All that can presently (March 2022) be gleaned about
Estelle Hart from sheet music covers and by Internet searching is that she was presumably an American actress/singer who has been featured on 2 works published in 1909.
Her portrait on the left is taken from
Shaky Eyes (1909) music by
Henry W. Armstrong, words by Billy Clark and published by
M. Witmark and Sons, New York, Chicago, San Francisco, USA.
Surfers are welcome to contribute any further information about this performer.