HD 128311 is a G-type main-sequence star located approximately 54 light-years away in the constellation Boötes. It is slightly less massive and less luminous than the Sun.
Properties
HD 128311 is classified as a G5V star, indicating a yellow dwarf star similar to our Sun, but slightly cooler and smaller. Its effective temperature is estimated to be around 5,500 Kelvin. The star's metallicity, which refers to the abundance of elements heavier than helium, is similar to that of the Sun.
Planetary System
HD 128311 is known to host at least two extrasolar planets: HD 128311 b and HD 128311 c.
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HD 128311 b: This planet is a gas giant with a mass estimated to be about 2.5 times that of Jupiter. It orbits the star at a distance of approximately 0.23 astronomical units (AU) with a period of around 449 days. This makes it a "hot Jupiter" type planet, albeit further from its star than many other hot Jupiters.
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HD 128311 c: This is another gas giant with a mass of about 3.2 times that of Jupiter. It orbits at a distance of approximately 1.1 AU from the star, with an orbital period of roughly 929 days.
The existence of these two planets makes HD 128311 a significant object of study in the search for and characterization of exoplanetary systems. The radial velocity method was used to detect the planets, which relies on measuring the "wobble" in the star's motion caused by the gravitational pull of the orbiting planets.
Observation
HD 128311 is not visible to the naked eye and requires a telescope for observation. Its coordinates are approximately Right Ascension 14h 35m 29.92s and Declination +09° 44′ 47.5″.