دونالد لندون-بل

Donald Lynden-Bell
Donald Lynden-Bell.jpg
Lynden-Bell in 2008
وُلِدَ(1935-04-05)5 أبريل 1935
Dover, United Kingdom[1]
توفي6 فبراير 2018(2018-02-06) (aged 82)[2]
Cambridge, United Kingdom
المدرسة الأمUniversity of Cambridge
الجوائزKarl Schwarzschild Medal (1983)

Eddington Medal (1984)
Brouwer Award (1991)
Gold Medal of the Royal Astronomical Society (1993)
Bruce Medal (1998)
John J. Carty Award for the Advancement of Science (2000)
Henry Norris Russell Lectureship (2000)

Kavli Prize for Astrophysics (2008)
السيرة العلمية
المجالاتAstrophysics
الهيئاتUniversity of Cambridge
أطروحةStellar and galactic dynamics (1961)
المشرف على الدكتوراهLeon Mestel
طلاب الدكتوراهOfer Lahav
Somak Raychaudhury
Simon White

Donald Lynden-Bell CBE FRS[3] (5 April 1935 – 6 February 2018) was a British theoretical astrophysicist. He was the first to determine that galaxies contain supermassive black holes at their centres, and that such black holes power quasars.[4] Lynden-Bell was President of the Royal Astronomical Society (1985–1987) and received numerous awards for his work, including the inaugural Kavli Prize for Astrophysics. He worked at the University of Cambridge for his entire career, where he was the first director of its Institute of Astronomy.

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Biography

Lynden-Bell was born at Dover Castle in Dover, Kent, into a military family,[5] as one of two children to Lachlan Arthur Lynden-Bell (1897–1984) and Monica Rose Thring (1906–1994). His father, a lieutenant colonel, fought on the Western Front and in the Middle East during World War I and had received a Military Cross.[6] He had a sister, Jean Monica, who became a prominent music teacher in Canada.[5][7]

He attended Marlborough College before being admitted to Clare College, Cambridge in 1953.[8] After earning a distinction in the Mathematical Tripos,[8] Lynden-Bell went on to doctoral studies in theoretical astronomy working with Leon Mestel, which he completed in 1960.[9] In 1962, he published research with Olin Eggen and Allan Sandage[10] arguing that the Milky Way originated through the dynamic collapse of a single large gas cloud.[11] In 1969 he published his theory that quasars are powered by massive black holes accreting material. From counting dead quasars, he deduced that most massive galaxies have black holes at their centres.[12]

Lynden-Bell developed a theory for the relaxation of a system of particles in changing potential field known as "violent relaxation." Violent relaxation has many applications in dynamical astronomy, affecting the orbits of stars within star clusters and galaxies.[13] Lynden-Bell is also known for the development of the theory of the "gravothermal catastrophe," a phenomenon in star clusters that is the result of the negative heat capacity of gravitational systems. The catastrophe occurs when the core of a cluster shrinks and heats up, causing it to transfer energy to stars in the cluster's halo, leading the cluster core to collapse.[14]

Lynden-Bell authored an influential 1974 paper with James E. Pringle about the evolution of disks around "nebular variables," which were later to become known as T Tauri stars – an early phase in a star's life cycle.[15] The paper predicts the signature of radiation from such disks, which is emitted primarily at infrared wavelengths where it dominates over the emission from the star.[16] Excess infrared emission from young stars has become one of the primary methods used to identify these objects in astronomical surveys.[17]

In 1971, he became Professor of Astrophysics (1909) and later the first director of the Institute of Astronomy, Cambridge, when it formed from the merger of the Institute of Theoretical Astrophysics and the Cambridge Observatories in 1972.[8]

In the 1980s, he was a member of a group of astronomers known as the 'Seven Samurai' (with Sandra Faber, David Burstein, Alan Dressler, Roger Davies, Roberto Terlevich, and Gary A. Wegner) who postulated the existence of the Great Attractor, a huge, diffuse region of material around 250 million light-years away that results in the observed motion of our local galaxies.[18]

Lynden-Bell, Roger Griffin, Neville Woolf, and Wallace L. W. Sargent were in the 2015 documentary film Star Men that covered some of their professional accomplishments at their fiftieth reunion to redo a memorable hike.[19]

His research in the last years of his life mainly focused on astrophysical jets and general relativity.[20]


Personal life and death

Donald was married to Ruth Lynden-Bell, a professor of chemistry at the University of Cambridge, on 1 July 1961.[21]

Lynden-Bell died at his home in Cambridge on 6 February 2018, at the age of 82.[2] He had a stroke in the months preceding his death, and never fully recovered.[22] Responding to news of his death, John Zarnecki, then President of the Royal Astronomical Society, praised Lynden-Bell's contributions to astronomy, particularly his "incisive questions at scientific meetings and being generous in his support for others".[23]

Honours

Awards

Named after him

References

  1. ^ "The Astronomers". Star Men. Inigo Athenaeum Enterprise Inc. 2015. Retrieved 25 October 2016.
  2. ^ أ ب "Prof. Donald Lynden-Bell". Institute of Astronomy, University of Cambridge. 6 February 2018. Retrieved 6 February 2018.
  3. ^ Evans, Neil Wyn (2020). "Donald Lynden-Bell. 5 April 1935— 6 February 2018". Biographical Memoirs of Fellows of the Royal Society. 69: 333–363. doi:10.1098/rsbm.2020.0008.
  4. ^ أ ب Davies, Roger (28 February 2018). "Donald Lynden-Bell (1935–2018)". Obituary. Nature. 555 (7695): 166. Bibcode:2018Natur.555..166D. doi:10.1038/d41586-018-02579-w. PMID 29517024.
  5. ^ أ ب "Donald Lynden-Bell". The Times. 9 February 2018. p. 53.
  6. ^ أ ب "2008 Kavli Prize Laureates in Astrophysics". www.kavliprize.org. 28 August 2008.
  7. ^ Rowan-Robinson, Michael (27 February 2018). "Donald Lynden-Bell obituary". The Guardian (in الإنجليزية). Retrieved 27 February 2018.
  8. ^ أ ب ت Lynden-Bell, Donald (2010), "Searching for Insight", Annual Review of Astronomy and Astrophysics 48: 1–19, doi:10.1146/annurev-astro-081309-130859, Bibcode: 2010ARA&A..48....1L 
  9. ^ Lynden-Bell, Donald (1960). Stellar and Galactic Dynamics (PhD). University of Cambridge.
  10. ^ Lynden-Bell, Donald; Schweizer, François (2012). "Allan Rex Sandage. 18 June 1926 – 13 November 2010". Biographical Memoirs of Fellows of the Royal Society. 58: 245–264. arXiv:1111.5646. Bibcode:2012BMFRL..58..245L. doi:10.1098/rsbm.2011.0021. S2CID 72680092.
  11. ^ Eggen, O. J.; Lynden-Bell, D.; Sandage, A. R. (1962). "Evidence from the motions of old stars that the Galaxy collapsed". The Astrophysical Journal. 136: 748. Bibcode:1962ApJ...136..748E. doi:10.1086/147433.
  12. ^ Lynden-Bell, D. (1969). "Galactic Nuclei as Collapsed Old Quasars". Nature. 223 (5207): 690–694. Bibcode:1969Natur.223..690L. doi:10.1038/223690a0. S2CID 4164497.
  13. ^ Lynden-Bell, D. (1967). "Statistical mechanics of violent relaxation in stellar systems". Monthly Notices of the Royal Astronomical Society. 136: 101–121. arXiv:astro-ph/0212205. Bibcode:1967MNRAS.136..101L. doi:10.1093/mnras/136.1.101.
  14. ^ Lynden-Bell, D.; Wood, Roger (1968). "The gravo-thermal catastrophe in isothermal spheres and the onset of red-giant structure for stellar systems". Monthly Notices of the Royal Astronomical Society. 138 (4): 495. Bibcode:1968MNRAS.138..495L. doi:10.1093/mnras/138.4.495.
  15. ^ Aswin Sekhar (15 February 2018). "Donald Lynden-Bell: A Legacy of Astronomical Excellence". thewire.com.
  16. ^ Lynden-Bell, D.; Pringle, J. E.; et al. (1974). "The evolution of viscous discs and the origin of the nebular variables". Monthly Notices of the Royal Astronomical Society. 168 (3): 603. Bibcode:1974MNRAS.168..603L. doi:10.1093/mnras/168.3.603.
  17. ^ Lada, Charles J.; Lada, Elizabeth A.; et al. (2003). "Embedded Clusters in Molecular Clouds". Annual Review of Astronomy and Astrophysics. 41: 57–115. arXiv:astro-ph/0301540. Bibcode:2003ARA&A..41...57L. doi:10.1146/annurev.astro.41.011802.094844. S2CID 16752089.
  18. ^ Dennis Overbye, Lonely Hearts of the Cosmos, 1st. ed., p. 410, Harper Collins, 1991
  19. ^ Bradshaw, Peter (19 November 2015). "Star Men review – desert road trip, space odyssey". the Guardian (in الإنجليزية). Retrieved 7 February 2018.
  20. ^ "Donald Lynden-Bell, British astronomer – Stock Image C020/7225 – Science Photo Library". www.sciencephoto.com. Retrieved 7 February 2018.
  21. ^ "Professor emeritus Ruth Lynden-Bell". AcademiaNet.
  22. ^ "R.I.P. Donald Lynden-Bell (1935–2018)". WordPress. 6 February 2018.
  23. ^ Hollis, Morgan (19 February 2018). "Professor Donald Lynden-Bell CBE FRS, 1935–2018" (in الإنجليزية البريطانية). Royal Astronomical Society. Retrieved 27 February 2018.
  24. ^ "Recipients of the Karl Schwarzschild Medal – English" (in الإنجليزية). Astronomische Gesellschaft. Retrieved 7 February 2018.
  25. ^ Hide, R. (1984), "Presentation of the Eddington Medal to Lynden-Bell 1984FEB10", Quarterly Journal of the Royal Astronomical Society 25: 231, Bibcode: 1984QJRAS..25..231H 
  26. ^ "Donald Lynden-Bell received the 1991 Dirk Brouwer Award of the American Astronomical Society.", Physics Today 44 (1): Q82, 1991, doi:10.1063/1.2809968, Bibcode: 1991PhT....44Q..82. 
  27. ^ "Gold Medal to Lynden-Bell", Quarterly Journal of the Royal Astronomical Society 34: 273, 1993, Bibcode: 1993QJRAS..34..273. 
  28. ^ "Past Recipients of the Catherine Wolfe Bruce Gold Medal « Astronomical Society". Astronomical Society of the Pacific. Archived from the original on 4 September 2017. Retrieved 7 February 2018.
  29. ^ "John J. Carty Award for the Advancement of Science". National Academy of Sciences. Archived from the original on 29 December 2010. Retrieved 15 February 2011.
  30. ^ "Henry Norris Russell Lectureship | American Astronomical Society" (in الإنجليزية). American Astronomical Society. Retrieved 7 February 2018.
  31. ^ "Gruppe 2: Fysikkfag (herunder astronomi, fysikk og geofysikk)" (in النرويجية). Norwegian Academy of Science and Letters. Retrieved 7 October 2010.
  32. ^ "IAU Minor Planet Center: (18235) Lynden-Bell". Retrieved 7 February 2018.
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