Hello

After Mechanical Engineering, you can pursue Astrophysics. You can pursue Astrophysics in
Indian Institute of Astrophysics, Bangalore
Pune University

Candidates can take admission on the basis of scores in GATE, UGC-CSIR / NET exam for Junior  Research   Fellowship (JRF).

Kindly mention if you have any other query so we can help you.

Good Luck!