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Pulsar bow-shock nebulae are a class of pulsar wind nebulae (PWNe) that form when the pulsar wind is confined by the ram pressure of the ambient medium, and are usually associated with old pulsars, that have already emerged from the…

Astrophysics · Physics 2009-11-10 N. Bucciantini , E. Amato , L. Del Zanna

We present fully self consistent 3D simulations of compressible Hall MHD plasma that describe spectral features relevant to the solar wind plasma. We find that a $k^{-7/3}$ spectrum sets in for the fluctuations that are smaller than ion…

Space Physics · Physics 2015-05-14 Dastgeer Shaikh , G. P. Zank

Two-dimensional, relativistic, MHD simulations of pulsar-wind powered nebulae provide strong constraints on the properties of the winds themselves. In particular, they confirm that Poynting flux must be converted into particle energy close…

Astrophysics · Physics 2007-05-23 J. G. Kirk

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has observed dozens of millisecond pulsars for over a decade. We have accrued a large collection of dispersion measure (DM) measurements sensitive to the total…

Recently, several new solar radio telescopes have been put into operation and provided spectral-imaging observations with much higher resolutions in decimeter (dm) and centimeter (cm) wavelengths. These telescopes include the Mingantu…

Solar and Stellar Astrophysics · Physics 2023-11-27 Baolin Tan , Yihua Yan , Jing Huang , Yin Zhang , Chengming Tan , Xiaoshuai Zhu

Kinetic plasma theory is used to generate synthetic spacecraft data to analyze and interpret the compressible fluctuations in the inertial range of solar wind turbulence. The kinetic counterparts of the three familiar linear MHD wave…

Space Physics · Physics 2015-06-05 K. G. Klein , G. G. Howes , J. M. TenBarge , S. D. Bale , C. H. K. Chen , C. S. Salem

Identification and characterization of a rapidly increasing number of pulsar wind nebulae is, and will continue to be, a challenge of high-energy gamma-ray astrophysics. Given that such systems constitute -- by far -- the most numerous…

High Energy Astrophysical Phenomena · Physics 2020-05-06 B. Olmi , D. F. Torres

High-precision pulsar timing is highly dependent on precise and accurate modeling of any effects that impact the data. It was shown that commonly used Solar Wind models do not accurately account for variability in the amplitude of the Solar…

By means of self-consistent 3D MHD numerical simulations, we analyze magnetized solar-like stellar winds and their dependence on the plasma-beta parameter. We adopt in our simulations a heating parameter described by gamma, which is…

Solar and Stellar Astrophysics · Physics 2011-02-11 A. A. Vidotto , M. Opher , V. Jatenco-Pereira , T. I. Gombosi

Observations of the Sun in the visible spectral range belong to standard measurements obtained by instruments both on the ground and in the space. Nowadays, both nearly continuous full-disc observations with medium resolution and dedicated…

Solar and Stellar Astrophysics · Physics 2020-06-30 Michal Švanda , Jan Jurčák , David Korda , Jana Kašparová

The sunspot penumbra is a transition zone between the strong vertical magnetic field area (sunspot umbra) and the quiet Sun. The penumbra has a fine filamentary structure that is characterized by magnetic field lines inclined toward the…

Solar and Stellar Astrophysics · Physics 2010-12-02 I. N. Kitiashvili , A. G. Kosovichev , N. N. Mansour , A. A. Wray

Magnetohydrodynamic (MHD) simulations of the solar atmosphere are often performed under the assumption that the plasma is fully ionized. However, in the lower solar atmosphere a reduced temperature often results in only the partial…

Solar and Stellar Astrophysics · Physics 2022-11-09 Conor D. MacBride , David B. Jess , Elena Khomenko , Samuel D. T. Grant

Bright points (BPs) in the solar photosphere are radiative signatures of magnetic elements described by slender flux tubes located in the darker intergranular lanes. They contribute to the ultraviolet (UV) flux variations over the solar…

Solar and Stellar Astrophysics · Physics 2016-08-11 T. L. Riethmüller , S. K. Solanki , S. V. Berdyugina , M. Schüssler , V. Martínez Pillet , A. Feller , A. Gandorfer , J. Hirzberger

Knowledge about the background solar wind plays a crucial role in the framework of space weather forecasting. In-situ measurements of the background solar wind are only available for a few points in the heliosphere where spacecraft are…

Solar and Stellar Astrophysics · Physics 2013-12-05 C. Gressl , A. M. Veronig , M. Temmer , D. Odstrcil , J. A. Linker , Z. Mikic , P. Riley

Accurate forecasting of the solar wind has grown in importance as society becomes increasingly dependent on technology that is susceptible to space weather events. This work describes an inner boundary condition for ambient solar wind…

Space Physics · Physics 2022-07-22 Kaine A. Bunting , Huw Morgan

One of the key challenges in solar and heliospheric physics is to understand the acceleration of the solar wind. As a super-sonic, super-Alfv\'enic plasma flow, the solar wind carries mass, momentum, energy, and angular momentum from the…

Solar and Stellar Astrophysics · Physics 2021-08-11 Daniel Verscharen , Stuart D. Bale , Marco Velli

Recently, new solar model atmospheres have been developed to replace classical 1D LTE hydrostatic models and used to for example derive the solar chemical composition. We aim to test various models against key observational constraints. In…

Solar and Stellar Astrophysics · Physics 2015-06-15 Tiago M. D. Pereira , Martin Asplund , Remo Collet , Irina Thaler , Regner Trampedach , Jorrit Leenaarts

Solar wind forecasting plays a crucial role in space weather prediction, yet significant uncertainties persist due to incomplete magnetic field observations of the Sun. Isolating the solar wind forecasting errors due to these effects is…

The development of the Zeeman-Doppler Imagine (ZDI) technique has provided synoptic observations of surface magnetic fields of low-mass stars. This led the Stellar Astrophysics community to adopt modeling techniques that have been used in…

Solar and Stellar Astrophysics · Physics 2017-02-08 Ofer Cohen

We review current theoretical ideas on pulsar winds and their surrounding nebulae. Relativistic MHD models of the wind of the aligned rotator, and of the striped wind, together with models of magnetic dissipation are discussed. It is shown…

Astrophysics · Physics 2015-06-24 J. G. Kirk , Y. Lyubarsky , J. Petri