It is named for the telescope that discovered it, a NASA spacecraft named Kepler that is designed to detect Earth-like planets by measuring small dips in the brightness of their host stars as the planets cross in front.

This process, known as the transit method, was used to note the presence of six planets in orbit around Kepler-11, of which Kepler-11d is the third from its star.

The transit causes the star's brightness to dim slightly and at a regular rate, a phenomenon that the Kepler satellite notes till future study can prove or disprove the existence of a planetary body.

[3] Metallicity has been observed to play a major role determining the type of planet a star forms.

This suggests that, unlike its sister planets Kepler-11b and Kepler-11c, which are closer to their host star, Kepler-11d has maintained a large (in volume) atmosphere that is most likely composed of hydrogen and helium.

[1] In fact, according to detailed formation calculations, all planets of the system require some amount of hydrogen/helium in order to match their observed radii.

The innermost planet, Kepler-11b, which likely lost all of its primordial light-element envelope, still requires a tenuous atmosphere (either made of steam or of gases sequestered in the heavy-element core) to account for its observed radius.