January 7, 1999
Vol. 18 No. 7

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    [subrahmanyan chandrasekhar]  

    Chandrasekhar’s legacy continues with naming of new NASA telescope

    By Steve Koppes
    News Office

    NASA’s newest orbiting telescope, which will study X-rays produced by some of the most violent events in the universe, will carry the name of pioneering Chicago astrophysicist Subrahmanyan Chandrasekhar, NASA announced Dec. 21.

    A native of India, Chandrasekhar was known as Chandra to his friends and colleagues. He died in 1995 at the age of 84 after making major discoveries in astrophysics that spanned more than 60 years. All three of NASA’s Great Observatories, including the Hubble Space Telescope and the Compton Gamma Ray Observatory, are named for Chicago scientists.

    Chandrasekhar received the Nobel Prize in physics in 1983 for his studies of the physical processes important to the structure and evolution of stars. By applying the laws of physics to the universe, Chandrasekhar launched the field of astrophysics, said Michael Turner, the Bruce and Diana Rauner Distinguished Service Professor and Chairman of the Department of Astronomy & Astrophysics. “Following in Chandra’s path, astrophysicists today use the laws of physics to help understand how the universe began and might end, how stars are born, evolve and die, and the nature of the most interesting objects in the cosmos, including black holes and neutron stars,” Turner said.

    Chandrasekhar’s work on the mass limit of white dwarfs set the stage for understanding violent events in the evolution of stars, according to Peter Vandervoort, Professor in Astronomy & Astrophysics. “His work lays the foundation for the modern understanding of neutron stars and black holes that will come from the data collected by the Chandra Observatory.”

    Chandrasekhar’s contributions extend over an amazingly broad spectrum of astrophysical research, Vandervoort added. “He had an extraordinary intellect and the rarest kind of scientific integrity. He was a person apart in many respects. We were all in awe of him.”

    NASA plans to launch the Chandra Observatory no earlier than April 8 on the Space Shuttle Columbia. The Chandra Observatory, the most powerful X-ray observatory ever built, measures 45 feet long, weighs 5 tons and costs $1.3 billion. Scientists will use the observatory to examine X-rays emanating from incredibly dense, collapsed objects such as white dwarfs, neutron stars and matter falling into black holes.

    “Chandrasekhar’s work opened the door to the existence of collapsed objects, either neutron stars with diameters of about 10 miles or black holes with no physical surface but with characteristic dimensions of less than a mile,” said Eugene Parker, the S. Chandrasekhar Distinguished Service Professor Emeritus.

    At age 19 in 1930, Chandrasekhar formulated that when a star’s nuclear fuel is exhausted, it will remain a star in the form of a slowly cooling white dwarf about the size of Earth, only if the star’s mass is less than 1.4 times the mass of the sun.

    “If the mass of the star is greater than 1.4 solar masses, now called the Chandrasekhar limit, then the burned-out star cannot avoid falling in upon itself, vanishing from the realm of ordinary stars,” Parker explained. “There are many stars with masses far in excess of 1.4 solar masses, burning out in only a few million years because of their great luminosity. So there must be many stars that have suffered this fate.”

    NASA sponsored a naming contest for the observatory that attracted more than 6,000 entries. An independent panel selected two winners, who both wrote essays suggesting Chandra’s name: Mrs. Jatila van der Veen, a physics and astronomy teacher at Adolfo Camarillo High School in Camarillo, Calif., and Tyrel Johnson, a student at Priest River Lamanna High School in Laclede, Idaho.

    “That Chandra’s name might be nominated by a panel of elite scientists would not be surprising. But that it was put into nomination from the public, strongly so, is really quite surprising,” said Robert M. Wald, Professor in Physics. “Chandra himself did not promote his work or do anything to create a public relations image for it.”

    Chandrasekhar was more than just one of the century’s leading astrophysicists. His commitment to teaching was legendary. In the 1940s, he drove 200 miles round trip each week from Yerkes Observatory in Williams Bay, Wis., to the University to teach a class on stellar atmospheres. One day he insisted on driving from Yerkes to teach the class despite a heavy snowstorm. He ended up teaching a class of only two that day.

    The two students —Tsung Dao Lee and Chen Ning Yang—won the Nobel Prize in physics in 1957, obtaining the distinction even before their professor.

    “It was important to Chandra to be a teacher and ultimately a role model,” Vandervoort said. “He often said that as he got older, his colleagues did not, because he always seemed to be working with people at the beginning of their careers. He often joked that as a general rule he got along better with the children of his colleagues than with the colleagues themselves.”

    Chandrasekhar was born in Lahore, India, on Oct. 19, 1910. He received his B.A. from Madras University, India, in 1930 and his doctorate from Trinity College, Cambridge University, in 1933. He joined the Chicago faculty as a research associate in 1937. Chandrasekhar received the Morton D. Hull Distinguished Service Professorship in 1952.

    Chandrasekhar developed his own astonishing style of research that entailed tackling first one field of astrophysics and then another in great depth. He wrote more than half a dozen definitive books describing the results of his investigations on topics ranging from radiative transfer of energy through the atmospheres of stars to the motions of stars within galaxies, and from magnetohyrodynamics to Einstein’s theory of general relativity and black holes.

    Two of his colleagues in the Department of Astronomy & Astrophysics, Don Lamb and Robert Rosner, will be among the scientists who will conduct research with the Chandra Observatory. They and University research scientists Peter Freeman and Cole Miller also helped design and test the telescope’s data analysis software.

    Also involved was Vinay Kashyap, who received his doctorate in astronomy from the University. Kashyap now works at the Harvard-Smithsonian Center for Astrophysics, where he serves as a member of the Chandra Observatory science team.

    Lamb will use the Chandra Observatory to study the production of X-rays by compact stars, which is related both to Chandrasekhar’s earliest work and to some of his later work in general relativity and the mathematical properties of black holes. The telescope’s launch comes at an opportune time, Lamb said, because the study of X-ray bursts and other burst-like phenomena now is undergoing a period of great intellectual ferment.

    “The Chandra Observatory has wonderful capabilities for advancing our understanding of these incredibly energetic and violent phenomena,” he said.

    Rosner will use the Chandra Observatory to study X-ray emissions from stars to better understand the sun’s X-ray emissions. The research may help answer questions about the sun’s interaction with the Earth’s atmosphere during their youth and the possible biological effects of high levels of ionizing radiation during this epoch.

    NASA’s infrared telescope, which is still under construction, is the only Great Observatory that remains unnamed. These orbiting observatories will collect data from across most of the electromagnetic spectrum with multiple instruments over a period of years.

    The Hubble Space Telescope, launched in 1990, is named for Edwin Powell Hubble, who earned his bachelor’s degree at the University in 1910 and his doctorate in 1917. Hubble showed that galaxies besides our own existed in the universe, and that the universe is expanding. These findings form the cornerstone of the Big Bang theory of the universe’s origin and opened the field of cosmology.

    In 1991, the Compton Gamma Ray Observatory was named for Arthur Holly Compton, who served on the Chicago faculty from 1923 to 1945. Compton earned the 1927 Nobel Prize in physics for his scattering experiment, which demonstrated that light has characteristics of both a wave and a particle.

    Compton also made major contributions to the understanding of cosmic rays, particles that travel through space at velocities near the speed of light. During World War II, he directed the Metallurgical Laboratory at Chicago where Enrico Fermi and colleagues produced the first controlled nuclear chain reaction.

    “It’s an astounding and wonderful statement about the scientists who are a part of the University of Chicago’s history,” Lamb said. “It illustrates the incredibly strong and vital contributions that people here have made in astronomy and astrophysics over the last hundred years.”