Allan Sandage
Oxford Dictionary of Scientists:
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Allan Rex Sandage
American astronomer (1926–
Born in Iowa City, Sandage graduated from the University of Illinois in 1948 and obtained his PhD in 1953 from the California Institute of Technology. He was on the staff of the Hale Observatories at Mount Wilson and Mount Palomar from 1952 when he began as an assistant to Edwin Hubble. He was professor of physics at Johns Hopkins University (1987–88) and is now on the staff of the Carnegie Observatories, Pasadena.
In 1960, using the 200-inch (5-m) reflecting telescope, Sandage in collaboration with Thomas Matthews succeeded in making the first optical identification of a quasar or quasi-stellar object. Quasars first came to the notice of astronomers when a number of compact, rather than extended, radio sources were detected by the Cambridge surveys of the radio sky carried out in the 1950s. Sandage and Matthews showed that 3C–sp;48, a compact radio source discovered during the third Cambridge survey, was at the same position as a faint apparently starlike object. Sandage and others succeeded in obtaining spectra of 3C–sp;48 that were found to be quite unlike those of any other star. The mystery of these strange new objects was partially cleared up by Maarten Schmidt in 1963 when he showed that the spectral lines of a quasar have undergone an immense shift in wavelength.
Sandage continued to work on quasars and in 1965 introduced a method of identifying them by searching at an indicated radio position for objects emitting an excessive amount of ultraviolet or blue radiation. He found that many ultraviolet objects, which he named blue stellar objects or BSOs, were not radio emitters but could be still classed as quasars because they had the characteristic immense red shift first detected by Schmidt. He speculated that these might be older quasars that had passed beyond the radio phase of their life cycle. It is now known that the vast majority of quasars are not radio sources.
Gale Encyclopedia of Biography:
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Allan Rex Sandage
Astronomer Allan Rex Sandage (born 1926) took it as his life's work to find out how old and how large the universe is. His work led him to conclude the universe is 15 billion to 20 billion years old. Sandage is credited with the discovery of quasars, small blue cosmic objects that may be places where stars are born.
Became a Stargazer
Born on June 18, 1926, Sandage was an only child. His father was a business professor at Miami (Ohio) University and his mother was the daughter of the president of a Church of Jesus Christ of Latter Day Saints (Mormon) school. On quiet Ohio nights, Sandage enjoyed watching the stars through a friend's telescope. Soon he was keeping an eye on the skies day and night. As a teenager, he kept a record of sunspots he observed over a period of four years. Young Sandage read writings by British astronomer and mathematician Arthur Stanley Eddington and The Realm of the Nebulae (1936) by Edwin P. Hubble.
After studying physics and philosophy at Miami University, Sandage served in the U.S. Navy as an electronics specialist during World War II. After the war, he earned a bachelor's degree in physics from the University of Illinois in 1948 and a Ph.D. from the California Institute of Technology in 1953.
While still a student, Sandage worked at the Palomar Observatory with astronomers Hubble and Walter Baade, trying to discover the secrets of the universe through the world's largest telescope at that time. Sandage later used the 100-inch Hooker telescope on Mount Wilson and the 200-inch Hale telescope on Mount Palomar to uncover mysteries such as the evolution of stars.
Measured the Universe
In 1952, Sandage joined Carnegie Observatories, where he became involved in investigating the origins of the universe. During his first year, he equated the luminosity of the globular clusters M92 and M3 to the luminosity of the sun. He found that stars in those globular clusters were as much as 12 billion years old.
In September 1953, Hubble died of a heart attack. Sandage continued the painstaking work that Hubble had begun. He found that gathering data and eliminating errors were daunting tasks. Still, after much analysis, he found that Hubble's original estimates of the universe's age were more conservative than the data seemed to indicate. Sandage's results in 1958 seemed to show that the universe was 7 to 13 billion years old, much greater than Hubble had thought. By 1975, Sandage began to think the universe was even more ancient, perhaps 15 or 20 billion years old.
To determine the age of a star, Sandage looked at a classic color-magnitude diagram. He plotted the brightness of stars against their colors or temperatures. How bright a star is depends on its age, mass, and chemical makeup. Sandage looked at the relationships between stars that belong to younger clusters and stars that belong to older clusters to find clues to stellar evolution.
Working with Gustav Tammann, of the University of Basel, Switzerland, and Dr. Abijit Saha, of Kitt Peak National Observatory, Sandage found that the universe is expanding at a speed of about 55 kilometers/second/ megaparsec. This speed indicates that the universe is about 14 billion years old. Some stars have since been calculated to be about 15 billion years old, which bolsters Sandage's theory.
As an observational cosmologist, Sandage built on the work Hubble began in the 1920s and 1930s. Before long, Sandage was known as Mr. Cosmology, or the Super Hubble. Hubble-Sandage variable stars take their name from the energetic astronomer and his mentor.
Discovered Quasars
In 1964, Sandage and his colleague Thomas Matthews discovered sources of concentrated radio energy in distant space. They called them quasars, short for quasi stellar radio sources. The center of a quasar is thought to be a black hole that sucks in gases and other materials that form the discus shape associated with quasars. Quasars are very bright, probably about 1,000 times brighter than the Milky Way Galaxy. They are thought to be the most distant objects in the universe: in 1968 Maarten Schmidt found that they are located on the edge of the known universe.
Wrote on Religion
Unlike some scientists who see religion and science as opposed, Sandage believes they are complementary. In an article he wrote for Truth Journal, Sandage said science should take religion seriously and religion should respect science. "Science makes explicit the quite incredible natural order, the interconnections at many levels between the laws of physics, the chemical reactions in the biological processes of life, etc.," he wrote. "But science can answer only a fixed type of question. It is concerned with the what, when, and how. It does not, and indeed cannot, answer within its method (powerful as that method is), why."
Defended Theories
Observational cosmologists disagree on how to measure distances between Earth and the stars. Critics have often attacked Sandage's premise that the universe is always expanding, and others have questioned his findings. But time proved Sandage's measurements to have validity, even if they were not accepted at first by all his peers.
When Sandage and Tammann found that some scientists were selecting stars and galaxies that were too bright to represent "standard candles" - a measurement scientists use to determine distances between Earth and celestial objects - Sandage found new ways to take measurements. While critics ignored Sandage's findings, he and his team looked into Type 1A supernovas to correlate galactic rotational velocities with brightness.
Sandage's skirmishes with his colleagues and critics over the expansion rate of the universe were so heated at times that they were sometimes called the "Hubble Wars." Despite all the controversy over his work, Sandage was always regarded as one of the top observational cosmologists in the world.
Sandage's book Lonely Hearts of the Cosmos, was published in 1991. In retirement, Sandage lives in Pasadena, California, with his wife, Mary Lois. They have two sons, David and John.
Periodicals
Astronomy, December 1997.
Current Biography Yearbook, January 1999.
Online
"Allan Rex Sandage," The Bruce Medalists,http://www.physastro.sonoma.edu/BruceMedalists/Sandage/index.html (October 15, 2001).
"Allan Sandage," Carnegie Observatories,http://www.ociw.edu/research/sandage.html (October 15, 2001).
"Discovery of Quasars," Stellar,http://www.stellar.co.nz/tl19.html (October 15, 2001).
"Sandage, Allan R.," Biography.com,http://search.biography.com/print-record.pl?id=19167 (October 15, 2001).
"Sandage, Allan R.," Zoom Astronomy,http://www.allaboutspace.com/subjects/astronomy/glossary/indexs.shtml (October 15, 2001).
"A Scientist Reflects on Religious Belief," Origins: Truth Journal,http://www.origins.org/truth/1truth15.html (October 15, 2001).
"2000 Cosmology Prize Recipient: Allan R. Sandage," Peter Gruber Foundation,http://www.petergruberfoundation.org/sandage.htm (October 15, 2001).
Oxford Dictionary of American Quotation:
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Allan Sandage
(b.1926) The greatest mystery is why there is something instead of nothing, and the greatest something is this thing called life.(quoted in Alan Lightman and Roberta Brawer, Through a Window, 1990) [subject: Mysticism & Mystery]
Wikipedia on Answers.com:
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Allan Sandage
| Allan Sandage | |
|---|---|
 |
|
| Born | 18 June 1926 Iowa City, Iowa |
| Died | 13 November 2010 (age 84) San Gabriel, California |
| Nationality | United States |
| Fields | astronomy |
| Institutions | Carnegie Observatories |
| Alma mater | California Institute of Technology University of Illinois |
| Doctoral advisor | Walter Baade |
| Known for | cosmology |
| Influences | Walter Baade Edwin Hubble |
| Notable awards | National Medal of Science (1970) Bruce Medal (1975) Fellow of the Royal Society[1] |
Allan Rex Sandage FRS[1] (June 18, 1926 – November 13, 2010)[2][3][4][5] was an American astronomer. He was Staff Member Emeritus with the Carnegie Observatories in Pasadena, California.[6] He is best known for determining the first reasonably accurate value for the Hubble constant and the age of the universe.
| (96155) 1973 HA | 27 April 1973 |
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Contents
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Career
Sandage was one of the most influential astronomers of the 20th century.[7] He graduated from the University of Illinois in 1948. In 1953 he received a Ph.D. from the California Institute of Technology; the German-born Wilson Observatory-based astronomer Walter Baade was his advisor. During this time Sandage was a graduate student assistant to cosmologist Edwin Hubble. He continued Hubble's research program after Hubble died in 1953. In 1952 Baade had shaken the astronomical world by announcing[8] his determination of two separate populations of Cepheid variable stars in the Andromeda Galaxy, resulted in a doubling of the estimated age of the universe (from 1.8 to 3.6 billion years). Hubble had posited the earlier value; he had only considered the weaker Population II Cepheid variables as standard candles. Following Baade's pronouncements, Sandage showed that astronomers' previous assumption, that the brightest stars in galaxies were of approximately equal inherent intensity, was mistaken in the case of H II regions which he found not to be stars and inherently brighter than the brightest stars in distant galaxies. This resulted in another 1.5 factor increase in the calculated age of the universe, to approximately 5.5 billion years.[9] Throughout the 1950s and well into the 1980s Sandage was regarded as the pre-eminent observational cosmologist, making contributions to all aspects of the cosmological distance scale, ranging from calibrators within our own Milky Way Galaxy, to cosmologically distant galaxies.
Sandage began working at the Palomar Observatory. In 1958 he published[10] the first good estimate for the Hubble constant, revising Hubble's value of 250 down to 75 km/s/Mpc, which is close to today's accepted value. Later he became the chief advocate of an even lower value, around 50, corresponding to a Hubble age of around 20 billion years.
Sandage performed photometric studies of globular clusters, and calculated their age to be at least 25 billion years. This led him to speculate that the universe did not merely expand, but actually expanded and contracted with a period of 80 billion years. The current cosmological estimates of the age of the universe, in contrast, are typically of the order of 14 billion years. As part of his studies on the formation of galaxies in the early universe, he co-wrote the paper[11] now called ELS after the authors Olin J. Eggen, Donald Lynden-Bell and Sandage, first describing the collapse of a proto-galactic gas cloud into our present Milky Way Galaxy. He later defended the paper in 1990.[12]
In his 1961 paper "The Ability of the 200-inch Telescope to Discriminate Between Selected World Models,"[13] he suggested that the future of observational cosmology would be the search for two parameters: the Hubble constant H0 and the deceleration parameter q0. This paper influenced observational cosmology for at least three decades as it carefully laid out the types of observational tests that could be performed with a large telescope. He also published two atlases of galaxies, in 1961[14] and in 1981,[15] based on the Hubble classification scheme.
In 1962[16] Sandage studied the possibility of directly measuring the temporal variation of the redshift of extra-galactic sources. This analysis became known as the "Sandage–Loeb test".[17]
Sandage is noted for his discovery in the M82 galaxy of jets erupting from the core. These must have been caused by massive explosions in the core, and they have apparently been occurring for at least 1.5 million years.[18]
Sandage was a prolific researcher; during his career he published over 500 papers. Until his death he continued to be an active researcher at the Carnegie Observatories, still publishing several papers a year.[19]
Personal life
In 1959, Sandage married Mary Connelley, also an astronomer, with whom he had two sons, David and John.[5] Sandage became a Christian later in his life.[20] He wrote several essays on the subject of religion and science, which appeared in publications such as Science and the Spiritual Quest: New Essays by Leading Scientists (New York, NY: Routledge, 2002). On November 13, 2010, Sandage died of pancreatic cancer at his home in San Gabriel, California. He was 84 years old.[5]
Honors
Awards
- Helen B. Warner Prize for Astronomy (1957)
- Eddington Medal (1963)
- Gold Medal of the Royal Astronomical Society (1967)
- National Medal of Science (1970)
- Henry Norris Russell Lectureship (1972)
- Elliott Cresson Medal (1973)
- Fellow of the Royal Society[1]
- Bruce Medal (1975)
- Crafoord Prize (1991)
Named after him
- Main-belt asteroid, 9963 Sandage (1992 AN)
References
- ^ a b c Lynden-Bell, Donald; Schweizer, François (2012). "Allan Rex Sandage. 18 June 1926 -- 13 November 2010". Biographical Memoirs of Fellows of the Royal Society. doi:10.1098/rsbm.2011.0021.
- ^ Allan Sandage: Astronomer widely acknowledged as among the most outstanding of the 20th century, The Independent Obituary, 22 November 2010
- ^ Beich, Eugenie (15 November 2010). "Allan Sandage, surveyor of the cosmos, dies at 84". Nature. http://blogs.nature.com/news/thegreatbeyond/2010/11/allan_sandage_who_measured_of.html. Retrieved 16 November 2010.
- ^ "Muere Allan Sandage, uno de los astrónomos más importantes del siglo XX". El Pais. 16 November 2010. http://www.elpais.com/articulo/sociedad/Muere/Allan/Sandage/astronomos/importantes/siglo/XX/elpepusoc/20101116elpepusoc_12/Tes. Retrieved 16 November 2010.
- ^ a b c Overbye, Dennis (17 November 2010). "Allan Sandage, Astronomer, Dies at 84; Charted Cosmos’s Age and Expansion". New York Times. http://www.nytimes.com/2010/11/17/science/space/17sandage.html?_r=1&ref=obituaries. Retrieved 17 November 2010.
- ^ "Carnegie Observatories-Pasadena". http://obs.carnegiescience.edu/personnel/contact/. Retrieved 2009-12-04.
- ^ The educational website SuperScholar includes Sandage on its list of "The 20 Most Influential Scientists Alive Today."
- ^ In the 1952 Conference of the International Astronomical Union, held in Rome
- ^ Simon Sing (2004) Big Bang
- ^ Sandage, A. R. (May 1958). "Current Problems in the Extragalactic Distance Scale". Astrophysical Journal 127 (3): 513–526. Bibcode 1958ApJ...127..513S. doi:10.1086/146483.
- ^ Eggen, O. J., Lynden-Bell, D., Sandage, A. R. (November 1962). "Evidence from the motions of old stars that the Galaxy collapsed". Astrophysical Journal 136: 748–766. Bibcode 1962ApJ...136..748E. doi:10.1086/147433.
- ^ Sandage, A. (April 1990). "On the formation and age of the Galaxy". Royal Astronomical Society of Canada 84: 70–88. Bibcode 1990JRASC..84...70S. ISSN 0035-872X.
- ^ Sandage, A.R. (March 1961). "The Ability of the 200-inch Telescope to Discriminate Between Selected World Models". Astrophysical Journal 133 (2): 355–392. Bibcode 1961ApJ...133..355S. doi:10.1086/147041.
- ^ Sandage, A. R. (1961). The Hubble atlas of galaxies. Washington: Carnegie Institution. Bibcode 1961hag..book.....S. ISBN 0-87279-629-9.
- ^ Sandage, A.R., Tammann, G. A. (1981). A revised Shapley-Ames Catalog of bright galaxies. Washington: Carnegie Institution. Bibcode 1981rsac.book.....S. ISBN 0-87279-652-3.
- ^ A. Sandage, Astrophys. J. 139, 319 (1962)
- ^ Corasaniti, P. S., Melchiorri, A. & Huterer, D. (2007). "Exploring the Dark Energy Redshift Desert with the Sandage-Loeb Test". Physical Review D 75 (6): 062001. arXiv:astro-ph/0701433. Bibcode 2007PhRvD..75f2001C. doi:10.1103/PhysRevD.75.062001.
- ^ Lynds, C. R.; Sandage, A. R. (May 1963). "Evidence for an Explosion in the Center of the Galaxy M82". Astrophysical Journal 137 (4): 1005–1021. Bibcode 1963ApJ...137.1005L. doi:10.1086/147579.
- ^ As shown by a Smithsonian Astrophysical Observatory/NASA Astrophysics Data System search that was performed in 2009
- ^ "Allan Sandage". The Telegraph. 21 November 2010. http://www.telegraph.co.uk/news/obituaries/science-obituaries/8150004/Allan-Sandage.html. Retrieved 26 August 2011.
- Carnegie Cosmologist Allan Sandage Dies, "Sandage joined the staff of the Carnegie Observatories in 1952 and, after Hubble’s death in 1953; Sandage became responsible for the cosmology program using telescopes at Mount Wilson and Palomar"
Further reading
- Alan P. Lightman and Roberta Brawer, Origins: the lives and worlds of modern cosmologists, Harvard University Press, 1990. Interviews with modern cosmologists, including Sandage.
- Lynden-Bell, Donald; Schweizer, Francois (2012), "Allan R. Sandage, 18 June 1926 - 13 November 2010", Biographical Memoirs of the Fellows of the Royal Society, arXiv:1111.5646, Bibcode 2011arXiv1111.5646L
- Timothy Ferris, The Red Limit: The Search for the Edge of the Universe, Harper Perennial, 2002. Non-technical description of research, primarily up to about 1980, on cosmology; Sandage was a key figure, and features accordingly.
- Dennis Overbye, Lonely Hearts of the Cosmos: the story of the scientific quest for the secret of the Universe, HarperCollins 1991, Back Bay (with new afterword), 1999. Historical account of modern cosmology told through the careers of the scientists involved, in which Sandage is the central character. Complementary to Origins.
- Allan Sandage, The Mount Wilson Observatory. Centennial History of the Carnegie Institution of Washington, Vol. 1. Cambridge University Press, 2004. Sandage's account of the observatory where he worked, with the background to his own work with Hubble and others.
External links
- Bruce Medalist page on Allan Sandage
- Allan Sandage directory page at the IAU
- Allan Sandage page at The Carnegie Observatories
- Rowan-Robinson, Michael (2011). "Obituaries: Allan Rex Sandage". Physics Today 64 (6). http://ptonline.aip.org/journals/doc/PHTOAD-ft/vol_64/iss_6/64_1.shtml?type=PTALERT.
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Oxford Dictionary of Scientists
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Mentioned in
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