Acceleration of the High Speed Solar Wind in Coronal Holes

Axford, W. I.; McKenzie, J. F.; Sukhorukova, G. V.; Banaszkiewicz, M.; Czechowski, A.; Ratkiewicz, R.

doi:10.1007/978-94-015-9167-6_2

Cited by 9 publications

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“…This rapid acceleration was confirmed by IPS observations made using the EISCAT (932 MHz) and MERLIN (5 GHz) facilities by Breen et al [2000, 2002]. Closer to the Sun, the Solar and Heliospheric Observatory (SOHO) spacecraft observed the acceleration of the fast solar wind taking place within several solar radii [ Kohl et al , 1998; Axford et al , 1999; Cranmer et al , 1999; Breen et al , 2000; Giordano et al , 2000; Patsourakos and Vial , 2000; Miralles et al , 2001; Breen et al , 2002; Teriaca et al , 2003]. These observations revealed that the fast solar wind attains 50% of its cruising speed by 4–5 R s and the acceleration is almost completed inside 10 R s .…”

Section: Introductionmentioning

confidence: 82%

Fast solar wind after the rapid acceleration

et al. 2004

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[1] We have studied the radial dependence of the velocity of high-latitude fast solar wind in the heliocentric distance range of 0.13-0.9 AU. For this study a new tomographic analysis method which can evaluate uncertainties was developed to obtain velocity distribution maps on two reference spheres at 0.13 and 0.3 AU using interplanetary scintillation (IPS) observations. First of all, it is tested that this tomographic method has enough sensitivity and reliability to investigate the radial dependence of the wind velocity. The analysis was made for the IPS observations during 3 years, from 1995 to 1997, when solar activity was minimum. From this analysis, average velocities of 770-780 km s À1 were obtained at distances of 0.13-0.3 AU, which were 19 ± 17 km s À1 lower than those at 0.3-0.9 AU. The results from this work, taken together with measurements of SOHO/ LASCO, EISCAT and MERLIN [Breen et al., 2002], Helios [Schwenn et al., 1978], and Ulysses [McComas et al., 2000], indicate that the fast wind is accelerated almost to its final flow velocity within 20 R s and a small but not negligible acceleration exists beyond 30 R s which tends to become smaller at farther heliocentric distances.

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Section: Introductionmentioning

confidence: 82%

Fast solar wind after the rapid acceleration

et al. 2004

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“…Does it occur especially at cell-network boundaries (Axford et al, 1999) or higher in the transition region or even in the corona?…”

Section: Magnetic Reconnection and Its Various Manifestationsmentioning

confidence: 98%

“…2 derived from GabrielÕs initial model of 1976 (Axford et al, 1999). The evolution from GabrielÕs static model (left) to a dynamic model with reconnection (right) conveys that a stationary model is not valid and that one must take into account the dynamics of small-scale events occurring in the network.…”

Section: The Current View Of the Sunmentioning

confidence: 98%

“…According to Axford et al (1999), the emergence leads to magnetic reconnection with many possible manifestations: flows, jets, field rearrangement, plasma heating, current filamentation, particles acceleration, and wave generation (high-frequency MHD).…”

Section: Interaction With the Chromospheric Networkmentioning

confidence: 99%

“…Classical model of the magnetic structuring from the convection zone to the corona (taken fromAxford et al (1999) and APR). It shows the evolution from GabrielÕs static model (left) to a dynamic model with reconnection (right).…”

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The plasma structure of coronal hole solar wind: Origins and evolution

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Whereas slow solar wind is known to be highly structured, the fast (coronal hole origin) wind is usually considered to be homogeneous. Using measurements from Helios 1 + 2, ACE, Wind, and Ulysses, structure in the coronal hole origin solar wind is examined from 0.3 AU to 2.3 AU. Care is taken to collect and analyze intervals of “unperturbed coronal hole plasma.” In these intervals, solar wind structure is seen in the proton number density, proton temperature, proton specific entropy, magnetic field strength, magnetic field to density ratio, electron heat flux, helium abundance, heavy‐ion charge‐state ratios, and Alfvenicity. Typical structure amplitudes are factors of 2, far from homogeneous. Variations are also seen in the solar wind radial velocity. Using estimates of the motion of the solar wind origin footpoint on the Sun for the various spacecraft, the satellite time series measurements are converted to distance along the photosphere. Typical variation scale lengths for the solar wind structure are several variations per supergranule. The structure amplitude and structure scale sizes do not evolve with distance from the Sun from 0.3 to 2.3 AU. An argument is quantified that these variations are the scale expected for solar wind production in open magnetic flux funnels in coronal holes. Additionally, a population of magnetic field foldings (switchbacks, reversals) in the coronal hole plasma is examined: this population evolves with distance from the Sun such that the magnetic field is mostly Parker spiral aligned at 0.3 AU and becomes more misaligned with distance outward.

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Acceleration of the High Speed Solar Wind in Coronal Holes

Cited by 9 publications

References 0 publications

Fast solar wind after the rapid acceleration

Fast solar wind after the rapid acceleration

Solar Orbiter: A unique opportunity for investigating small-scale physical processes at work in the magnetic solar atmosphere

The plasma structure of coronal hole solar wind: Origins and evolution

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