Article
Astronomy & Astrophysics
Patrick Hennebelle
Summary: This paper investigates the role of turbulence in the formation of astrophysical structures through 3D and 1D simulations, providing insights into turbulence behavior and dissipation parameters during collapse. The results show that turbulence amplification or generation depends on the cloud's thermal support, with implications for understanding gravitational collapse dynamics.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Madeleine Stewart, Christoph Federrath
Summary: The structure and star formation activity of a molecular cloud are closely related to its internal turbulence. This study develops a new method to accurately measure the turbulent velocity dispersion of a molecular cloud, taking into account the gradient correction. The results show that with the suitable correction factor and appropriate filters, the 3D turbulent velocity dispersion can be recovered, which is crucial for understanding the dynamics of molecular clouds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Glen H. Hunter, Paul C. Clark, Simon C. O. Glover, Ralf S. Klessen
Summary: In this study, the impact of collision speed, magnetic field inclination, and resolution on the star formation rate (SFR) in cloud-cloud collisions is investigated. A factor of 2-3 increase in the SFR is found compared to no collision simulations, with high collisional velocities, parallel magnetic field and collision axis orientation, and lower resolution leading to earlier star formation. The alignment of velocity and magnetic field is consistent in low-density environments but becomes more perpendicular as density increases, indicating the compression of the magnetic field by collapsing gas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Lars Mattsson, Robert Hedvall
Summary: The dynamics of interstellar dust particles in forced compressible transonic turbulence simulations were investigated, showing that self-gravity can significantly accelerate large grains and increase clustering for intermediate-sized grains. This suggests that self-gravity effects can play a crucial role in dust aggregation/coagulation even in non-Jeans-unstable turbulent systems.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
F. Fontani, A. Schmiedeke, A. Sanchez-Monge, L. Colzi, D. Elia, V. M. Rivilla, M. T. Beltran, L. Bizzocchi, P. Caselli, L. Magrini, D. Romano
Summary: The study reveals that the chemical properties of the outer star-forming regions of the Galaxy are similar to those of the inner and local regions. Methanol (CH3OH) is detected in the observed targets, and its emission is associated with an extended envelope, indicating that it mainly comes from a cold and quiescent region. The relative abundance of CH3OH shows good correlations with that of H2CO, but not with HCO. These findings have significant implications for understanding the organic and possibly pre-biotic chemistry in the outermost star-forming regions of the Galaxy.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
F. D. Priestley, P. C. Clark, S. C. O. Glover, S. E. Ragan, O. Feher, L. R. Prole, R. S. Klessen
Summary: The study finds that molecular species commonly assumed to trace the dense, star-forming component of molecular clouds actually exist in material transiently enhanced in density. Only N2H+ exists in detectable quantities above a certain volume density, and N2H+ emission can be used to predict star formation in molecular clouds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Michael Y. Grudic, David Guszejnov, Philip F. Hopkins, Stella S. R. Offner, Claude-Andre Faucher-Giguere
Summary: STARFORGE is a new numerical framework for 3D radiation magnetohydrodynamic simulations of star formation, incorporating various stellar feedback mechanisms. It utilizes advanced algorithms and methods to accurately model the formation, evolution, and dynamics of individual stars in massive giant molecular clouds. The model has been shown to scale up to massive GMCs on current supercomputers while accurately predicting the stellar range of the IMF.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
David J. Whitworth, Rowan J. Smith, Ralf S. Klessen, Mordecai-Mark Mac Low, Simon C. O. Glover, Robin Tress, Ruediger Pakmor, Juan D. Soler
Summary: Many studies have shown that magnetic fields can suppress star formation in molecular clouds and Milky Way like galaxies. However, most of these studies have focused on fully developed fields at saturation level, and there is little understanding of how weak initial primordial fields affect star formation in low metallicity environments. In this paper, the impact of a weak initial field on low metallicity dwarf galaxies is investigated. High-resolution AREPO simulations are performed, and the results show that the magnetic field has little impact on the global star formation rate (SFR), contrary to some previous studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Philipp Girichidis, Thorsten Naab, Stefanie Walch, Thomas Berlok
Summary: Molecular outflows in star-forming galaxies are observed in small and large systems at low and high redshift, but their physical origin is still unclear. High-resolution simulations show that a magnetized wind may trigger H-2 formation in clouds with densities greater than 0.5 cm(-3), converting up to 3% of the initial cloud mass into molecular gas before dispersal.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Patrick Hennebelle, Ugo Lebreuilly, Tine Colman, Davide Elia, Gary Fuller, Silvia Leurini, Thomas Nony, Eugenio Schisano, Juan D. Soler, Alessio Traficante, Ralf S. Klessen, Sergio Molinari, Leonardo Testi
Summary: The physical origin of the stellar initial mass function (IMF) remains a subject of debate despite decades of theoretical efforts. This study aimed to understand the influence of various physical processes on the IMF, including radiative stellar feedback, magnetic fields, and non-ideal magneto-hydrodynamics. Numerical simulations were conducted with different scenarios, and analytical models were compared with the results. The study found that the combination of magnetic field and radiative feedback significantly impacts the stellar mass spectrum, reducing fragmentation and leading to the formation of more massive stars.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Nirmit Sakre, Asao Habe, Alex R. Pettitt, Takashi Okamoto, Rei Enokiya, Yasuo Fukui, Takashi Hosokawa
Summary: In this study, the effects of magnetic fields on the formation of massive, self-gravitationally bound cores (MBCs) in high-speed cloud-cloud collisions (CCCs) are investigated through magnetohydrodynamic simulations. The results show that magnetic fields hinder the growth of cores, especially in short-duration collisions. This two-fold effect of magnetic fields on the MBC formation in CCCs results in a maximum collision speed for the formation of massive stars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. M. Kupilas, C. J. Wareing, J. M. Pittard, S. A. E. G. Falle
Summary: In this study, hydrodynamic simulations of shock interaction with evolving molecular clouds due to thermal instability and gravity were conducted using the adaptive mesh refinement code mg. Three case studies were presented to explore the relative importance of these processes. The results indicate that shocks accelerate the global collapse of the clouds while local gravitational collapses occur both before and after the formation of the molecular clouds. Different stages of cloud evolution are dominated by different processes, providing realistic conditions for future feedback studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Jacob L. Ward, J. M. Diederik Kruijssen, Melanie Chevance, Jaeyeon Kim, Steven N. Longmore
Summary: This paper aims to study the lifecycle of molecular clouds in the Large Magellanic Cloud (LMC) and determines their lifetime to be around 11.8 million years. The study finds that molecular clouds in the LMC are decoupled from galactic dynamics and have short lifetimes regulated by internal processes, while atomic clouds are correlated with galactic dynamical timescales.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. M. Kupilas, C. J. Wareing, J. M. Pittard, S. A. E. G. Falle
Summary: In this study, hydrodynamic simulations were performed using the adaptive mesh refinement code mg to investigate the interaction of a shock with a molecular cloud. Three case studies were presented to explore the importance of thermal instability and gravity processes. The evolution is shock dominated when the cloud is still atomic, while the post-shock flow is directed through pre-existing structures when the cloud is molecular, accelerating clump-clump collisions and mergers. The clouds in this study provide realistic conditions for future feedback studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Wenrui Xu, Matthew W. Kunz
Summary: In this study, the formation and early evolution of a protostellar disc from a magnetized prestellar core are investigated using non-ideal MHD simulations. The results indicate that gravitational instability plays a key role in the spreading of the disc structure and the redistribution of angular momentum within the protostar-disc system. These findings help to explain some important processes in the evolution of protostellar discs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Alex Debrecht, Jonathan Carroll-Nellenback, Adam Frank, Eric G. Blackman, Luca Fossati, John McCann, Ruth Murray-Clay
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
Luke Chamandy, Eric G. Blackman, Adam Frank, Jonathan Carroll-Nellenback, Yisheng Tu
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
Yangyuxin Zou, Adam Frank, Zhuo Chen, Thomas Reichardt, Orsola De Marco, Eric G. Blackman, Jason Nordhaus, Bruce Balick, Jonathan Carroll-Nellenback, Luke Chamandy, Baowei Liu
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
David Kipping, Adam Frank, Caleb Scharf
INTERNATIONAL JOURNAL OF ASTROBIOLOGY
(2020)
Article
Astronomy & Astrophysics
R. N. Markwick, A. Frank, J. Carroll-Nellenback, B. Liu, E. G. Blackman, S. Lebedev, P. M. Hartigan
Summary: Hydrodynamic simulations using AstroBEAR AMR code show that radiative cooling can significantly influence the structure of shocks in colliding protostellar jets, potentially leading to radiative shock instability and nonlinear thin shell instability. Cooling length variations oscillate the size of the cooling region, affecting the onset and behavior of these instabilities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Physics, Multidisciplinary
A. Lees, R. Betti, J. P. Knauer, V. Gopalaswamy, D. Patel, K. M. Woo, K. S. Anderson, E. M. Campbell, D. Cao, J. Carroll-Nellenback, R. Epstein, C. Forrest, V. N. Goncharov, D. R. Harding, S. X. Hu, I. V. Igumenshchev, R. T. Janezic, O. M. Mannion, P. B. Radha, S. P. Regan, A. Shvydky, R. C. Shah, W. T. Shmayda, C. Stoeckl, W. Theobald, C. Thomas
Summary: Statistical modeling has improved predictive capability for deuterium-tritium layered cryogenic implosions at the OMEGA laser, revealing dependencies of fusion yield and identifying degradation mechanisms. Adjusted for factors like tritium decay and l = 1 mode, the highest predicted yield in OMEGA cryogenic implosions exceeds 2 x 10^14 fusion reactions.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Ethan Savitch, Adam Frank, Jonathan Carroll-Nellenback, Jacob Haqq-Misra, Axel Kleidon, Marina Alberti
Summary: This passage discusses modeling the evolution of a civilization and its host planet, examining the impact of energy harvesting on the planet's climate and the possibility of triggering Anthropocenes. Climate sensitivity is highlighted as a key parameter influencing the fate of a civilization in this context.
ASTRONOMICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Atma Anand, Jonathan Carroll-Nellenback, Eric G. Blackman, John A. Tarduno
Summary: Magnetic fields are important for understanding the thermal, material, and structural history of planetary and sub-planetary bodies. This study explores how the stellar wind can amplify magnetic fields in initially unmagnetized bodies, finding a broadly applicable scaling relation and discussing the saturation of magnetic fields. The research highlights that denser and faster winds lead to stronger amplification of magnetic fields.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Physics, Multidisciplinary
Damian Radoslaw Sowinski, Jonathan Carroll-Nellenback, Jeremy DeSilva, Adam Frank, Gourab Ghoshal, Marcelo Gleiser
Summary: Agents interacting with their environments make decisions based on their limited access to data and cognitive limitations, leading to different conclusions and actions. This has a significant impact on polities based on information sharing and can result in a consensus problem.
Article
Physics, Fluids & Plasmas
R. N. Markwick, A. Frank, J. Carroll-Nellenback, E. G. Blackman, P. M. Hartigan, S. V. Lebedev, D. R. Russell, J. W. D. Halliday, L. G. Suttle
Summary: By simulating and studying the bow shock formed by the collision of hypersonic flows, it is found that the motion of the interaction region is driven by imbalances in ram pressure between the two flows, and the conical structure of the bow shock is a result of deflected lateral outflows when the flows have differing cross sections.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Multidisciplinary
D. R. Russell, G. C. Burdiak, J. J. Carroll-Nellenback, J. W. D. Halliday, J. D. Hare, S. Merlini, L. G. Suttle, V. Valenzuela-Villaseca, S. J. Eardley, J. A. Fullalove, G. C. Rowland, R. A. Smith, A. Frank, P. Hartigan, A. L. Velikovich, J. P. Chittenden, S. V. Lebedev
Summary: This study presents the investigation of perpendicular subcritical shocks in a collisional laboratory plasma. The shocks are generated by placing obstacles in the supermagnetosonic outflow from an inverse wire array z pinch. The existence of subcritical shocks in this regime is demonstrated, and it is found that secondary shocks form in the downstream. Detailed measurements confirm the absence of a hydrodynamic jump in the subcritical shock structure. The calculated resistive diffusion length is approximately equal to the shock width. Little heating is observed across the shock, indicating a lack of viscous dissipation.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Fluids & Plasmas
A. Lees, R. Betti, J. P. Knauer, V. Gopalaswamy, D. Patel, K. M. Woo, K. S. Anderson, E. M. Campbell, D. Cao, J. Carroll-Nellenback, R. Epstein, C. J. Forrest, V. N. Goncharov, D. R. Harding, S. X. Hu, I. V. Igumenshchev, R. T. Janezic, O. M. Mannion, P. B. Radha, S. P. Regan, A. Shvydky, R. C. Shah, W. T. Shmayda, C. Stoeckl, W. Theobald, C. A. Thomas
Summary: A physics-based statistical mapping approach was used to extract and quantify the major sources of degradation of fusion yield in direct-drive implosions on the OMEGA laser. The yield was found to be dependent on the age of the fill, implosion core asymmetry, laser beam-to-target size ratio, and hydrodynamic stability parameters. A new implosion design was created, guided by the mapping model, resulting in increased fusion yield in targets with larger diameters.
PHYSICS OF PLASMAS
(2023)
Article
Physics, Fluids & Plasmas
Hannah R. Hasson, Marissa B. Adams, Matthew Evans, Roman V. Shapovalov, Imani West-Abdallah, James Young, John Greenly, David Hammer, Bruce Kusse, Charles Seyler, Adam Frank, Pierre-Alexandre Gourdain
IEEE TRANSACTIONS ON PLASMA SCIENCE
(2020)
Article
Astronomy & Astrophysics
Joel H. Kastner, Jesse Bublitz, Bruce Balick, Rodolfo Montez, Adam Frank, Eric Blackman
Article
Astronomy & Astrophysics
Bruce Balick, Adam Frank, Baowei Liu
ASTROPHYSICAL JOURNAL
(2020)