Английская Википедия:HD 221420

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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 Шаблон:Val.

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 Шаблон:Val. It shines with a luminosity of Шаблон:Val from its photosphere at an effective temperature of Шаблон:Val, 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 Шаблон:Val.

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 Шаблон:Val.

Planetary system

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 Шаблон:Val. However, later observations using Hipparcos and Gaia astrometry found it to be a brown dwarf with a high-inclination orbit, revealing a true mass of Шаблон:Val.