Nature 298, 350 - 354 (22 July 1982); doi:10.1038/298350a0

Evidence for an oblique magnetic solar rotator

D. O. Gough

Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK

The observation by Claverie et al. ¹. of fine structure in the peaks in the power spectrum of low-degree 5-min solar oscillations has been interpreted as being a result of rotational splitting. Claverie et al. ¹ claim that their measurements imply that an appropriately weighted average of the interior angular velocity (r) of the Sun is about twice the value of at the surface. At first sight their claim looks doubtful, because all 2l + 1 components of the set of modes of degree l appear in the spectrum, whereas only l + 1 of them should be detectable. However, Isaak² has recently speculated that the additional components are produced by an intense rotating magnetic core, such as had been postulated by Dicke^3,4 to account for the 12.2-day periodic component in the Princeton oblateness data⁵⁻⁹. Isaak² pointed out that the mean period 2/15 days of the solar interior that was inferred from the Birmingham data¹ is consistent with a central core rotating with the 12.2-day period and an outer envelope rotating with the photosphere. Moreover, his rough estimate of a few megagauss for the r.m.s. magnetic field that is required to support his conjecture is within about a factor 10 of that required by Dicke³. Thence he concluded that the Birmingham data¹ provide the first clear empirical evidence for an intense internal solar magnetic field. Here I examine this evidence in more detail, and show that the conclusion is premature. If the magnetic core does exist, the 5-min oscillations provide no clear evidence that it is rotating rapidly. Furthermore, unless one accepts a contrived magnetic-field configuration, an explanation for the 2l + 1 components of the multiplets is still lacking.

References

1.	Claverie, A., Isaak, G. R., McLeod, C. P. & van der Raay, H. B. Nature 293, 443−445 (1981). | ISI |
2.	Isaak, G. R. Nature 296, 130−131 (1982). | ISI |
3.	Dicke, R. H. Proc. Informal Conf. on Status and Future of Solar Neutrino Research Vol. 2 (ed. Friedlander, G.) 109−143 (Brookhaven National Laboratory, Upton, 1978).
4.	Dicke, R. H. New Scient. 83, 12−14 (1979). | ISI |
5.	Dicke, R. H. & Goldenberg, H. M. Astrophys. J. Suppl. 27, 131−182 (1974). | Article | ISI |
6.	Dicke, R. H. Phys. Rev. Lett. 37, 1240−1242 (1976). | Article | ISI |
7.	Dicke, R. H. Solar Phys. 47, 475−515 (1976). | ISI |
8.	Dicke, R. H. Proc. natn. Acad. Sci. U.S.A. 78, 1309−1312 (1981).
9.	Dicke, R. H. Proc. natn. Acad. Sci. U.S.A. 78, 1989−1993 (1981).
10.	Grec, G., Fossat, E. & Pomerantz, M. Nature 288, 541−544 (1980). | ISI |
11.	Fossat, E., Grec, G. & Pomerantz, M. Solar Phys. 74, 59−63 (1981). | ISI |
12.	Deubner, F.-L. Nature 290, 682−683 (1981). | ISI |
13.	Christensen-Dalsgaard, J. & Gough, D. O. Nature 288, 544−547 (1980). | ChemPort |
14.	Christensen-Dalsgaard, J. Proc. 5th Eur. Meet. in Astronomy (ed. Ledoux, P.) A.1.1−A.1.28 (Institut d'Astrophysique, Liège, 1980). | ChemPort |
15.	Scuflaire, R., Gabriel, M. & Noels, A. Astr. Astrophys. 99, 39−42 (1981). | ISI |
16.	Christensen-Dalsgaard, J. & Gough, D. O. Astr. Astrophys. 104, 173−176 (1981). | ChemPort |
17.	Christensen-Dalsgaard, J. & Gough, D. O. Mon. Not. R. astr. Soc. 198, 141−171 (1982). | ChemPort |
18.	Vandakurov, Yu, V. Astr. Zh. 44, 786−797 (1967).
19.	Gough, D. O. Mon. Not. R. Astr. Soc. 196, 731−745 (1981). | ISI |
20.	Brookes, J. R., Isaak, G. R. & van der Raay, H. B. Mon. Not. R. astr. Soc. 185, 1−17 (1978). | ISI | ChemPort |
21.	Scherrer, P. H., Wilcox, J. M., Christensen-Dalsgaard, J. & Gough, D. O. Solar Phys. (in the press).
22.	Ledoux, P. & Simon, R. Ann. Astr. 20, 185−195 (1957).
23.	Goossens, M. Astrophys. Space Sci. 16, 386−404 (1972). | ISI |
24.	Goossens, M., Smeyers, P. & Denis, J. Astrophys. Space Sci. 39, 257−272 (1976). | ISI |
25.	Biront, D., Goossens, M., Cousens, A. & Mestel, M. Mon. Not. R. astr. Soc. (in the press).
26.	Mestel, L., Q. Jl R. astr. Soc. 12, 402−416 (1971).
27.	Mestel, L. & Takhar, H. S. Mon. Not. R. astr. Soc. 156, 419−436 (1972). | ISI |
28.	Mestel, L., Nittman, J., Wood, W. P. & Wright, G. A. E. Mon. Not. R. astr. Soc. 195, 979−1000 (1981). | ISI |
29.	Dicke, R. H. Solar Phys. 78, 3−16 (1982). | ISI |
30.	Hill, H. A. et al. Phys. Rev. Lett. 33, 1497−1500 (1974). | Article | ISI |
31.	Bos, R., Goode, P. R. & Hill, H. A. Phys. Rev. Lett. (submitted).
32.	Gough, D. O. Nature 298, 334−339 (1982). | Article | ISI |