Subrahmanyan Chandrasekhar (1910-1995), Indian-US astrophysicist, and his wife Lalitha. Chandrasekhar's main work was in showing that the fate of a star is dependent on its mass. He showed that a star like our Sun will collapse in on itself to form a white dwarf, whereas a star 1.4 times heavier than the Sun will form a super-dense neutron star. This boundary is known as the Chandrasekhar Limit. He was awarded the 1983 Nobel Prize in Physics for his work. Photographed at the McDonald Observatory, Texas, USA, in 1939.