![]() |
Figure 3 |
[18] The general characteristics of the heliosphere, its dimensions, the form of the main surfaces, etc., depend heavily on the properties of the very local interstellar medium, surrounding the heliosphere in the Galaxy. Consequently many properties of the near-Earth space would be quite different from the present ones if the Sun were a trifle off its present position, the fact often forgotten in formulating the list of the cosmic factors important for the Earth. Figure 3 from Bochkarev [1990] illustrates the position of the Sun with respect to the Scorpion-Centaurs (SCO-CEN) stellar association which center is
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Figure 4 |
[19] We shall not go into detail
[see Bochkarev, 1990],
just mention
that now the Sun is in the worm (temperature
T 104 K)
and rather rare
(density
n
10-1 cm
-1 )
weakly ionized hydrogen, the heliospheric
dimensions being about 200 AU. If the Sun shifted to the SCO-CEN
association by about 10-20 Pc (compare with the 10 kPc distance
from the center of the Galaxy!) it would be surrounded by 2 order of
magnitude denser and colder hydrogen and there is even a possibility
that the whole heliosphere could be inside the Earth's orbit, and the
Earth would be without any solar wind, the solar cycle and other GCR
variations etc.! If somebody shifted the Sun 10-20 Pc more it would
be in the SCO-CEN cavity with highly rarefied
( n
10-3 cm
-1 ) and hot
( T
106 K) gas and the dimensions of the heliosphere could be much
greater than now. Then the phase shift of the solar cycle in the inner
and outer parts of the heliosphere would be great and the solar cycle in
the GCR intensity would look quite different from how it looks now
[see Krainev and Webber, 2004].
Citation: 2004), Main phases of the solar cycle in the galactic cosmic ray intensity, Int. J. Geomagn. Aeron., 5, GI2004, doi:10.1029/2004GI000070.
Copyright 2004 by the American Geophysical Union (