Hello Umang.

Yes, you can

There are two cases if you want to peruse aerospace engineering

Case:1

After completing your btech in mechanical/automobile engineering, continue your studies by doing masters in aerospace engineering

Case:2

There is other option while doing your btech you can study aerospace engineering by doingonline courses( in some websites like coursea).You will get paid/free certificate for the course.Which is usefull in future.

Thank you!

Definite you can do Masters in that but it's better you take mechanical as core.