How to input equation like C^{*}, the asterisk can't put in right-up position correctly

[hitbuyi]

I write it as C^{*}, it doesn’t work, so how to write following equation in libreoffice

(ajlittoz changed tag writer to math because this is a problem with Math even is the formula is inserted into a Writer document)

[mikekaganski]

FAQ: How do I get * as a superscript? Using x^* produces an error

And also this other FAQ, too.