Robert Julius Trumpler

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Robert Julius Trumpler

Robert Julius Trumpler (until 1915 Robert Trümpler, October 2, 1886, in Zürich, Switzerland – September 10, 1956, in Berkeley, United States) was a Swiss-American astronomer.

Career

After initial schooling, Trumpler entered the

United States National Academy of Sciences in 1932.[1]

He is most noted for observing that the brightness of the more distant

interstellar extinction of light.[2]

Trumpler further studied and catalogued open clusters in order to determine the size of the

Trumpler classification,[3]
is still in use today.

Honors

The Robert J. Trumpler Award, awarded by the Astronomical Society of the Pacific for an outstanding PhD Thesis in astronomy, is named in his honor.[4]

The following celestial features are named after him:

Trumpler Classification for open star clusters

Trumpler's classification method for open star clusters is still currently in use by astronomers. It classifies the star cluster according to three features: Degree of concentration, range of magnitude (brightness) for the stars found in the cluster and the number of stars in the cluster. Degree of concentration is given a number from 1 to 4 in Roman numerals (number I indicating a strong central concentration, II indicating little central concentration, III indicates no noticeable concentration and IV little difference from the surrounding stellar population).[5][6]

Range of magnitude is classified in a scale 1 to 3 and is written in Arabic numerals. Number 1 indicates most stars within the cluster have a very similar apparent brightness. 2 indicates a medium range across the stars in the cluster and 3 indicates a significant difference in brightness, from very bright to very faint stars.[5][6]

The third feature classifies the number of stars inside the cluster and it uses letters. Letter 'p' indicates a poor cluster, containing less than 50 stars. Letter 'm' indicates a medium amount of 50 to 100 stars. Letter 'r' indicates a rich cluster, containing more than a 100 stars. Finally, the letter 'n' is attributed to all star clusters where some sort of nebulosity is present. For example, NGC 5460 is classified as a II3m, an open cluster with little central concentration, significant difference in brightness among its stars and 50 to 100 stars within the cluster. Since no nebulosity is detected, the letter n is not attributed to it.[6]

Notable objects

Trumpler 14, an open cluster in the constellation Carina

Some notable objects from his 1930 catalogue of open clusters are:

Selected publications

  • R.J. Trumpler, 1930. "Preliminary results on the distances, dimensions and space distribution of open star clusters." Lick Obs. Bull. Vol XIV, No. 420 (1930) 154-188. Table 16 is the Trumpler catalog of open clusters, referred to as "Trumpler (or Tr) 1-37
  • Robert Julius Trumpler, Harold F. Weaver 1962. Statistical Astronomy (Dover Publications, New York). (reprinted from original published by the University of California, Berkeley, 1953)

See also

References

  1. ISBN 978-0-309-07035-5
    .
  2. ^ R.J. Trumpler, 1930. Preliminary results on the distances, dimensions and space distribution of open star clusters. Lick Obs. Bull. Vol XIV, No. 420 (1930) 154-188. Table 16 is the Trumpler catalog of open clusters, referred to as "Trumpler (or Tr) 1-37
  3. ISBN 978-0-521-59889-7
    ; p.74
  4. ^ Robert J. Trumpler Award for an Outstanding PhD Thesis.[permanent dead link] Astronomical Society of the Pacific. Accessed September 7, 2008.
  5. ^ a b "Trumpler classification". Oxford Reference. Retrieved 2023-12-07.
  6. ^ a b c "Archives". Olympic Astronomical Society. 2013-12-04. Retrieved 2023-12-07.

Further reading

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