HAT-P-17 is a K-type main sequence star about 92.6 parsecs (302 ly) away. It has a mass of about 0.857 ± 0.039 M☉. It is the host of two planets, HAT-P-17b and HAT-P-17c, both discovered in 2010. A search for a binary companion star using adaptive optics at the MMT Observatory was negative.

In 2010, a multi-planet system consisting of a hot Saturn transiting in an eccentric orbit and a Jupiter-like planet in an outer orbit was detected. The transiting planet HAT-P-17b was detected by the HATNet Project using telescopes located in Hawaii, Arizona and at the Wise Observatory in Israel.

It was confirmed with radial velocity measurements taken on the Keck telescope, which also led to the discovery of the second planet in a much wider orbit. In 2013, radial velocity measurements of the Rossiter-McLaughlin effect showed that the projected angle in the sky between the stellar axis of rotation and the orbit of planet b was about 19°.


Observations of HAT-P-17b

Collaborative projects