Would "सूरज एक तारा होता है" be correct?
In my opinion it is the "more correct" answer because the sun always has been and will always be a star (for a few billion more years anyway), hence "hota hai" is superior
But the Sun has never be a star and won't ever be. According to the Surya Siddhanta there is only one Sun in this universe which is giving the light and heat to Bhu mandala.
Yes, it would also be correct. In fact, this sentence would sound more natural as this sentence is a universal truth. (Native speaker here.)
"सूर्य एक तारा है" should be accepted
This is Hindi not Sanskrit
Does "Suraj tara hai" work" (without "ek")?
Yes. "सूरज (एक) तारा होता है" would work as well.
Nope. I find that sentence really weird and unnatural.
सूरज एक तारा है sounds perfect and natural.
Can any other native speaker comment here?
Does this sound natural to you?
सूरज एक तारा होता है।
सूरज एक तारा है sounds the most natural (generally, this sentence structure sounds more natural for universal truths). However, if we wish to use होता है then सूरज एक तारा होता है sounds more natural.
So सूरज तारा है is just a total no-go?
You may use it in conversations
But grammatically it is incomplete