HD 189733 b Totally Explained

Everything about Hd 189733 B totally explained

HD 189733 b is a hot Jupiter class gas giant planet that closely orbits the yellow dwarf star HD 189733 A. The planet was discovered on October 5, 2005 when astronomers in the United States observed the planet transiting across the face of the star. The mass of the planet is estimated to be 15% larger than Jupiter's; with the planet completing an orbit around its host star every 2.2 days. It is occasionally referred to as HD 189733 Ab to distinguish it from the red dwarf star HD 189733 B. The HD 189733 star system is 63 light years from Earth in the direction of the constellation Vulpecula.
This planet exhibits the largest photometric transit depth (amount of the parent star's light blocked) of any extrasolar planet so far observed, of approximately 3%. While transiting the system also clearly exhibits the Rossiter-McLaughlin effect. Due to its high mass and close orbit the parent star has a very large semi-amplitude (K), the "wobble" in the star's radial velocity, of 205 m/s. It and HD 209458 b were the first two planets to be directly spectroscopically observed.
Its Lambert sphere, Rayleigh-scattering atmosphere, is 1.5+/-.2 Rj: over 30% larger than its transit disc. Its albedo is greater than 0.14. The planet would appear deep blue to our eyes.
The apparent longitude of ascending node of its orbit is 16 degrees +/- 8 away from north-south in our sky.

Direct spectral observation

On February 21, 2007, NASA released news that the Spitzer Space Telescope had measured detailed spectra from both HD 189733 b and HD 209458 b. The release came simultaneously with the public release of a new issue of Nature containing the first publication on the spectroscopic observation of the other exoplanet, HD 209458 b. The findings on HD 189733 b will appear in an upcoming issue of the Astrophysical Journal Letters. The spectroscopic observations of HD 189733 b were led by Carl Grillmair of NASA's Spitzer Science Center.
On 22 October, a team of astrophysicists based in Zurich managed to "detect and monitor [its] visible light" using polarimetry, the first such success; and sent their findings to The Astrophysical Journal.
In mid January 2008, spectral observation using Rayleigh scattering model found that if molecular hydrogen exists, it would have an atmospheric pressure of 410 ± 30 mbar of 0.1564 solar radii. The Mie approximation model also found that there's a possible condensate in its atmosphere, magnesium silicate (MgSiO₃) with a particle size of approximately 10^-2 to 10^-1 μm. Using both models, the planet's temperature would be between 1340 to 1540 K.

First map of an extra-solar planet

In May 2007 NASA released a map of the surface temperature of HD 189733 b, performed by spectral observations through the Spitzer Space Telescope. This is the first map ever published of an extra-solar planet.

First evidence of water vapor and organic compounds

On July 11, 2007, a team lead by Giovanna Tinetti published the results of their observations using the Spitzer Space Telescope concluding there's solid evidence for significant amounts of water vapor in the planet's atmosphere. Follow-up observations made using the Hubble Space Telescope confirm the presence of water vapor and also the organic compound methane. It is currently unknown how the methane originated as the planet's high temperature (700°C, 1292°F) favors the formation of carbon monoxide instead.

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