Specific instrumental effect occasionally used on Broadway

This is a verrrrrry random and specific question.

It doesn't appear too frequently but whenever I hear it I'm always thinking "what is that????" It's a very eerie ethereal tone, almost like a theremin? My best guess is it's just high strings but if anyone knows for sure or could elaborate on the technique I would love to know.

It can be heard in these two songs:

At 0:41 seconds

At 0:28 seconds

Love that you started this thread, Nowak. I certainly knew they were strings, but I didn't have a term to describe the effect other than "long-sustained-bell-like-tones".

There are especially great harmonics in the original orchestrations for "Bewitched".