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Related papers: Long-Term Trends In The Solar Wind Proton Measurem…

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In a previous paper, we found that proton temperatures are clearly associated with the proton-scale turbulence in the solar wind, and magnetic helicity signature appears to be an important indicator in the association. Based on 15 years of…

Space Physics · Physics 2021-01-27 G. Q. Zhao , Y. Lin , X. Y. Wang , H. Q. Feng , D. J. Wu , H. B. Li , A. Zhao , Q. Liu

Stochastic heating is a non-linear heating mechanism driven by the violation of magnetic moment invariance due to large-amplitude turbulent fluctuations producing diffusion of ions towards higher kinetic energies in the direction…

High speed solar wind streams (HSSs) are very efficient drivers of geomagnetic activity at high latitudes. In this paper we use a recently developed $\Delta{H}$ parameter of geomagnetic activity, calculated from the night-side hourly…

Space Physics · Physics 2017-05-03 Renata Lukianova , Lauri Holappa , Kalevi Mursula

We present an analysis of the components of solar wind proton temperature perpendicular and parallel to the local magnetic field as a function of proximity to plasma instability thresholds. We find that $T_{\perp p}$ is enhanced near the…

Solar and Stellar Astrophysics · Physics 2009-11-17 J. C. Kasper , B. A. Maruca , S. D. Bale

Parker Solar Probe (PSP) observations have revealed that most of the solar wind acceleration occurs very close to the Sun. This acceleration is partly due to the global electric potential originating from the mass disparity between…

Solar and Stellar Astrophysics · Physics 2025-05-14 Maximilien Péters de Bonhome , Viviane Pierrard , Fabio Bacchini

We update the SOHO/SWAN H Lyman-alpha brightness analysis to cover the 1996-2008 time interval. A forward model applied to the intensity maps provides the latitude and time dependence of the interstellar Hydrogen ionisation rate over more…

Solar and Stellar Astrophysics · Physics 2010-03-23 Rosine Lallement , Eric Quemerais , Philippe Lamy , Jean-Loup Bertaux , Stephane Ferron , Walter Schmidt

Interplanetary (IP) shocks efficiently modify the proton temperature anisotropy of the solar wind. Analyzing ~800 IP shocks observed by the Wind spacecraft from 1997-2024, we present a statistical study of upstream and downstream proton…

The properties of the solar wind measured in-situ in the heliosphere are largely controlled by energy deposition in the solar. Previous studies have shown that long duration and large scale magnetic structures show an inverse relation…

Solar and Stellar Astrophysics · Physics 2024-10-30 J-B. Dakeyo , A. P. Rouillard , V. Réville , P. Démoulin , M. Maksimovic , A. Chapiron , R. F. Pinto , P. Louarn

It is known that the tilt angles of active regions increase with their latitude (Joy's law). It has never been checked before, however, whether the average tilt angles change from one cycle to another. Flux transport models show the…

Solar and Stellar Astrophysics · Physics 2015-05-18 Maria Dasi-Espuig , Sami K. Solanki , Natasha A. Krivova , Robert H. Cameron , Tania Peñuela

In solar cycles 23-24, solar activity noticeably decreased, and, as a result, solar wind parameters decreased. Based on the measurements of the OMNI base for the period 1976-2019, the time profiles of the main solar wind parameters and…

We present a new catalogue of solar energetic particle events near the Earth, covering solar cycle 23 and the majority of solar cycle 24 (1996-2016), based on the 55-80 MeV proton intensity data gathered by the SOHO/ERNE experiment. In…

The composite geometry and spectral anisotropy of the solar wind turbulence are very important topics in the investigations of solar wind. In this work, we use the magnetic field and plasma data from Wind spacecraft measured during 1995…

Space Physics · Physics 2025-05-20 Zhan Fa , H. -Q. He

Context. The relation between solar surface rotation and sunspot activity still remains open. Sunspot activity has dramatically reduced in solar cycle 24 and several solar activity indices and flux measurements experienced unprecedentedly…

Solar and Stellar Astrophysics · Physics 2015-02-18 L. Zhang , K. Mursula , I. Usoskin

Using data collected by the Indian Mars Orbiter Mission in October 2021, we investigated coronal regions of the Sun by analyzing the Doppler spectral width of radio signals to estimate solar wind velocity. A simplified equation is…

Solar and Stellar Astrophysics · Physics 2025-04-02 Keshav Aggarwal , R. K. Choudhary , Abhirup Datta , Roopa M. V. , Bijoy K. Dai

The Quasi-thermal noise (QTN) technique is a reliable tool to yield accurate measurements of the electron parameters in the solar wind. We apply this method on Parker Solar Probe (PSP) observations to derive the total electron temperature…

In the lower solar coronal regions where the magnetic field is dominant, the Alfven speed is much higher than the wind speed. In contrast, the near-Earth solar wind is strongly super-Alfvenic, i.e., the wind speed greatly exceeds the Alfven…

Alfv\'enicity is a well-known property, common in the solar wind, characterized by a high correlation between magnetic and velocity fluctuations. Data from the Parker Solar Probe (PSP) enable the study of this property closer to the Sun…

The Earth's magnetosphere extension is controlled by the solar activity level via solar wind properties. Understanding such a relation in the Solar System is important for predicting also the condition of exoplanetary magnetospheres near…

According to \emph{Wind} observations between June 2004 and May 2019, this Letter investigates the proton and alpha particle temperatures in the space of ($\theta_d$, $V_d/V_A$) for the first time, where $\theta_d$ and $V_d$ are the radial…

Space Physics · Physics 2020-02-05 G. Q. Zhao , H. Q. Feng , D. J. Wu , J. Huang , Y. Zhao , Q. Liu , Z. J. Tian

Measurements from the Mount Wilson Observatory (MWO) are used to study the long-term variations of sunspot field strengths from 1920 to 1958. Following a modified approach similar to that in Pevtsov et al. (2011), for each observing week we…

Solar and Stellar Astrophysics · Physics 2013-01-28 Alexei A. Pevtsov , Luca Bertello , Andrey G. Tlatov , Ali Kilcik , Yury A. Nagovitsyn , Edward W. Cliver