Question: What equation is this Indian astrophysicist who founded Indian Physical Society best known for?

full_context: Document 1: Maharashtra Sahitya Parishad: Maharashtra Sahitya Parishad is a literary institution situated in the West Indian state of Maharashtra for the purpose of the "furtherance of Marathi language and literature". It was set up in Pune in 1906. The Encyclopedia of Indian Literature considers it as Marathi's first representative literary body. The "Parishad" arranges annual conferences runs "Maharashtra Sahitya Patrika" a Marathi quarterly, provides a reference library, conducts qualifying examinations in Marathi language and literature and classes for non-Marathi speakers in Pune. It has undertaken the publishing a "History of Marathi literature". It has constituted various awards in the field of literature. The "Parishad" according to Deshpande lead in the demand for the formation of a separate linguistic state - Maharashtra.
Document 2: Indian Journal of Physics: The Indian Journal of Physics is a monthly peer-reviewed scientific journal published by Springer Science+Business Media on behalf of the Indian Association for the Cultivation of Science. It was established in 1926 by C. V. Raman and covers applied, experimental, and theoretical physics. The editor-in-chief is Subham Majumdar.
Document 3: Indian Physical Society: The Indian Physical Society is a professional society of physicists in India. It was formally established in 1934 by pioneering Indian physicist Meghnad Saha. The society's stated objectives are to promote the progress and uphold the cause of both pure and applied physics in India, to encourage publications in physics and related areas, to publisher books, journals, proceedings etc., to organize conferences, advise government bodies, and to secure and administer funds, grants and endowments for the furtherance of scientific research.
Document 4: Chandrasekhar family: The Chandrasekhar family is an Indian intellectual family. Several members of the family have achieved scientific distinction, notably in the field of physics. Two members of the family, Sir C. V. Raman and his nephew, Subrahmanyan Chandrasekhar, were Nobel laureates in physics.
Document 5: Chandrasekhar equation: In astrophysics, the Chandrasekhar equation is a dimensionless form of the Poisson equation for the density distribution of a spherically symmetric isothermal gas sphere subjected to its own gravitaional force, named after the Indian American astrophysicist Subrahmanyan Chandrasekhar. The equation reads
Document 6: Sadhan Basu: Sadhan Basu (1922–1992) was an Indian physical chemist, academic and the Palit Professor of Chemistry at the University of Calcutta. He was known for his elucidation of the Quantum Mechanical Model of Robert S. Mulliken and his article, "Degree of Polymerization and Chain Transfer in Methyl Methacrylate", co-authored by Jyotirindra Nath Sen and Santi R. Palit was the first published Indian article on polymer chemistry. He was an elected fellow of the Royal Society of Chemistry, Chemical Society of France, Indian Chemical Society, Indian National Science Academy and the Indian Academy of Sciences. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards, in 1962, for his contributions to chemical sciences.
Document 7: Institute of Public Enterprise: The Institute of Public Enterprise (IPE) was established in 1964 for the study of issues and policies relating to public enterprises (PEs). S S Khera, ICS, the Cabinet Secretary, Government of India, had conceived the idea of a research institution that would undertake a systematic and sustained study of issues relevant to the formulation of policies towards public enterprises. In the early sixties, when PEs were designed as the principal instrument to serve the social and economic objectives of development, Khera felt a need for an institute which would collect information on PEs, study issues and undertake consultancy and training for PEs.
Document 8: Meteoritical Society: The Meteoritical Society is a non-profit scholarly organization founded in 1933 to promote research and education in planetary science with emphasis on studies of meteorites and other extraterrestrial materials that further our understanding of the origin and history of the solar system.
Document 9: Indian Society of International Law: The Indian Society of International Law (ISIL) is an institution for the teaching, research and promotion of International Law in India. It is located opposite the Supreme Court of India and next to the Indian Law Institute (ILI). The ISIL was established in 1959 due to the efforts of V.K. Krishna Menon and was inaugurated by Prime Minister Jawahar Lal Nehru.
Document 10: Subrahmanyan Chandrasekhar: Subrahmanyan Chandrasekhar, FRS (Tamil: சுப்பிரமணியன் சந்திரசேகர் ; ; 19 October 1910 – 21 August 1995), was an Indian American astrophysicist who was awarded the 1983 Nobel Prize for Physics with William A. Fowler "for his theoretical studies of the physical processes of importance to the structure and evolution of the stars". His mathematical treatment of stellar evolution yielded many of the best current theoretical models of the later evolutionary stages of massive stars and black holes. The Chandrasekhar limit is named after him.
Document 11: Meghnad Saha: Meghnad Saha FRS (6 October 1893 – 16 February 1956) was an Indian astrophysicist best known for his development of the Saha ionization equation, used to describe chemical and physical conditions in stars. Saha was the first scientist to relate a star's spectrum to its temperature, developing thermal ionization equations that have been foundational in the fields of astrophysics and astrochemistry. He was repeatedly and unsuccessfully nominated for the Nobel Prize in Physics. Saha was also politically active and was elected in 1952 to India's parliament.
Document 12: National Physical Laboratory of India: The National Physical Laboratory of India, situated in New Delhi, is the measurement standards laboratory of India. It maintains standards of SI units in India and calibrates the national standards of weights and measures.
Document 13: Chandrasekhar limit: The Chandrasekhar limit ( ) is the maximum mass of a stable white dwarf star. The limit was first indicated in papers published by Wilhelm Anderson and E. C. Stoner, and was named after Subrahmanyan Chandrasekhar, the Indian astrophysicist who independently discovered and improved upon the accuracy of the calculation in 1930, at the age of 19, in India. This limit was initially ignored by the community of scientists because such a limit would logically require the existence of black holes, which were considered a scientific impossibility at the time. White dwarfs resist gravitational collapse primarily through electron degeneracy pressure. (By comparison, main sequence stars resist collapse through thermal pressure.) The Chandrasekhar limit is the mass above which electron degeneracy pressure in the star's core is insufficient to balance the star's own gravitational self-attraction. Consequently, white dwarfs with masses greater than the limit would be subject to further gravitational collapse, evolving into a different type of stellar remnant, such as a neutron star or black hole. (However, white dwarfs generally avoid this fate by exploding before they undergo collapse.) Those with masses under the limit remain stable as white dwarfs.
Document 14: Saha ionization equation: The Saha ionization equation, also known as the Saha–Langmuir equation, is an expression that relates the ionization state of an element to the temperature and pressure. The equation is a result of combining ideas of quantum mechanics and statistical mechanics and is used to explain the spectral classification of stars. The expression was developed by the Indian astrophysicist Meghnad Saha in 1920, and later (1923) by Irving Langmuir.
Document 15: Physics World: Physics World is the membership magazine of the Institute of Physics, one of the largest physical societies in the world. It is an international monthly magazine covering all areas of physics, pure and applied, and is aimed at physicists in research, industry, physics outreach, and education worldwide.
ground_truth: Saha ionization equation