Evolution of the Solar Wind Speed with Heliocentric Distance and Solar Cycle. Surprises from Ulysses and Unexpectedness from Observations of the Solar Corona
- Авторлар: Khabarova O.1, Obridko V.1, Kislov R.1,2, Malova H.2,3, Bemporad A.4, Zelenyi L.2, Kuznetsov V.1, Kharshiladze A.1
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Мекемелер:
- Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation
- Space Research Institute
- Scobeltsyn Nuclear Physics Institute
- Istituto Nazionale di Astrofisica (INAF)
- Шығарылым: Том 44, № 9 (2018)
- Беттер: 840-853
- Бөлім: Space Plasma
- URL: https://journals.rcsi.science/1063-780X/article/view/186935
- DOI: https://doi.org/10.1134/S1063780X18090064
- ID: 186935
Дәйексөз келтіру
Аннотация
An extensive analysis of Ulysses observations of the solar wind speed V from 1990 to 2008 is undertaken. It is shown that the evolution of V with heliocentric distance r depends substantially on both the heliolatitude and the solar activity cycle. Deviations from the predicted Parker’s profile of V(r) are so considerable that cannot be explained by a scarcity of measurements or other technical effects. In particular, the expected smooth growth of the solar wind speed with r is typical only for the solar activity maximum and for low heliolatitudes (lower than ±40°), while at high latitudes, there are two V(r) branches: growing and falling. In the solar activity maximum, V increases toward the solar pole in the North hemisphere only; however, in the South hemisphere, it decreases with heliolatitude. In the minimum of solar activity, the profile of V(r) at low heliolatitudes has a local minimum between 2 and 5 AU. This result is confirmed by the corresponding data from other spacecraft (Voyager 1 and Pioneer 10). Unexpected spatial variations in V at low heliolatitudes can be explained by the impact of coronal hole flows on the V(r) profile since the flows incline to the ecliptic plane. To reproduce the impact of spatial variations of V in the polar corona on the behavior of V at low heliolatitudes, a stationary one-fluid ideal MHD-model is developed with account of recent results on imagery of the solar wind speed in the corona up to 5.5 solar radii obtained on the basis of combined observations from SOHO/UVCS, LASCO, and Mauna Loa.
Авторлар туралы
O. Khabarova
Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation
Хат алмасуға жауапты Автор.
Email: habarova@izmiran.ru
Ресей, Troitsk, Moscow, 108840
V. Obridko
Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation
Email: habarova@izmiran.ru
Ресей, Troitsk, Moscow, 108840
R. Kislov
Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation; Space Research Institute
Email: habarova@izmiran.ru
Ресей, Troitsk, Moscow, 108840; Moscow, 117997
H. Malova
Space Research Institute; Scobeltsyn Nuclear Physics Institute
Email: habarova@izmiran.ru
Ресей, Moscow, 117997; Moscow, 119234
A. Bemporad
Istituto Nazionale di Astrofisica (INAF)
Email: habarova@izmiran.ru
Италия, Torino, 10025
L. Zelenyi
Space Research Institute
Email: habarova@izmiran.ru
Ресей, Moscow, 117997
V. Kuznetsov
Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation
Email: habarova@izmiran.ru
Ресей, Troitsk, Moscow, 108840
A. Kharshiladze
Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation
Email: habarova@izmiran.ru
Ресей, Troitsk, Moscow, 108840