The Magnetic Field of L1544: I. Near-Infrared Polarimetry and the Non-Uniform Envelope

Abstract

The magnetic field (B-field) of the starless dark cloud L1544 has been studied using near-infrared (NIR) background starlight polarimetry (BSP) and archival data in order to characterize the properties of the plane-of-sky B-field. NIR linear polarization measurements of over 1,700 stars were obtained in the H-band and 201 of these were also measured in the K-band. The NIR BSP properties are correlated with reddening, as traced using the RJCE (H-M) method, and with thermal dust emission from the L1544 cloud and envelope seen in Herschel maps. The NIR polarization position angles change at the location of the cloud and exhibit their lowest dispersion of position angles there, offering strong evidence that NIR polarization traces the plane-of-sky B-field of L1544. In this paper, the uniformity of the plane-of-sky B-field in the envelope region of L1544 is quantitatively assessed. This allowed evaluating the approach of assuming uniform field geometry when measuring relative mass-to-flux ratios in the cloud envelope and core based on averaging of the envelope radio Zeeman observations, as in Crutcher et al. (2009). In L1544, the NIR BSP shows the envelope B-field to be significantly non-uniform and likely not suitable for averaging Zeeman properties without treating intrinsic variations. Deeper analyses of the NIR BSP and related data sets, including estimates of the B-field strength and testing how it varies with position and gas density, are the subjects of later papers in this series.

arXiv comment16 pages, 9 figures; accepted for publication in The Astrophysical Journal

References in corpus (43)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• SCUBA: A common-user submillimetre camera operating on the James Clerk Maxwell Telescope
• Dense Cores in Dark Clouds. XIV. N2H+(1-0) maps of dense cloud cores
• Systematic Molecular Differentiation in Starless Cores
• Probing the evolutionary status of starless cores through N2H+ and N2D+ observations
• Molecular ions in L1544. II. The ionization degree
• A Super-Alfvenic Model of Dark Clouds
• The Third US Naval Observatory CCD Astrograph Catalog (UCAC3)
• Helical Fields and Filamentary Molecular Clouds
• Magnetic processes in a collapsing dense core. I Accretion and Ejection
• Tracing the Mass during Low-Mass Star Formation. I. Submillimeter Continuum Observations
• SCUBA Polarization Measurements of the Magnetic Field Strengths in the L183, L1544, and L43 Prestellar Cores
• Magnetic Fields in Dark Cloud Cores: Arecibo OH Zeeman Observations
• Magnetic Fields in High-Mass Infrared Dark Clouds
• Magnetic Fields and Massive Star Formation
• Lifting the Dusty Veil With Near- and Mid-Infrared Photometry: I. Description and Applications of the Rayleigh-Jeans Color Excess Method
• First Observations of the Magnetic Field Geometry in Pre-stellar Cores
• Dynamics and Depletion in Thermally Supercritical Starless Cores
• Molecular ions in L1544. I. Kinematics
• The Efficiency of Grain Alignment in Dense Interstellar Clouds: A Reassessment of Constraints from Near Infrared Polarization
• Observational Constraints on the Ages of Molecular Clouds and the Star-Formation Timescale: Ambipolar-Diffusion--Controlled or Turbulence-Induced Star Formation?
• The Different Structures of the Two Classes of Starless Cores
• Testing Magnetic Star Formation Theory
• Consistency of Ambipolar Diffusion Models with Infall in the L1544 Protostellar Core
• Deuterated methanol in the pre-stellar core L1544
• A High Resolution Study of the Slowly Contracting, Starless Core L1544
• The dynamics of collapsing cores and star formation
• Chemistry and Dynamics in Pre-Protostellar Cores
• VLBA determination of the distance to nearby star-forming regions V. Dynamical mass, distance and radio structure of V773 Tau A
• The Distribution of Ortho-H_2D+(1_1,0 - 1_1,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores
• Magnetized Interstellar Molecular Clouds. I. Comparison Between Simulations and Zeeman Observations
• Grain Alignment in Starless Cores
• A Submillimetre Imaging Polarimeter at the James Clerk Maxwell Telescope
• The Polarizing Power of the Interstellar Medium in Taurus
• Chemistry and Radiative Transfer of Water in Cold, Dense Clouds
• Line profiles of molecular ions toward the pre-stellar core LDN 1544
• A Coupled Dynamical and Chemical Model of Starless Cores of Magnetized Molecular Clouds: I. Formulation and Initial Results
• Water vapor toward starless cores: the Herschel view
• A high resolution comparative study of the slowly contracting, starless cores, L694-2 and L1544
• Self-Consistent Analysis of OH-Zeeman Observations: Too Much Noise about Noise
• Interstellar Polarization in the Taurus Dark Clouds, Wavelength Dependent Position Angles and Cloud Structure Near TMC-1
• Constraining the structure of the non-spherical preprotostellar core L1544
• Fragmentation of Magnetically Subcritical Clouds into Multiple Supercritical Cores and the Formation of Small Stellar Groups

Cited by in corpus (10)

• Grain alignment and disruption by radiative torques in dense molecular clouds and implication for polarization holes
• An Early Transition to Magnetic Supercriticality in Star Formation
• Seeds of Life in Space (SOLIS). III. Zooming into the methanol peak of the pre-stellar core L1544
• Multi-wavelength Stellar Polarimetry of the Filamentary Cloud IC5146: I. Dust Properties
• Magnetic Field Structure in Spheroidal Star-Forming Clouds
• Three-dimensional magnetic fields of molecular clouds
• Deflections of ultra-high energy cosmic rays by the Milky Way magnetic field: how well can they be corrected?
• Magnetic Field Uniformity Across the GF 9-2 YSO, L1082C Dense Core, and GF 9 Filamentary Dark Cloud
• The embedded ring-like feature and star formation activities in G35.673-00.847
• Near-Infrared Polarization from Unresolved Disks Around Brown Dwarfs and Young Stellar Objects