What type of cable is used in most star networks physical medium?

Rj-45 is the most common type of cabling. RJ-45 refers to the terminator (connector) on the end of the cable, and the jack it plugs into--more specifically RJ-45M and RJ-45F, respectively. The associated cabling will be CAT(category)-5 or CAT-5e(enhanced), which are in the class of Unshielded Twisted Pair. A star network is typified by the hub or switch, with a cable running from it to every device on the network. Other cabling might be used, but CAT-5 is far and away most common.