Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Octans |
Right ascension | 23h 33m 19.5789s[1] |
Declination | −77° 23′ 07.194″[1] |
Apparent magnitude (V) | 5.81±0.01[2] |
Characteristics | |
Spectral type | G2 IV-V[3] |
U−B color index | +0.31[4] |
B−V color index | +0.68[4] |
Astrometry | |
Radial velocity (Rv) | 26.48±0.02[5] km/s |
Proper motion (μ) | RA: +16.306 mas/yr[1] Dec.: +0.736 mas/yr[1] |
Parallax (π) | 32.1023 ± 0.0325 mas[1] |
Distance | 101.6 ± 0.1 ly (31.15 ± 0.03 pc) |
Absolute magnitude (MV) | +3.33[6] |
Details | |
Mass | 1.35±0.01[7] M☉ |
Radius | 1.95±0.01[7] R☉ |
Luminosity | 4.01±1[8] L☉ |
Surface gravity (log g) | 4.03±0.03[7] cgs |
Temperature | 5,830±44[9] K |
Metallicity [Fe/H] | +0.34±0.07[10] dex |
Rotational velocity (v sin i) | 2.8±0.5[11] km/s |
Age | 3.65±0.23[7] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
HD 221420 (HR 8935; Gliese 4340) is a likely binary star system[7] 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.
HD 221420 has a stellar classification of G2 IV-V,[3] indicating a solar analogue with a luminosity class intermediate between a subgiant and a main sequence star. The object is also extremely chromospherically inactive.[3] It has a comparable mass to the Sun and a diameter of 1.95 R☉.[7] It shines with a luminosity of 4 L☉[8] from its photosphere at an effective temperature of 5,830 K,[9] giving a yellow glow. HD 221420 is younger than the Sun at 3.65 billion years.[7] 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[7] and spins modestly with a projected rotational velocity 2.8 km/s.[11]
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.[7]
In a 2019 doppler spectroscopy survey, an exoplanet was discovered orbiting the star. The planet was originally thought to be a super Jupiter, having a minimum mass of 9.7 MJ.[9] However, later observations using Hipparcos and Gaia astrometry found it to be a brown dwarf with a high-inclination orbit,[7][10][14] revealing a true mass of 23 MJ.[7]
Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 22.9±2.2 MJ | 10.15+0.59 −0.38 |
27.62+2.45 −1.54 |
0.14+0.04 −0.03 |
164.0+1.9 −2.6° |
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