Unlike conventional bulbs, fluorescent bulbs generate no heat. The socket on this bulb is a so-called G13 socket.
From Amazon
Osram Fluorescent Lamp Light Bulb L 15 Watt 840
Conrad Electronic
OSRAM Fluorescent tube EEC: G (A - G) G13 15 W Cool white Tube shape (Ø x L) 26 mm x 451.6 mm dimmable 1 pc(s)
OnBuy
Osram 0140-015840o#1 15w T8 Triphosphor Fluorescent tube Cool White (4000k) Lamps