polytropen.adj.
/ˈpɒlɪtrəʊp/, U.S. /ˈpɑliˌtroʊp/ A. n.† 1. A scientific instrument (not identified). Obsolete. rare.The instrument referred to may be that devised by G. E. Sire of France, which was a form of gyroscope for demonstrating the effect at different latitudes of the rotation of the earth on a rotating body. No mention of Magnus's polytrope occurs in the reports of the British Association for the Advancement of Science for 1854, a meeting of which quot. 1854 is reporting.
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1854 Times 25 Sept. 8/4 M. Gassiot exhibited during the evening some experiments with Ruhmkorff's induction coils and with Professor Magnus's polytrope—sounds of no import to the many, but of evident interest to the scientific throng in the hall.
2. Physics and Astronomy. A polytropic body of gas. Cf. polytropic adj. 5.
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the world > matter > physics > mechanics > dynamics > thermodynamics > [noun] > polytropic body of gas
polytrope1926
1926 A. S. Eddington Internal Constit. Stars iv. 86 The polytrope n = 3, which is believed to correspond nearly to the actual conditions of the stars.
1939 S. Chandrasekhar Introd. Study Stellar Struct. iv. 170 So far we have considered only complete polytropes. We shall now proceed to a consideration of composite polytropes, i.e., configurations which consist of different zones each characterized by a different value of the index n.
1975 Nature 27 Mar. 295/1 The energy required to break up a star of mass m and radius R is..¾(Gm2/R) for a polytrope of index n = 3½.
2005 Physical Rev. D. 71 24035-1 The initial stellar models are modeled as relativistic polytropes which are either secularly or dynamically unstable.
B. adj.
Physics and Astronomy. = polytropic adj. 5.
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the world > matter > physics > electromagnetic radiation > heat > [adjective] > of constant specific heat
polytropic1907
polytrope1939
1939 Physical Rev. 55 379/1 Polytrope solutions exist for both.
1968 Planetary & Space Sci. 16 1483 3/2 for the polytrope index represents a critical value.
2004 Astrophysical Jrnl. 605 793 Using the polytrope model of hot gas..we corrected for the density gradient and estimated the midplane O vii density at the solar neighborhood.
This entry has been updated (OED Third Edition, September 2006; most recently modified version published online March 2022).
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n.adj.1854