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{Filaments are ubiquitous in the interstellar medium as recently emphasized by Herschel, yet their physical origin remains elusive} {It is therefore important to understand the physics of molecular clouds to investigate how filaments form…

Astrophysics of Galaxies · Physics 2015-06-16 Patrick Hennebelle

New extragalactic measurements of the cloud population-averaged star formation (SF) efficiency per freefall time $\rm\epsilon_{\rm ff}$ from PHANGS show little sign of theoretically predicted dependencies on cloud-scale virial level or…

Interplanetary coronal mass ejections (ICMEs) contain magnetic field and velocity fluctuations across a wide range of scales. These fluctuations may be interpreted as Alfv\'enic wave packets propagating parallel or anti-parallel to the…

Space Physics · Physics 2022-05-23 S. W. Good , L. M. Hatakka , M. Ala-Lahti , J. E. Soljento , A. Osmane , E. K. J. Kilpua

Velocity anisotropy induced by MHD turbulence is investigated using computational simulations and molecular line observations of the Taurus molecular cloud. A new analysis method is presented to evaluate the degree and angle of velocity…

Astrophysics · Physics 2009-11-13 Mark Heyer , Hao Gong , Eve Ostriker , Christopher Brunt

The three-dimensional characterization of magnetic flux-ropes observed in the heliosphere has been a challenging task for decades. This is mainly due to the limitation to infer the 3D global topology and the physical properties from the 1D…

Solar and Stellar Astrophysics · Physics 2023-05-03 Teresa Nieves-Chinchilla , Miguel Angel Hidalgo , Hebe Cremades

Solar active regions and sunspots are believed to be formed by the emergence of strong toroidal magnetic flux from the solar interior. Modeling of such events has focused on the dynamics of compact magnetic entities, colloquially known as…

Solar and Stellar Astrophysics · Physics 2021-03-17 Bhishek Manek , Nicholas Brummell

n order to better understand the solar genesis of interplanetary magnetic clouds (MCs) we model the magnetic and topological properties of four large eruptive solar flares and relate them to observations. We use the three-dimensional…

Solar and Stellar Astrophysics · Physics 2015-05-27 Maria D. Kazachenko , Richard C. Canfield , Dana W. Longcope , Jiong Qiu

We propose to perform mean-field variational inference (MFVI) in a rotated coordinate system that reduces correlations between variables. The rotation is determined by principal component analysis (PCA) of a cross-covariance matrix…

Computation · Statistics 2025-10-10 Yifan Chen , Sifan Liu

We investigate the transition of the solar wind turbulent cascade from MHD to sub-ion range by means of a detail comparison between in situ observations and hybrid numerical simulations. In particular we focus on the properties of the…

Space Physics · Physics 2020-09-01 L. Matteini , L. Franci , O. Alexandrova , C. Lacombe , S. Landi , P. Hellinger , E. Papini , A. Verdini

We investigate analytically the magnetic instability in a rotating and electrically conducting fluid induced by an imposed magnetic field with its associated electric current. The short-wavelength approximation is used in the linear…

Earth and Planetary Astrophysics · Physics 2013-08-22 Xing Wei

(abridged) We review methods for measuring the sizes, line widths, and luminosities of giant molecular clouds (GMCs) in molecular-line data cubes with low resolution and sensitivity. We find that moment methods are robust and sensitive --…

Astrophysics · Physics 2008-11-26 Erik Rosolowsky , Adam Leroy

Using multi-viewpoint observations from STEREO and SOHO during three solar cycles from 23 to 25, we study the magnetic flux rope (MFR) structures of coronal mass ejections (CMEs) near the Sun and magnetic clouds (MCs) at 1au. The study aims…

Solar and Stellar Astrophysics · Physics 2025-01-08 Hong Xie , Nat Gopalswamy , Sachiko Akiyama , Pertti Makela , Seiji Yashiro

As most of the modern astronomical sky surveys produce data faster than humans can analyze it, Machine Learning (ML) has become a central tool in Astronomy. Modern ML methods can be characterized as highly resistant to some experimental…

Instrumentation and Methods for Astrophysics · Physics 2021-09-01 J. B. Cabral , M. Lares , S. Gurovich , D. Minniti , P. M. Granitto

The linear stability of global non-axisymmetric modes in differentially rotating, magnetized, non-ideal plasma is crucial for understanding turbulence and transport phenomena. We investigate the competition between the local…

High Energy Astrophysical Phenomena · Physics 2025-11-18 Alexander Haywood , Fatima Ebrahimi

Galaxy distances and derived radial peculiar velocity catalogs constitute valuable datasets to study the dynamics of the Local Universe. However, such catalogs suffer from biases whose effects increase with the distance. Malmquist biases…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Jenny G. Sorce

For the past 30+ years, the magnetic expansion factor ($f_s$) has been used in empirical relationships to predict solar wind speed ($v_{obs}$) at 1 AU, based on an inverse relationship between these two quantities. Coronal unipolar…

Solar and Stellar Astrophysics · Physics 2020-08-03 Samantha Wallace , Charles N. Arge , Nicholeen M. Viall , Ylva Pihlstrom

Magnetic turbulence is anisotropic as the directions of motion are constrained by the magnetic field. Such anisotropy can be observed in velocity centroids obtained from spectroscopic observations. We use magnetohydrodynamics (MHD)…

Astrophysics of Galaxies · Physics 2020-08-13 D. Hernández-Padilla , A. Esquivel , A. Lazarian , D. Pogosyan , D. Kandel , J. Cho

Over the last few years, numerical models of the behavior of solar magnetic flux tubes have gone from using methods that were essentially one-dimensional (i.e. the thin flux tube approximation), over more or less idealized two-dimensional…

Astrophysics · Physics 2007-05-23 Bertil Dorch

Multi-fidelity Monte Carlo (MFMC) is a variance reduction method that leverages a multi-fidelity ensemble of models of varying cost and accuracy levels. Constructing an MFMC estimator with optimal variance requires knowledge of the…

Methodology · Statistics 2026-05-25 Michael Stanley , Thomas Coons , Geoffrey Bomarito , Patrick Leser , Joshua Pribe , James Warner

Much of our understanding of modern astrophysics rest on the notion that the Initial Mass Function (IMF) is universal. Our observations of a sample of HI-selected galaxies in the light of H-alpha and the far-ultraviolet (FUV) challenge this…

Cosmology and Nongalactic Astrophysics · Physics 2010-08-25 G. R. Meurer