ἦ and ἆρα introduce questions asking merely for information and imply nothing as to the answer expected (neither yes nor
ἦ τέθνηκεν Οἰδίπου πατήρ; is Oedipus' father really
ἆρ' εἰμὶ μάντις;
a. ἆρα is from ἦ ἄρα. ἦ is chiefly poetic. Homer uses ἦ, not ἆρα. Both particles denote interest on the part of the questioner (often =
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].