Title：Magnetic fields in molecular clouds and star formation

Speaker：Junhao Liu (East Asian Observatory)

Location：Middle conference room, 3rd floor

Time：9:30 am July 27th (Thursday)

Tencent Meeting：576-157-8290 Password: 6360

Abstract：

The star formation process plays a fundamental role in the formation and evolution of galaxies, as well as in the life cycle of interstellar media. While significant progress has been made in understanding star formation, the role of magnetic fields in this process remains a topic of debate. Dust polarization observations, which capture linearly polarized emission from dust grains, provide valuable insights into the plane-of-sky magnetic field structure in both diffuse interstellar medium and dense molecular clouds. In this talk, I will provide a review of the magnetic field properties in molecular clouds and star formation, drawing from polarization observations analyzed using several widely-used statistical methods such as DCF, HRO, and KTH. Based on these observational studies, it has been found that molecular clouds typically exist in a trans-to-sub-Alfvénic and magnetically sub-critical state, with magnetic fields stronger than gravity and turbulence. Furthermore, as the density within molecular clouds increases, the gravitational force gradually dominates over magnetic fields, leading to the formation of magnetically trans-to-super-critical clumps and cores. Additionally, the star formation activities triggered by gravity can amplify non-thermal motions, resulting in some clumps and cores becoming super-Alfvénic, where magnetic fields are weaker than turbulence.

CV：

Dr. Junhao Liu is currently an EAO fellow at the East Asian Observatory in Hawaii. His research interests focus on studying the role of magnetic fields in star formation, especially in the early stage, with polarized dust emission observations using mm/submm single-dish telescopes and telescope arrays (e.g., JCMT, SMA, ALMA, and Planck). Junhao obtained his PhD in 2021 from Nanjing University under the supervision of Prof. Keping Qiu, and visited Center for Astrophysics (CfA) | Harvard & Smithsonian from 2018 through 2021 as an SAO predoctoral fellow under the supervision of Dr. Qizhou Zhang.