Stars (the 27 Nakṣatra) have no “planetary ruler” as the signs do. Planets and nakṣatra are related only for the sake of calculating daśās, and every daśā system relates the two differently. If you want to understand the 27 nakṣatras (Indian Fixed Stars) forget about these temporary correlations and instead focus on the deva (divinity) that rules the nakṣatra. The Nakṣatra are ruled not by planets by by devas. This is a foreign idea to westerners, so as westerners have gotten into Indian astrology and as Indian astrologers have been influenced by the same, the concept has become confused. If you read my book – 27 Stars 27 Gods, you can very clearly understand how each deva imparts specific characteristics to the nakṣatra he or she rules.