Stellar System
HD 189733 A is an orange dwarf star of the spectral type K1.5V. The star has a mass of 82 percent that of the Sun, a radius 75 percent, and a luminosity of 26.4 percent. The star is between 89 and 102 percent as enriched in iron as the Sun, making the star more than 600 million years old.
The star has starspots which affect its luminosity by 1.5 percent in visible light. As a result, it is listed in the General Catalogue of Variable Stars as a BY Draconis variable with the variable star designation V452 Vul.
Discovered in 2006 by the infrared 2MASS astronomical survey, 2MASS J20004297+2242342 or HD 189733 B is a dim red dwarf star of spectral type M. The companion was observed at a separation of 216 astronomical units away from the primary star. Orbiting in a clockwise orbit (which is nearly perpendicular to the orbital plane of transiting planet HD 189733 b), the orbital period is estimated around 3,200 years long.
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