Article
Astronomy & Astrophysics
Zhiwei Chen, Ramotholo Sefako, Yang Yang, Zhibo Jiang, Yang Su, Shaobo Zhang, Xin Zhou
Summary: We report on the near-infrared polarimetric observations of G11.11-0.12, which reveal the presence of magnetic fields and the flow of supersonic and sub-Alfvenic gas. The magnetic fields in G11 are perpendicular to the filament and independent of its orientation relative to the Galactic plane. Gravity dominates the dynamics of G11, but magnetic fields also play a significant role. The strength of the magnetic fields increases slower than the gas density from the envelope to the spine of G11, and low-mass star formation is enhanced in filaments with high column density.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
A. Pandhi, R. K. Friesen, L. Fissel, J. E. Pineda, P. Caselli, M. C-Y Chen, J. Di Francesco, A. Ginsburg, H. Kirk, P. C. Myers, S. S. R. Offner, A. Punanova, F. Quan, E. Redaelli, E. Rosolowsky, S. Scibelli, Y. M. Seo, Y. Shirley
Summary: A study of 399 dense cores reveals that most cores have no preferred orientation between the core elongation axis, velocity gradient direction, and the ambient magnetic field orientation, supporting a triaxial and weakly magnetized origin. However, a strong evidence for a preferred anti-alignment between the core elongation axis and magnetic field is found in protostellar cores, suggesting a change in orientation from starless and prestellar populations that may result from gravitational contraction in a magnetically-regulated (but not dominant) environment. Marginal evidence for anti-alignment between the core velocity gradient and magnetic field orientation is also found in the L1228 and L1251 regions of Cepheus, suggesting a preferred orientation with respect to magnetic fields may be more prevalent in regions with locally ordered fields.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Sajay Sunny Mathew, Christoph Federrath
Summary: The study demonstrates that various factors in star cluster formation, including protostellar outflows, affect the star formation rate, mass distribution, and initial mass function. The turbulence-based model and observational IMF agree well in the high-mass and low-mass regime, but do not predict any brown dwarfs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Sajay Sunny Mathew, Christoph Federrath, Amit Seta
Summary: Turbulence is crucial for star formation, but its role in the initial mass function (IMF) is not fully understood. Magnetohydrodynamical simulations reveal that compressive turbulence driving produces a higher fraction of low-mass stars compared to solenoidal driving. The simulations capture the important features of the observed IMF form.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. S. N. Kumar, D. Arzoumanian, A. Men'shchikov, P. Palmeirim, M. Matsumura, S. Inutsuka
Summary: This study examines the detailed structure of the Mon R2 star-forming region, focusing on the role of hub-filament systems in massive star formation. The researchers find that lower density filaments converge to form higher density filaments within the hub. The structure of the hub is not a single massive clump as previously believed, but rather a network of short, high-density filaments. The analysis shows that the total mass in the region is distributed between filaments, an extended cloud, and sources. The orientation and mass per unit length of the filaments also vary with distance from the hub center.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Henry B. Lane, Michael Y. Grudic, David Guszejnov, Stella S. R. Offner, Claude-Andre Faucher-Giguere, Anna L. Rosen
Summary: Simulating isolated giant molecular clouds is important for studying star formation dynamics, but the initial conditions of turbulence are uncertain. Researchers have developed a new simulation setup that combines advantages of previous methods and found that external driving can significantly suppress star formation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jian-Wen Zhou, Shanghuo Li, Hong-Li Liu, Yaping Peng, Siju Zhang, Feng-Wei Xu, Chao Zhang, Tie Liu, Jin-Zeng Li
Summary: This study investigates the formation of hub-filament structures in the W33 complex by analyzing the velocity structures and their correlations with column density. It is suggested that the hub-filament structures are triggered by cloud-cloud collisions, and the non-thermal motions in W33-blue may originate from gravitationally driven collapse. However, the large-scale velocity gradient in W33-blue is likely influenced by cloud-cloud collisions and feedback from active star formation, rather than filament-rooted longitudinal inflow.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Rafael Zavala-Molina, Javier Ballesteros-Paredes, Adriana Gazol, Aina Palau
Summary: Recent studies propose the concept of tidal screening scenario, in which gravitationally unstable fragments near a protostar compete for gas reservoir in a star-forming clump. This contribution suggests incorporating the effect of external gravitational potential in the Jeans linear instability analysis. The research finds that an external gravitational potential can decrease the critical mass for perturbation collapse under compressive tidal forces, while increase it under disruptive tidal forces. The results provide new collapse conditions, equations for observers to determine if observed fragments can collapse, and equations to calculate fragmentation levels induced by collapse-induced turbulence.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Beuther, C. Gieser, S. Suri, H. Linz, P. Klaassen, D. Semenov, J. M. Winters, Th. Henning, J. D. Soler, J. S. Urquhart, J. Syed, S. Feng, T. Moeller, M. T. Beltran, A. Sanchez-Monge, S. N. Longmore, T. Peters, J. Ballesteros-Paredes, P. Schilke, L. Moscadelli, A. Palau, R. Cesaroni, S. Lumsden, R. Pudritz, F. Wyrowski, R. Kuiper, A. Ahmadi
Summary: The study focused on the dynamical and fragmentation properties of two young high-mass star-forming regions, revealing 29 cores mainly located along filament-like structures. The findings suggest a mass-size relation based on different temperature assumptions, with implications of thermal Jeans fragmentation and dynamical cloud collapse within the regions.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Yue Hu, Christoph Federrath, Siyao Xu, Sajay Sunny Mathew
Summary: The interaction between turbulence, magnetic fields, self-gravity, and stellar feedback is crucial for understanding star formation. This study focuses on the effects of self-gravity and outflow feedback on the turbulent velocity within molecular clouds. The results show that outflow feedback can change the scaling of velocity fluctuations and amplify turbulence. Self-gravity and protostellar outflows increase velocity fluctuations and enhance fragmentation. The study also finds that self-gravity has a more significant effect on smaller dense clumps, while outflow feedback drives a higher fraction of solenoidal modes relative to compressive modes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Andrea Bonilla-Barroso, Javier Ballesteros-Paredes, Jesus Hernandez, Luis Aguilar, Manuel Zamora-Aviles, Lee W. Hartmann, Aleksandra Kuznetsova, Vianey Camacho, Veronica Lora
Summary: Numerical simulations were used to study the formation and evolution of stellar clusters within molecular clouds. The results showed that the velocity dispersion of stars within collapsing cloud clumps remains constant regardless of their mass, while clusters formed in turbulence-dominated environments exhibit an inverse mass segregated velocity dispersion. The observations of the Orion Nebula Cluster suggested that it was formed by collapse within one free-fall time of its parental cloud. The study also addressed criticisms of models of collapsing star-forming regions and found that the observational and numerical data supported the idea of clusters forming through global, hierarchical, and chaotic collapse rather than being supported by turbulence.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Laura Ramirez-Galeano, Javier Ballesteros-Paredes, Rowan J. Smith, Vianey Camacho, Manuel Zamora-Aviles
Summary: Observational and theoretical evidence suggests that a significant portion of molecular clouds are unbound and dominated by turbulent motions. However, a more accurate calculation of the virial parameter, which takes into account not only self-gravity but also tidal stresses, reveals that a portion of the clouds are gravitationally bound but being torn apart by tides. These tidal forces primarily come from the molecular cloud complexes in which the clouds reside and possibly from massive young stellar complexes. Additionally, the results imply that interstellar turbulence may have a gravitational origin.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Nicolas Peretto, Andrew J. Rigby, Fabien Louvet, Gary A. Fuller, Alessio Traficante, Mathilde Gaudel
Summary: The formation of star clusters is crucial for the evolution of galaxies. Through a unique analysis of infrared dark clouds, it is found that most clouds are self-gravitating and the parsec-scale clumps within them are dynamically decoupled from their surrounding molecular clouds, exhibiting steeper density profiles and flat velocity dispersion profiles. This suggests that the formation of star clusters corresponds to a transition regime within the properties of self-gravitating molecular gas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
L. Bonne, N. Peretto, A. Duarte-Cabral, A. Schmiedeke, N. Schneider, S. Bontemps, A. Whitworth
Summary: By studying the newly discovered star-forming cloud G345.88-1.10, strong constraints on the evolution of massive protostellar objects can be obtained. The study found that the infrared-quiet fragments in the cloud are spatially associated with a powerful molecular outflow, and the presence of radio continuum and ionizing radiation does not seem to affect the evolution of the cavities.
ASTRONOMY & ASTROPHYSICS
(2022)
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
Enrique Vazquez-Semadeni, Alejandro Gonzalez-Samaniego, Pedro Colin
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2017)
Article
Astronomy & Astrophysics
Bastian Koertgen, Daniel Seifried, Robi Banerjee, Enrique Vazquez-Semadeni, Manuel Zamora-Aviles
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2016)
Article
Astronomy & Astrophysics
Enrique Vazquez-Semadeni, Manuel Zamora-Aviles, Roberto Galvan-Madrid, Jan Forbrich
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2018)
Review
Astronomy & Astrophysics
Jose Luis Ballester, Igor Alexeev, Manuel Collados, Turlough Downes, Robert F. Pfaff, Holly Gilbert, Maxim Khodachenko, Elena Khomenko, Ildar F. Shaikhislamov, Roberto Soler, Enrique Vazquez-Semadeni, Teimuraz Zaqarashvili
SPACE SCIENCE REVIEWS
(2018)
Article
Astronomy & Astrophysics
H. Beuther, Y. Wang, J. Soler, H. Linz, J. Henshaw, E. Vazquez-Semadeni, G. Gomez, S. Ragan, Th Henning, S. C. O. Glover, M. Y. Lee, R. Guesten
ASTRONOMY & ASTROPHYSICS
(2020)
Article
Astronomy & Astrophysics
Griselda Arroyo-Chavez, Enrique Vazquez-Semadeni
Summary: In this study, we investigated the origin of the observed scaling between the specific angular momentum and the radius of molecular clouds and their substructures, as well as the independence of the ratio of rotational to gravitational energy from the radius. By using a smoothed particle hydrodynamics simulation, we found that this relationship arises from a global tendency towards gravitational contraction mediated by angular momentum loss via turbulent viscosity, resulting in the fragmentation into low-angular momentum dense clumps and high-angular momentum diffuse envelopes.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Guido Granda-Munoz, Enrique Vazquez-Semadeni, Gilberto C. Gomez, Manuel Zamora-Aviles
Summary: The effect of numerical magnetic diffusion in magnetically supported molecular clouds is investigated. Simulations with low and intermediate resolutions collapse, while the simulation with the highest numerical resolution oscillates around an equilibrium state. By running current-sheet simulations and measuring the numerical magnetic diffusion coefficient, a criterion for the resolution of magnetic fields in MHD simulations is proposed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Raul Naranjo-Romero, Enrique Vazquez-Semadeni, Robert M. Loughnane
Summary: This study presents a numerical investigation of the gravity-driven filamentary flow and finds that a stratified simulation can best match the observed density profiles. The flow changes direction smoothly without density divergence or shock development. The accretion from the filament to the core slows down the filament growth.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jesus M. Jaquez-Dominguez, Roberto Galvan-Madrid, Jacopo Fritz, Manuel Zamora-Aviles, Peter Camps, Gustavo Bruzual, Maarten Baes, Yuxin Lin, Enrique Vazquez-Semadeni
Summary: A direct comparison between hydrodynamical simulations and observations is necessary for improving the models and testing their biases. By applying the SKIRT radiative-transfer code to simulations of a star-forming cloud, and analyzing the synthetic observations using traditional methods, we found that additional interstellar radiation is necessary in the early stages of the simulation. The morphological evolution of the cloud continues for about 8 Myr due to the expansion of H ii regions and the creation of various structures.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Feng-Wei Xu, Ke Wang, Tie Liu, Paul F. Goldsmith, Qizhou Zhang, Mika Juvela, Hong-Li Liu, Sheng-Li Qin, Guang-Xing Li, Anandmayee Tej, Guido Garay, Leonardo Bronfman, Shanghuo Li, Yue-Fang Wu, Gilberto C. Gomez, Enrique Vazquez-Semadeni, Ken'ichi Tatematsu, Zhiyuan Ren, Yong Zhang, L. Viktor Toth, Xunchuan Liu, Nannan Yue, Siju Zhang, Tapas Baug, Namitha Issac, Amelia M. Stutz, Meizhu Liu, Gary A. Fuller, Mengyao Tang, Chao Zhang, Lokesh Dewangan, Chang Won Lee, Jianwen Zhou, Jinjin Xie, Wenyu Jiao, Chao Wang, Rong Liu, Qiuyi Luo, Archana Soam, Chakali Eswaraiah
Summary: In this study, ALMA Band-3/7 observations were conducted on the massive hub-filament system SDC335 to study its fragmentation and accretion processes. The observations revealed two massive dense cores, MM1 and MM2, along with their fragmentation and temperature estimation. Gas motion analysis showed the presence of four major gas streams connected to large-scale filaments, supporting continuous accretion and core feeding. The comprehensive study of SDC335 provides valuable insights into the gas kinematics of massive infalling clumps and calls for further systematic studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Vianey Camacho, Enrique Vazquez-Semadeni, Aina Palau, Manuel Zamora-Aviles
Summary: We conducted a numerical study on the balance of gravitational, kinetic, and magnetic energies in hub-filament structures within a giant molecular cloud. The study examined the scaling relationships between the virial parameter, Larson ratio, and mass and column density of the structures. We also compared our numerical results with an observational sample of massive clumps and found similar trends. The main controlling parameter of the energy budget in the structures is gravitational energy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Ruben Guerrero-Gamboa, Enrique Vazquez-Semadeni
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Vianey Camacho, Enrique Vazquez-Semadeni, Aina Palau, Gemma Busquet, Manuel Zamora-Aviles
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Karen P. Olsen, Andrea Pallottini, Aida Wofford, Marios Chatzikos, Mitchell Revalski, Francisco Guzman, Gergoe Popping, Enrique Vazquez-Semadeni, Georgios E. Magdis, Mark L. A. Richardson, Michaela Hirschmann, William J. Gray