HD 221420
HD 221420 (HR 8935; Gliese 4340) is a likely binary star system in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.81, allowing it to be faintly seen with the naked eye. The object is relatively close at a distance of 102 light years but is receding with a heliocentric radial velocity of 26.5 km/s.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 23h 33m 19.5789s |
| Declination | −77° 23′ 07.194″ |
| Apparent magnitude (V) | 5.81±0.01 |
| Characteristics | |
| Spectral type | G2 IV-V |
| U−B color index | +0.31 |
| B−V color index | +0.68 |
| Astrometry | |
| Radial velocity (Rv) | 26.48±0.02 km/s |
| Proper motion (μ) | RA: +16.306 mas/yr Dec.: +0.736 mas/yr |
| Parallax (π) | 32.1023 ± 0.0325 mas |
| Distance | 101.6 ± 0.1 ly (31.15 ± 0.03 pc) |
| Absolute magnitude (MV) | +3.33 |
| Details | |
| Mass | 1.35±0.01 M☉ |
| Radius | 1.95±0.01 R☉ |
| Luminosity | 4.01±1 L☉ |
| Surface gravity (log g) | 4.03±0.03 cgs |
| Temperature | 5,830±44 K |
| Metallicity [Fe/H] | +0.34±0.07 dex |
| Rotational velocity (v sin i) | 2.8±0.5 km/s |
| Age | 3.65±0.23 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 221420 has a stellar classification of G2 IV-V, indicating a solar analogue with a luminosity class intermediate between a subgiant and a main sequence star. The object is also extremely chromospherically inactive. It has a comparable mass to the Sun and a diameter of 1.95 R☉. It shines with a luminosity of 4 L☉ from its photosphere at an effective temperature of 5,830 K, giving a yellow glow. HD 221420 is younger than the Sun at 3.65 billion years. Despite this, the star is already beginning to evolve off the main sequence. Like most planetary hosts, HD 221420 has a metallicity over twice of that of the Sun and spins modestly with a projected rotational velocity 2.8 km/s.
There is a mid-M-dwarf star with a similar proper motion and parallax to HD 221420, which is likely gravitationally bound to it. The two stars are separated by 698 arcseconds, corresponding to a distance of 21,756 AU.