Article
Astronomy & Astrophysics
Charles Yin, Felix D. Priestley, James Wurster
Summary: Determining the importance of magnetic fields in star-forming environments is hindered by the challenge of accurately measuring both field strength and gas properties in molecular clouds. By simulating pre-stellar cores and varying the initial mass-to-flux ratio, significant changes were observed in the intensity and shape of several key molecular lines, leading to the identification of promising diagnostics of the initial mass-to-flux ratio. Despite being magnetically supercritical at present, the criteria suggest that L1498 formed from subcritical initial conditions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Cynthia R. Saad, Volker Bromm, Mounib El Eid
Summary: The study shows that magnetic fields play an important role in the formation of the first stars, delaying the collapse of gas and affecting the fragmentation and final mass of the stars. Further understanding of the formation and mass distribution of Population III stars requires considering the impact of magnetic fields.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Renato Mazzei, Zhi-Yun Li, Che-Yu Chen, Laura Fissel, Mike Chen, James Park
Summary: We compared the structure of synthetic dust polarization with synthetic molecular line emission using a three-dimensional, turbulent collapsing-cloud magnetohydrodynamics simulation. We found that the transition to perpendicular alignment occurs at densities above 4 x 10(3) cm(-3) in our trans-Alfvenic simulation, but not for (CO)-C-12. The magnetic field becomes significantly more tangled in our super-Alfvenic simulation, and all observed tracers tend towards no preference for alignment.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Siddharth Kumar, Archana Soam, Nirupam Roy
Summary: This study presents the magnetic field geometry of three cometary globules, LDN 323, LDN 328, and LDN 331, using R-band polarization measurements of background stars. The observations were combined with a Planck sky survey to study the large-scale morphology of the magnetic fields in the region. Analysis of the degree of polarization and polarization position angle with distances of stars showed that the field geometry mostly follows the cometary shape of the cloud, with some randomness at certain locations. A modified version of the histogram of relative orientation (HRO) analysis was employed to study the correlation between cloud morphology and magnetic field orientations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
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
Colin H. Sullivan, L. M. Fissel, P. K. King, C-Y Chen, Z-Y Li, J. D. Soler
Summary: This study aims to characterize the 3D magnetic field properties of nearby molecular clouds by statistically analyzing polarized dust emission maps. By comparing various analysis techniques, a more comprehensive view of the cloud's magnetic field properties is proposed. The results indicate inverse correlations between polarization fraction and dispersion in polarization angles, as well as hydrogen column density, but a clear trend between S and N-H could not be established.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Zhiwei Chen, Ramotholo Sefako, Yang Yang, Zhibo Jiang, Shuling Yu, Jia Yin
Summary: We report the near-infrared polarimetric observations of RCW 120, which reveal the magnetic field structure for the first time. The global magnetic field is aligned along a direction of 20 degrees, parallel to the Galactic plane, with a plane-of-sky strength of 100 +/- 26 mu G. The magnetic field around the eastern shell appears to have been compressed by the neighboring H ii region, causing the observed elongation of RCW 120. The presence of a strong magnetic field reduces the efficiency of triggered star formation compared to hydrodynamic estimates, but it can still occur in the direction along the magnetic field.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
J. D. Livingston, N. M. McClure-Griffiths, S. A. Mao, Y. K. Ma, B. M. Gaensler, G. Heald, A. Seta
Summary: Studying the magnetic fields of low-mass interacting galaxies reveals their evolution over cosmic time. The Faraday rotation measurements of the Small Magellanic Cloud show a coherent line-of-sight magnetic field strength consistent with previous findings. The similarities in direction and strength of the magnetic fields between the Small Magellanic Cloud and Magellanic Bridge suggest a connection between the two as part of the hypothesized ‘pan-Magellanic’ magnetic field.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
S. Ekta, G. Maheswar, D. Sami
Summary: This study estimated the motions of four clouds in the Cepheus Flare region and studied their relationship with the magnetic field and clump orientations. The results showed that the motions of the clouds were offset by approximately 30 degrees with respect to the magnetic fields, except for one cloud. The clump orientations were randomly distributed with respect to the magnetic fields in most clouds. Additionally, there was a correlation between the motion of the clouds and the orientations of the clumps.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Kate Pattle, Shih-Ping Lai, Sarah Sadavoy, Simon Coude, Sebastian Wolf, Ray Furuya, Woojin Kwon, Chang Won Lee, Niko Zielinski
Summary: In this study, the large Bok globule CB 54 was observed using the POL-2 polarimeter on the JCMT. The results show that the magnetic field in the periphery of the globule deviates significantly from the mean-field direction in the center, which may be influenced by the weak outflow from the Class 0 sources. The analysis suggests that the magnetic field strength in the periphery is less than 27 mu G. Furthermore, comparison with other measurements indicates that the field in the center of the globule is consistent and aligned with the density structure. Therefore, even a weak outflow can reshape the magnetic fields in star-forming regions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(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
C. Sobey, S. Johnston, S. Dai, M. Kerr, R. N. Manchester, L. S. Oswald, A. Parthasarathy, R. M. Shannon, P. Weltevrede
Summary: In this study, high signal-to-noise ratio, full polarization pulse profiles for 40 bright, 'slowly' rotating pulsars were presented using the new ultrawideband low-frequency receiver on the Parkes radio telescope. The results revealed trends in the pulse profiles and provided valuable insights into pulsar emission and the intervening interstellar medium. The calibrated data products are publicly available for further research and analysis.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
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
Ronan Hix, Chong-Chong He, Massimo Ricotti
Summary: In this study, we performed numerical simulations of turbulent molecular clouds with varying initial magnetic field strength. We found that increasing the strength of the magnetic field leads to a transition from unimodal to bimodal star formation. The strongly magnetized clouds exhibit a two-phase star formation process, with the second phase producing only low-mass stars. This bimodality may have implications for understanding the origin of multiple stellar populations in massive globular clusters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
D. Arzoumanian, R. S. Furuya, T. Hasegawa, M. Tahani, S. Sadavoy, C. L. H. Hull, D. Johnstone, P. M. Koch, S. Inutsuka, Y. Doi, T. Hoang, T. Onaka, K. Iwasaki, Y. Shimajiri, T. Inoue, N. Peretto, P. Andre, P. Bastien, D. Berry, H. -R. V. Chen, J. Di Francesco, C. Eswaraiah, L. Fanciullo, L. M. Fissel, J. Hwang, J. H. Kang, G. Kim, K. -T. Kim, F. Kirchschlager, W. Kwon, C. W. Lee, H. -L. Liu, A. -R. Lyo, K. Pattle, A. Soam, X. Tang, A. Whitworth, T. -C. Ching, S. Coude, J. -W. Wang, D. Ward-Thompson, S. -P. Lai, K. Qiu, T. L. Bourke, D. -Y. Byun, M. Chen, Z. Chen, W. P. Chen, J. Cho, Y. Choi, M. Choi, A. Chrysostomou, E. J. Chung, S. Dai, P. N. Diep, H. -Y. Duan, Y. Duan, D. Eden, J. Fiege, E. Franzmann, P. Friberg, G. Fuller, T. Gledhill, S. Graves, J. Greaves, M. Griffin, Q. Gu, I. Han, J. Hatchell, S. Hayashi, M. Houde, I. -G. Jeong, M. Kang, S. -j. Kang, A. Kataoka, K. Kawabata, F. Kemper, M. -R. Kim, K. H. Kim, J. Kim, S. Kim, J. Kirk, M. I. N. Kobayashi, V. Konyves, T. Kusune, J. Kwon, K. Lacaille, C. -Y. Law, C. -F. Lee, Y. -H. Lee, S. -S. Lee, H. Lee, J. -E. Lee, H. -b. Li, D. Li, D. L. Li, J. Liu, T. Liu, S. -Y. Liu, X. Lu, S. Mairs, M. Matsumura, B. Matthews, G. Moriarty-Schieven, T. Nagata, F. Nakamura, H. Nakanishi, N. B. Ngoc, N. Ohashi, G. Park, H. Parsons, T. -S. Pyo, L. Qian, R. Rao, J. Rawlings, M. Rawlings, B. Retter, J. Richer, A. Rigby, H. Saito, G. Savini, A. Scaife, M. Seta, H. Shinnaga, M. Tamura, Y. -W. Tang, K. Tomisaka, L. N. Tram, Y. Tsukamoto, S. Viti, H. Wang, J. Xie, H. -W. Yen, H. Yoo, J. Yuan, H. -S. Yun, T. Zenko, G. Zhang, C. -P. Zhang, Y. Zhang, J. Zhou, L. Zhu, I. de Looze, C. D. Dowell, S. Eyres, S. Falle, R. Friesen, J. -F. Robitaille, S. van Loo
Summary: This study aims to understand the role of magnetic fields in the dynamical evolution of the NGC 6334 filament network with cluster-forming hubs. Observations show a complex B-field structure across the region, while exhibiting coherent variations along the filament crests. Variations in polarization properties along sub-filaments may trace the evolution of physical properties during interactions with ridges and hubs. Feedback from young high-mass stars impacts the local B-field structure and polarization properties, shedding light on the interplay between star formation activity and interstellar B-fields.
ASTRONOMY & ASTROPHYSICS
(2021)