A Combined Photometric and Polarimetric Study of L1578 and L1607: Dust Properties and Magnetic Field Structures

Abstract We present a combined photometric and R -band polarimetric study of the Lynds dark clouds L1578 and L1607 to investigate their physical properties—such as distance, column density, and dust temperature—and to examine the morphology of their magnetic fields in the optical regime. Based on stellar radial density profiles, we estimate distances of 1043 ± 36 pc (L1578) and 938 ± 49 pc (L1607), which are compared to the distances obtained from the 3D dust-reddening maps of the sky, and the results are found to be consistent. Extinction mapping using the PNICER method yields average visual extinctions of ∼1.7 and ∼1.4 mag, with corresponding hydrogen column densities of ∼1.6 × 10 21 cm −2 and ∼1.3 × 10 21 cm −2 for L1578 and L1607, respectively. From Herschel SPIRE observations, we derive mean dust temperatures of 13.5 K (L1578) and 14.0 K (L1607), and column densities consistent with extinction-based estimates. For L1578, an elliptical fit to the central clump yields a position angle of ∼−35° and a mass of ∼35 M ⊙ ; the virial parameter is found to lie in the range 4.8–5.9, indicating a gravitationally unbound structure. Polarimetric observations show mean degrees of polarization of 3.36% ± 0.05% (L1578) and 2.84% ± 0.06% (L1607), with well-aligned polarization angles (∼149° and ∼155°, respectively). The polarization vector maps exhibit ordered magnetic fields in the cloud envelopes, closely aligned with the Galactic plane. L1578 shows no observational evidence of ongoing star formation, while further investigation is needed to assess the star-forming status of L1607.