Authors: Hefti, H. Grünwaldt, F.M. Ipavich, P. Bochsler,
D. Hovestadt, M.R. Aellig, M. Hilchenbach, A.B.
Galvin, J. Geiss, F. Gliem, G. Gloeckler, B. Klecker, E. Marsch,
E. Möbius, M. Neugebauer, and P. Wurz.
Reference: J. Geophys. Res. 103(A12), (1998), 29697-29704.
Abstract:
Using observations of the Charge Time (CTOF) charge and mass
spectrometer of the Charge, Element and Isotope Analysis System
(CELIAS), and of CELIAS/proton monitor on board the Solar Heliospheric
Observatory (SOHO), we present an overview of speeds and kinetic
temperatures of minor ions and protons in the solar wind near solar
minimum, covering the Carrington Rotations 1908 to 1912. In the case of
a collision-dominated solar wind the speed of minor ions is expected to
have equal temperatures. On the other hand, minor ions can be
accelerated and heated by wave-particle interaction. In this case,
equal thermal speeds of all species are expected. CTOF data allow the
determination of the kinetic parameters of various ions with high
accuracy and with high time resolution. The mean O6+ speed
of the observed period is 390 km s-1 . The speeds of
Si7+ and Fe9+ correlate well with
O6+,, the linear correlation coefficient being 0.96 or
higher. Our results also indicate that silicon and iron then to lag
behind oxygen with a speed difference of ~ 20 km s-1 at
500 km s-1. At the same time, the kinetic temperature of the
ions under investigation exhibit the well-known mass proportionality,
which is attributed to wave-particle interactions. During the period of
low solar activity in consideration, many cases are observed where the
kinetic temperature is extraordinarily low (104 K for O6+).