H_I-H₂ transition: Exploring the role of the magnetic field

Atomic gas in the diffuse interstellar medium (ISM) is organized filamentary structures. These structures usually host cold and dense molecular clumps. The Galactic magnetic field considered to play an important role formation of these Our goal explore HI - H$_{2}$ transition process. We targeted a cloud where transitions from atomic molecular. This located at edges expanding structure, known as North Celestial Pole Loop (NCPL). probed properties with optical polarization observations. performed multi-wavelength spectroscopic observations different species order probe phase cloud. identified two distinct sub-regions within One regions hosts purely gas, while other dominated by although most it CO-dark. estimated plane-of-the-sky strength between remains constant uncertainties lies range 20 ~ 30$~\mu$G. total does not scale density which implies that compressed along lines. also found turbulence sub-Alfv\'enic. velocity gradients are general perpendicular mean orientation, except for region close CO clump they tend become parallel. latter likely related undergoing gravitational infall. morphology target parallel column structure region, tends region. If this verified more cases has consequences ISM modeling data.