 has 2.24[7] times the mass of the Sun and 2.36[8] times the Sun's radius. The star is radiating 35[8] times the Sun's luminosity from its photosphere at an effective temperature of 9,375 K.[7] It is about 77[9] million years old.