From what I've read, the look back time is about 12.9 billion light years, and the current distance to the Earendel star is approximately 28 billion light years...
How close to us was it when it emitted the light Hubble is just now detecting?
What is the formula, if there is (a relatively simple) one, for calculating this? . . . .
P.S. EDIT: Web pages like The University of Tennessee at Knoxville's (UTK.edu) and Ned Wright's clearly show lookback (light travel) times, and current distances, but not distance at the time the star or whatever was shining at us....