Answer

Bhagwan Sambhavnath Swami’s Janma Nakshatra is Jyeshtha. A Jain source also notes that his Garbh Kalyanak occurred under Mrigshirsha Nakshatra. ( jainworld.jainworld.com)

Takeaway

If you mean the birth star, the answer is Jyeshtha Nakshatra. ( jainworld.jainworld.com)