ellipticity -3-

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Third Cycle 1n Astronomy TIlE SOLAR WIND (21 October 1975) - J. LEMAIRE

1.- Some historical steps 1n coronal and solar wind SC1ences

After 1840 the corona was considered as extension of atmosphere of sun.

- 1869

- 1875

- 1896

Spectroscopic observation of f.reen coronal line A 5303 )\ (YOUNG)

Streamers associated with sunspots (SECCHI)

correlation between SUNSPOTS NUt~ER and ellipticity of coronal isophotes .- distinction bet\veen K (polarized) and F (unpolarized) coronae. - Reflexion of photospheric light by free electrons

(T ~ 5000 K) produce K cont inum spectrum

- hy 1930 : 18 coronal emlSSlon lines observed - they are attributed to

- 1930

- 1942

- 1945

- 1964

CORONIU11 (!?)

LYOT develops the coronograph - t!A5303i\ = {'-.9 )1.., is indication for high temperature, but atomic mass, of coronium unknoun ! v

=

V2leT 1m .

corona coronlum

EDLEN, identifies red line (A = 7892 )1..) as forbidden transition of FeXI - New indication of hi~h temperature: T. . . = 0,5 -

lOlllZatlon 1.1 x 106

K

T

=

1.5 - 1.8 x 10 h K, \v/1en deduced from observed electron corona

density gradient

new recombination process found by BURGESS - As a consequence,

.~ 6

T - T - 1.5 - £.0 x 10 K

(ionization) - (L'lA Doppler)-

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- 1903

- 1931

- 1943

- 1931

BIRKELAHD and STOR~lE~ consider that sporad ic charged particle emission propagates from SUN to EARTH and generate AURORAE

magnetic storm effect also explained by sporadic solar corpuscular radiation (CHAPNAN and FERRARO).

aherration angle of comet tails indicate existence a mOVIng interplanetary medium (f!OFPIEISTER)

acceleration of irregularities In comet tails also indicate continous outward streaming of solar corpuscular radiation

(H IE R'1:\NN)

- 1938 - 1960 : Anti correlation of solar activity and cosmIC ray Forbush decrease also indicates presence beyond the corona of, streaming solar

(magnetized) material. (GOLD, 1960)

- 1957

- 1958

- 1960

- 1969

CHAPl'IMI shows importance of heat conduction by free electrons in corona, he extends hydrostatic model of corona beyond 1 A.U.

PARKER shm·;s that hydrostatic models are convectivcly unstahle (poo too large) - he proposes hydrodynamic supersonic expansion (solar wind)

CHM18ERLAIN, suggest an evaporative (subsonic) type expansion (solar breeze)

A controversy develloped.

Recent spacecraft observations confirmed PARKER supersonic velocities at 1 AU. Evaporative model fel into discredit.

It is found that with a correct exospheric electric field evaporative models also. lead to supersonic velocities at lAU. JOCKERS and

LL~~IRE - SCHFRER.

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- 1959

.., 1961

- 1962

Lunik III, Venus I, detect charged particle fluxes of ~

9 -2 -1 P

10 cm sec (GRINGJ\UZ)

Explorer 10 1 2 108 -2 -1 -

280 km/sec

; ¢

= -

^x ^cm ^sec ^v

=

^;

3 8 -3 P lOS _or.LT. _;::roup) questionable ! ?

n

r = -

^cm T ^p '" ^K

Hariner 2 .: solar wind detected at all times ; v '" 300 - 860 km/sec

-3 -5

v =

500 km/sec ; n

=

5 cm : B

=

5 10 Gauss ...

r

After 1962 an over whelming amount of data came in.

These observations Hill be presented in the next lesson 1n a non-historic order.

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lHBLI0GRAPHICAL p.EFEnENCES

BIERMANN,L., (1951), Comet tails and solar corpuscular radiation, Z. Ap., 29,

~

274.

BOWEN, I.S., and EDLEN, B., (1939), FeVII 1.n Nova Pictoris, Nature, 143, )74.

BURGESS, A., (964), Dielectronic recombination and the temperature of the solar Corona, Ap. J., 139, 776.

CHMtBERLAIN, J.I;I., (960), Ap. J., 131, 45.

CHJ\Pr-W~, S., and FERRARO, V.C.A., (931), Terrest. Nagnetism and Atmospheric Elec., 36, 77, 171.

CHAPMAN, S., (957), Notes on the solar corona and the terrestrial ionosphere, Smithson. Contr. Astrophys., 2, 1-12.

DESSLER, A.J., (1967), Revs. Geopbys., 5, l . FORBUSH, S.E., 0938a), Phys. Rev., 5/~, 975.

FORBUSH, S.E., STINCHCOHtI, T.B., and SCBEH1, H., (950), Phys. Rev., 79, 501.

GOLD, T., (1960), Astrophys. J. Suppl., 4, 406.

GROTRIAN, \'1., (931), 7.. Ap., 3, 199.

HOFFMEISTER, C., (1943), ~s. f. Astrophys., 23,265.

HUNDHAUSEN, A.J. (1972), Coronal expansion and solar wind, Springer-Verlag, B Berlin.

JOCKERS, K., (970), Solar Hind models based on exosplleric theory, Astron.

Astrophys., 6, 219-239.

LYOT, B., (1932), Study of the solar corona in the ahsence of an eclipse,

z.

^Ap., ^{5, 73.}

LEMAIRE, J., and r'L SCHERER, Le champ electrique de polarisation dans l'exosphere ioni~ue polaire, C;H. Acad. Sc. Paris, 269, 666-669,

LEHAIRE, J. and H. SCHERER, (1971), Kinetic Hode Is of the Solar ~'!ind, JGR, 76, 7479.

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LEt1AIRE, J., and t1. SCHERER, (1973), Kinetic Models of the Solar and polar h·inds, Rev. Geophys. and space physics, 11, 427-468.

MACKIN, R.J. and M. NEUGEBAUER, Eds., (1966), The Solar Ivinci, Pergamon Press, New York.

PARKER, E.N., (1963), Interplanetary Dynamical Processes, Interscience Publishers, New York.

PARKER, E.N., (1969), Theoretical Studies of the solar "lind phenomenon, Space Sci. Rev., 9, 325-360.

PARKER, E.N., (1971), Recent Developments ln Thcor:r of Solar Hind, Rev. Geophys. and Space Physics, 9,825-835.

SECCHI, Le P.a., (1875), Early history of eclipses in "Lc Soleil", 2nd ed. Gauthers-Villars, Paris, pp. 330-369.

STamlER, C., (1955), The Polar Aurora, Clarendon Press, Oxford.

van de HULST, H.C., (1953), in The Sun, G.P. Kuiper, Ed., University of Chicago Press, Chicago, p.306.

WALD~mIER, M. (1945)) Mitt. der harg. Natur. Gcs., 22. 185.

YOUNG, C.A. (1896), "The sun", pp. 237-276, Apllcton, New York.