Control height of subscript in LaTeX

Question

I have a problem with the following code

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
    \operatorname{P}_{\widehat{Y}} \quad \operatorname{P}_{Y} \\
\end{align*}
\end{document}

The subscripts are different heights, meaning that the bottom of the hatted Y is lower than the bottom of the vanilla Y. I would like to have their bottoms at the same height.

My ignorant theory is that the subscripts are aligned in the middle of the character and that the hat on the Y counts as an additional horizontal space occupied by my Y.

Ideally, I would like to have a fix that enables me to define a command that incorporates the fix and leaves the vanilla behaviour of the other subscripts in my document untouched.

Answer 1

You can use \smash to remove the extra vertical spacing, like so:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
    \operatorname{P}_{\widehat{Y}} \quad \operatorname{P}_{Y} \\
    \operatorname{P}_{\smash{\widehat{Y}}} \quad \operatorname{P}_{Y}
\end{align*}
\end{document}

By the way, when posting, please post a minimal working example so we can just cut and paste without having to add preambles, packages, \begin{document}, and so forth.

Answer 2

You could use a \vphantom, which makes an object with the height of its argument, but having no width.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
    \operatorname{P}_{\widehat{Y}} \quad \operatorname{P}_{Y\vphantom{\widehat{Y}}} 
\end{align*}
\end{document}