SELECT "Replaced by" FROM table_45757 WHERE "Date of vacancy" = '23 february 2009'
What is Replaced By, when Date of Vacancy is '23 February 2009'?
CREATE TABLE table_45757 (
    "Team" text,
    "Outgoing manager" text,
    "Manner of departure" text,
    "Date of vacancy" text,
    "Replaced by" text,
    "Date of appointment" text
)