Constraints on high-speed solar wind structure near its coronal base: a Ulysses perspective
نویسندگان
چکیده
Ulysses plasma data at high heliographic latitudes were studied to develop constraints on the structure of the corona at the base of the high-speed solar wind. Salient features of the flow poleward of ±60◦ revealed: 1) low variances of all bulk flow parameters, 2) parameter values that agree with those measured during high-speed conditions in the ecliptic plane when all are scaled to 1AU, 3) the continuous presence of two interpenetrating proton streams that are not resolved in velocity space, 4) a single alpha-particle beam that travels at a speed that is close to the local Alfvén speed faster than the primary proton beam, 5) a proton temperature that is a factor of 2.4 times that of the electrons, and 6) a constant helium abundance that averages 4.4% , about half that inferred from helioseismic data in the solar convection zone. These data are combined with a host of other remote-sensing solar data and solar wind data to develop support for a model of a well-mixed solar atmosphere that is driven by reconnection-generated plasma-jet transients. In this model, acceleration of the solar wind to its terminal speed is complete within a heliocentric distance of about 5 Rs.
منابع مشابه
The distribution of solar wind speeds during solar minimum: Calibration for numerical solar wind modeling constraints on the source of the slow solar wind
[1] It took the solar polar passage of Ulysses in the early 1990s to establish the global structure of the solar wind speed during solar minimum. However, it remains unclear if the solar wind is composed of two distinct populations of solar wind from different sources (e.g., closed loops which open up to produce the slow solar wind) or if the fast and slow solar wind rely on the superradial exp...
متن کاملSolar wind ionic charge states during the Ulysses pole - to - pole pass
We analyze and compare the ionic charge composition data for different types of the solar wind (slow wind from equatorial regions, fast wind from low-latitude coronal hole and fast wind from both south and north polar coronal hole) which the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses observed during the pole-to-pole pass of its primary mission. The implications on the electron t...
متن کاملThe Solar Wind : Probing the Heliosphere with Multiple
The combination of the Voyager spacecraft in the outer heliosphere, Ulysses at high latitudes, and multiple solar wind monitors near Earth provides a unique opportunity to study the global structure and evolution of the solar wind. From solar minimum to solar maximum the latitudinal gradients of density and speed reverse so that at solar maximum speeds are higher near the solar equator, but sol...
متن کاملThe Solar Wind : Probing the Heliosphere with Multiple Spacecraft
The combination of the Voyager spacecraft in the outer heliosphere, Ulysses at high latitudes, and multiple solar wind monitors near Earth provides a unique opportunity to study the global structure and evolution of the solar wind. From solar minimum to solar maximum the latitudinal gradients of density and speed reverse so that at solar maximum speeds are higher near the solar equator, but sol...
متن کاملThe solar wind composition throughout the solar cycle: A continuum of dynamic states
[1] Variations in the speed and elemental and ionic charge composition of the solar wind are reported throughout the solar cycle, as observed by the SWICS instrument on Ulysses. The apparent bimodal nature of the solar wind during the solar minimum does not persist throughout the solar cycle. Rather, with increasing solar activity, a continuum of solar wind speeds and charge states is observed....
متن کامل