description HD 189733 Overview
A K-type main-sequence star in Vulpecula whose hot Jupiter companion was the first exoplanet to have its atmospheric composition directly characterized.
insights Why this score
HD 189733 ranks #53 of 217 in the Star ranking, behind Achernar, ahead of Pollux.
Hot Jupiter atmosphere benchmark, nearby bright host, major exoplanet characterization reputation.
help HD 189733 FAQ
Why is the planet HD 189733 b famous for its blue color?
Visible-light observations indicate that HD 189733 b would appear deep blue, probably because silicate particles scatter light in its atmosphere. The color does not imply oceans because the planet is an intensely hot gas giant.
How close does HD 189733 b orbit its star?
The planet completes an orbit in only about 2.2 days. This extremely tight orbit makes it a hot Jupiter and raises its atmospheric temperature well above that of any Solar System giant planet.
What was first measured in the atmosphere of HD 189733 b?
The system became a landmark for direct study of an exoplanet's atmospheric composition. Observations have identified substances including water vapor and carbon-bearing molecules, although individual detections have been refined and debated over time.
Can amateur astronomers observe HD 189733 b transiting?
Experienced amateurs can record the transit as a small dip in the star's brightness using suitable photometric equipment. The host star lies in Vulpecula and is too faint for comfortable naked-eye viewing.
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