Charles Thomas Bolton (born 1943) is an American astronomer who was one of the first astronomers to present strong evidence of the existence of a stellar-mass black hole.[1][2]

Charles Thomas Bolton
Known forEvidence for Stellar-mass black holes
AwardsFellow of the Royal Society of Canada
Scientific career
InstitutionsDavid Dunlap Observatory, University of Toronto


Early life and educationEdit

Tom Bolton was born in Camp Forrest, a military base in Tullahoma, Tennessee.[1] He received his Bachelor's in 1966 from the University of Illinois, followed by a 1968 Master's and a 1970 doctoral degrees from the University of Michigan.[1]


Bolton then worked as a postdoctoral researcher at the David Dunlap Observatory, teaching there until 1972.[1] He taught at Scarborough College from 1971 to 1972, and at Erindale College from 1972 to 1973, but since 1973, has been affiliated with the University of Toronto astronomy department,[1] where he is now an emeritus professor.[3]

In 1970, Bolton developed the first computer models for stellar spectra that were precise enough to compare with data from real stars.[1]

In 1971, as a post-doctoral fellow and part-time faculty member studying binary systems at the Dunlap Observatory,[4][5] Bolton observed star HDE 226868 wobble as if it were orbiting around an invisible but massive companion emitting powerful X-rays,[1][6] independently of the work by Louise Webster and Paul Murdin, at the Royal Greenwich Observatory.[7] Further analysis gave an estimate about the amount of mass needed for the gravitational pull, which proved to be too much for a neutron star. After more observations confirmed the results, by 1973, the astronomical community generally recognized black hole Cygnus X-1, lying in the plane of the Milky Way galaxy at a galactic latitude of about 3 degrees.[1][8][9][10]

In 1985, Bolton and Douglas Gies showed that hot, massive "runaway OB stars" (stars that travel at an abnormally high velocity relative to the surrounding interstellar medium), could be accelerated through stellar interactions within star clusters, in addition to being ejected from binary systems after supernova explosions.[11][1]

Bolton was instrumental in passing the first light pollution regulation Canada, a 1995 bylaw to limit light pollution in the town Richmond Hill, Ontario, home of the David Dunlap Observatory.[1][12]

Awards and recognitionEdit

Bolton is a fellow of the Royal Society of Canada.[1]


  1. ^ a b c d e f g h i j k "Charles Thomas Bolton (1943- )". Virtual Museum of Canada. Retrieved 2007-07-05.
  2. ^ Black, Harry (2008). "Tom Bolton, Astronomer: Discoverer of the First Black Hole". Canadian Scientists and Inventors: Biographies of People Who Shaped Our World. Pembroke Publishers Limited. pp. 24–27. ISBN 978-1-55138-222-7..
  3. ^ Faculty profile Archived 2012-07-18 at, U. of Toronto Astronomy and Astrophysics Dept.
  4. ^ Culp, Kritine. "The proof is out there". University of Toronto Magazine. Retrieved 2008-07-06.
  5. ^ "Black holes: The Canadian connection". Quirks and Quarks. CBC. 2008-04-18. Retrieved 2008-07-05.
  6. ^ Bolton, C. T. (1972). "Identification of Cygnus X-1 with HDE 226868". Nature. 235 (5336): 271–273. Bibcode:1972Natur.235..271B. doi:10.1038/235271b0. Retrieved 2008-03-10.
  7. ^ Webster, B. Louise; Murdin, Paul (1972). "Cygnus X-1—a Spectroscopic Binary with a Heavy Companion?". Nature. 235 (5332): 37–38. Bibcode:1972Natur.235...37W. doi:10.1038/235037a0. Retrieved 2008-03-10.
  8. ^ Rolston, Bruce (November 10, 1997). "The First Black Hole". University of Toronto. Archived from the original on 2008-03-07. Retrieved 2008-03-11.
  9. ^ Shipman, H. L. (1975). "The implausible history of triple star models for Cygnus X-1 Evidence for a black hole". Astrophysical Letters. 16 (1): 9–12. Bibcode:1975ApL....16....9S. doi:10.1016/S0304-8853(99)00384-4.
  10. ^ Gursky, H.; Gorenstein, P.; Kerr, F. J.; Grayzeck, E. J. (1971). "The Estimated Distance to Cygnus X-1 Based on its Low-Energy X-Ray Spectrum". Astrophysical Journal. 167: L15. Bibcode:1971ApJ...167L..15G. doi:10.1086/180751.
  11. ^ Gies, D. R.; Bolton, C. T. (1986). "The binary frequency and origin of the OB runaway stars". The Astrophysical Journal Supplement Series. 61: 419. doi:10.1086/191118. ISSN 0067-0049.
  12. ^ "Lights out for pollution | The Star". Retrieved 2018-10-30.