Alef is a gas giant somewhat larger than Jupiter, but also rather less dense (it is nearly 40% larger than Jupiter, but has only some 75% of that planet'smass). It follows a very close orbit around the starTevel (HAT-P-9), so close indeed that completes a circuit of the star in less than four day. This proximity to its primarystar makes Alef one of the class of gas giants known as 'hot Jupiters'.
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