Largest Gas Giant Planet

Jupiter Narrowly missing the title of the biggest gas giant as it has yet to be confirmed if it is indeed a planet and not a brown dwarf, CT Cha b is pipped to the post by HAT-P-32b. This hot Jupiter, which almost weighs the same as its prototype at 94% of its mass, might not be the heaviest gas giant on the block but it is certainly the largest, swelling to a size twice that of our Solar System’s giant.

Orbiting its Sun-like or F-type star in the constellation of Andromeda on a slightly elliptical orbit, HAT-P-32b rests some 1,044 light years away from Earth and was uncovered with the help of the six-telescope HATNet Project, an organisation in search of planets passing across their parent stars. While the team of astronomers that scrutinised HAT-P-32’s data were sure that they had hit on the existence of a great gas giant, confirming it proved to be tricky with high levels of jitter dominating the measurements and scuppering any chances of certainty in finding an exoplanet around the star.

It was not until spectra collected using the High Resolution Echelle Spectrometer (HIRES) at WM Keck Observatory in Hawaii could astronomers lock down the radial velocity of HAT-P-32, later concluding that the shake of what they assumed was the presence of an undiscovered planet, was in fact rambunctious stellar activity.

Determined not to give up on the existence of the then elusive HAT-P-32b, astronomers employed the KeplerCam CCD instrument at the Keck observatories to snap photometric observations, constructing the light curve which would soon reveal the shy gas giant as it passed across its star with the help of extensive analysis using the Blendanal program.

Although some might argue that HAT-P-32’s jitter could be the result of a dimmer secondary companion tangoing with the star in a binary, the existence of a planet around the metal-poor star was confirmed. While HAT-P-32 might be younger than our Sun at an age of 3.8 billion years, it is also larger, heftier and hotter, emitting nearly three times the amount of energy our star does.