@article{Verscharen:2021:0004-6361/202140956,
author = {Verscharen, D and Stansby, D and Finley, AJ and Owen, CJ and Horbury, T and Maksimovic, M and Velli, M and Bale, SD and Louarn, P and Fedorov, A and Bruno, R and Livi, S and Khotyaintsev, Y and Vecchio, A and Lewis, GR and Anekallu, C and Kelly, CW and Watson, G and Kataria, DO and O'Brien, H and Evans, V and Angelini, V},
doi = {0004-6361/202140956},
journal = {Astronomy and Astrophysics: a European journal},
pages = {1--10},
title = {The angular-momentum flux in the solar wind observed during Solar Orbiter's first orbit},
url = {http://dx.doi.org/10.1051/0004-6361/202140956},
volume = {656},
year = {2021}
}

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TY  - JOUR
AB  - Aims. We present the first measurements of the angular-momentum flux in the solar wind recorded by the Solar Orbiter spacecraft. Our aim is to validate these measurements to support future studies of the Sun’s angular-momentum loss.Methods. We combined 60-min averages of the proton bulk moments and the magnetic field measured by the Solar Wind Analyser and the magnetometer onboard Solar Orbiter. We calculated the angular-momentum flux per solid-angle element using data from the first orbit of the mission’s cruise phase in 2020. We separated the contributions from protons and from magnetic stresses to the total angular-momentum flux.Results. The angular-momentum flux varies significantly over time. The particle contribution typically dominates over the magnetic-field contribution during our measurement interval. The total angular-momentum flux shows the largest variation and is typically anti-correlated with the radial solar-wind speed. We identify a compression region, potentially associated with a co-rotating interaction region or a coronal mass ejection, which leads to a significant localised increase in the angular-momentum flux, albeit without a significant increase in the angular momentum per unit mass. We repeated our analysis using the density estimate from the Radio and Plasma Waves instrument. Using this independent method, we find a decrease in the peaks of positive angular-momentum flux, but otherwise, our results remain consistent.Conclusions. Our results largely agree with previous measurements of the solar wind’s angular-momentum flux in terms of amplitude, variability, and dependence on radial solar-wind bulk speed. Our analysis highlights the potential for more detailed future studies of the solar wind’s angular momentum and its other large-scale properties with data from Solar Orbiter. We emphasise the need for studying the radial evolution and latitudinal dependence of the angular-momentum flux in combination with data from
AU  - Verscharen,D
AU  - Stansby,D
AU  - Finley,AJ
AU  - Owen,CJ
AU  - Horbury,T
AU  - Maksimovic,M
AU  - Velli,M
AU  - Bale,SD
AU  - Louarn,P
AU  - Fedorov,A
AU  - Bruno,R
AU  - Livi,S
AU  - Khotyaintsev,Y
AU  - Vecchio,A
AU  - Lewis,GR
AU  - Anekallu,C
AU  - Kelly,CW
AU  - Watson,G
AU  - Kataria,DO
AU  - O'Brien,H
AU  - Evans,V
AU  - Angelini,V
DO  - 0004-6361/202140956
EP  - 10
PY  - 2021///
SN  - 0004-6361
SP  - 1
TI  - The angular-momentum flux in the solar wind observed during Solar Orbiter's first orbit
T2  - Astronomy and Astrophysics: a European journal
UR  - http://dx.doi.org/10.1051/0004-6361/202140956
UR  - https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000730246400025&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://www.aanda.org/articles/aa/full_html/2021/12/aa40956-21/aa40956-21.html
UR  - http://hdl.handle.net/10044/1/99039
VL  - 656
ER  - 

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