Premium
Evidence for a primordial magnetic field during the meteorite parent body era
Author(s) -
Sonett C. P.
Publication year - 1978
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl005i002p00151
Subject(s) - meteorite , remanence , achondrite , magnetization , demagnetizing field , field (mathematics) , magnetic moment , physics , astrophysics , field strength , magnetism , magnetic field , geology , condensed matter physics , geophysics , chondrite , astrobiology , mathematics , pure mathematics , quantum mechanics
A total of 247 measurements of natural magnetic remanence (NRM) and effective susceptibility of meteorites tabulated by Herndon et al . (1972) from Russian data is investigated. A log‐log plot ofp ¯ , magnetic moment/gm, versusx ¯ , susceptibility/gm, shows a straight line relation with a slope of unity over a range of meteorite types extending from the achondrites at the low Fe‐Ni end to the stony‐irons, and over a span inp ¯andx ¯of between four and five orders. In view of the wide variability of the different classes of meteorite and the effects of unstable soft magnetization, this relation is unexpected. One suggestion is a common background field; this supports the hypothesis of an ancient magnetic field at the time of meteorite formation. An estimate of the primordial field strength cannot be made with certainty because the field strength H = 1.8/ρ ²N, where ρ is density and N is the average carrier demagnetization factor; N can vary from zero to 4 π. Thus an extreme lower limit for H is 0.02 oersted for N = 4 π, in agreement with Brecher and Ranganayaki (1975). For the mean field of 0.27 oersted determined from critical study of individual meteorites ( Stacey and Banerjee , 1974), the average N = 0.74, corresponding to elongated grains.