The scientist who proved that stars with mass less than 1.44 times the mass of the Sun end up as White Dwarfs when they die is Option 2: S. Chandrashekhar.

Subrahmanyan Chandrasekhar, often referred to as S. Chandrasekhar, was an Indian-American astrophysicist who made significant contributions to our understanding of stellar structure and evolution. In the early 1930s, he conducted groundbreaking research on the behavior of stars under extreme conditions, particularly focusing on the fate of massive stars.

Chandrasekhar`s work led to the development of the theory of stellar evolution and the concept of white dwarfs. In 1930, he derived a theoretical limit known as the Chandrasekhar limit. This limit states that when a star`s mass exceeds 1.44 times the mass of the Sun (known as the Chandrasekhar mass), it cannot support itself against gravitational collapse and will undergo a catastrophic event known as a Type II supernova.

However, Chandrasekhar also discovered that stars with mass below the Chandrasekhar limit would have a different fate. He showed that stars with masses lower than 1.44 solar masses would not undergo a supernova explosion but instead would evolve into a dense, compact stellar remnant called a white dwarf. A white dwarf is formed when a star exhausts its nuclear fuel and collapses under its own gravity, but electron degeneracy pressure halts further collapse, preventing a supernova.

Chandrasekhar`s work on white dwarfs and the Chandrasekhar limit earned him the Nobel Prize in Physics in 1983, which he shared with William A. Fowler. His discoveries laid the foundation for understanding the evolution and final stages of low- to medium-mass stars like our Sun.

To summarize, S. Chandrasekhar is the scientist who provided the theoretical framework and proof that stars with a mass less than 1.44 times that of the Sun end up as white dwarfs when they die. His work revolutionized our understanding of stellar evolution and compact objects, leaving an enduring impact on the field of astrophysics.