Abstract Details

Name: Eswaraiah Chakali
Affiliation: National Astronomical Observatories of China (NAOC)
Conference ID: ASI2020_393
Title : Importance of magnetic fields in star formation – a multi-wavelength perspective
Authors and Co-Authors : Eswariaha Chakali, Di Li, Shih-Ping Lai, Anil K. Pandey, Jia-Wei Wang, Manash R. Samal, Yuehui Ma, Jessy Jose, D. K. Ojha, and collaborators
Abstract Type : Oral
Abstract Category : Stars, ISM and Galaxy
Abstract : Magnetic fields (B-fields) are crucial to the formation and evolution of molecular clouds and stars, yet B-fields remain poorly constrained in comparison to the other key agents such as gravity and turbulence. In this presentation, I will summarize our results based on dust extinction (at optical/near-infrared) and emission (at sub-mm) polarization observations towards the star-forming regions. These observations are used to probe the geometry of B-fields at scales and densities ranging from the low-density outer parts of molecular clouds (10’s of pc to several pc) to the highly obscured dense cores (< 0.1 pc). The morphological comparisons among the B-fields, cloud, filament, core, and outflows, etc, provide a crucial information as to test whether B-fields are dynamically important. We have performed the Angular Dispersion Function (ADF) analyses to derive the ratio of large scale order to turbulent B-field strengths. Davis-Chandersekhar-Fermi relation (and its modified relations) are used to quantify the B-field strength. Quantitative comparisons, among turbulence to magnetic pressure ratio, thermal to magnetic pressure ratio, mass-to-flux ratio criticality, etc, have been made to evaluate the relative importance of B-fields to turbulence, gravity, thermal pressure. We show that polarization observations along with the distance information (from GAIA DR2) as well as molecular lines data (from PMO/FCRAO) are useful to extract the cloud's polarization components. In the low-density outer parts, B-fields find to be important in regulating cloud's accumulation and evolution, while at the denser parts the gravity and cloud kinematics come into active play. B-fields are shown to be compressed and their strength has been enhanced in the vicinity of HII regions. Stronger B-fields are important to the formation and evolution of clumps and feedback processes, especially, in the later stages.