How to add an asterisk symbol in a mathematical expression?

Question

I\'m trying to annotate a plot with R² value and significance coding, but I can\'t pass * as a symbol and not as the juxtaposition operator.

I\'ve tried

Answer 1

You need to use paste inside your expression:

text(4,6,expression(paste(R^2==8^"**")))

or

text(6,4,expression(paste(R^2==8, "**")))