ARICNS data Constellation Vulpecula | Magnitude 7.307 Apparent magnitude (V) 7.307 | |
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HD 190228 is a star located in the constellation Vulpecula. Its apparent magnitude is 7.31 and the absolute magnitude is 3.34. The distance is 201 light years from Earth. The star is definitely old with age over 10 billion years and it is metal-poor.
In 2000, it was announced that a giant planet was orbiting the star with a minimum mass of 5 Jupiter masses, designated HD 190228 b. The planetary nature of the object was questioned because of the low metal content of the star: giant planets are more likely to be found around high-metallicity stars, so it was argued that the object was more likely to be a brown dwarf. Later astrometric measurements confirmed this: HD 190228 b is in fact a brown dwarf of 49.4 Jupiter masses in a nearly face-on orbit. The brown dwarf takes 1146 days to orbit the star, and the orbit is elliptical with an eccentricity of 0.5.