They are not created, they are formed by means of the natural laws from preexisting matter. This has nothing to do with yesh mai-ayin (creation from nothing) which occurred at the very beginning.
We usually talk of star formation in terms of the gas mass that is converted
into stars each year.
Indeed as Rashi and others point out on Bereishis 1:14 Yesh mai-ayin could have occurred only at the very beginning and that all other creations were formed upon the command of Hashem at the beginning of each day from the now existing primordial material..
And God said, "Let there be luminaries in the expanse of the heavens,
to separate between the day and between the night, and they shall be
for signs and for appointed seasons and for days and years.
As Rashi said
Let there be luminaries, etc.: They were created on the first day,
and on the fourth day, He commanded them to be suspended in the sky,
and likewise, all the creations of heaven and earth were created on
the first day, and each one was fixed in its proper place on the day
that was decreed upon it. That is why it is written:“with the heavens
(אֵת הַשָּׁמַיִם) to include their products,”and with the earth (וְאֵת
הָאָרֶץ)," to include its products. — [Gen. Rabbah 1:14]