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Title: Tracing the Magnetic Field of IRDC G028.23-00.19 Using NIR Polarimetry

Abstract

The importance of the magnetic ( B ) field in the formation of infrared dark clouds (IRDCs) and massive stars is an ongoing topic of investigation. We studied the plane-of-sky B field for one IRDC, G028.23-00.19, to understand the interaction between the field and the cloud. We used near-IR background starlight polarimetry to probe the B field and performed several observational tests to assess the field importance. The polarimetric data, taken with the Mimir instrument, consisted of H -band and K -band observations, totaling 17,160 stellar measurements. We traced the plane-of-sky B -field morphology with respect to the sky-projected cloud elongation. We also found the relationship between the estimated B -field strength and gas volume density, and we computed estimates of the normalized mass-to-magnetic flux ratio. The B -field orientation with respect to the cloud did not show a preferred alignment, but it did exhibit a large-scale pattern. The plane-of-sky B -field strengths ranged from 10 to 165 μ G, and the B -field strength dependence on density followed a power law with an index consistent with 2/3. The mass-to-magnetic flux ratio also increased as a function of density. The relative orientations and relationship between the B field and densitymore » imply that the B field was not dynamically important in the formation of the IRDC. The increase in mass-to-flux ratio as a function of density, though, indicates a dynamically important B field. Therefore, it is unclear whether the B field influenced the formation of G28.23. However, it is likely that the presence of the IRDC changed the local B -field morphology.« less

Authors:
; ;  [1];  [2]
  1. Institute for Astrophysical Research, 725 Commonwealth Ave, Boston University, Boston, MA 02215 (United States)
  2. Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago (Chile)
Publication Date:
OSTI Identifier:
22663776
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 836; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DENSITY; DUSTS; ELONGATION; INTERACTIONS; MAGNETIC FIELDS; MAGNETIC FLUX; MASS; NEAR INFRARED RADIATION; POLARIMETRY; SKY; STARS

Citation Formats

Hoq, Sadia, Clemens, D. P., Cashman, Lauren R., and Guzmán, Andrés E., E-mail: shoq@bu.edu, E-mail: clemens@bu.edu, E-mail: lcashman@bu.edu, E-mail: aguzman@das.uchile.cl. Tracing the Magnetic Field of IRDC G028.23-00.19 Using NIR Polarimetry. United States: N. p., 2017. Web. doi:10.3847/1538-4357/836/2/199.
Hoq, Sadia, Clemens, D. P., Cashman, Lauren R., & Guzmán, Andrés E., E-mail: shoq@bu.edu, E-mail: clemens@bu.edu, E-mail: lcashman@bu.edu, E-mail: aguzman@das.uchile.cl. Tracing the Magnetic Field of IRDC G028.23-00.19 Using NIR Polarimetry. United States. doi:10.3847/1538-4357/836/2/199.
Hoq, Sadia, Clemens, D. P., Cashman, Lauren R., and Guzmán, Andrés E., E-mail: shoq@bu.edu, E-mail: clemens@bu.edu, E-mail: lcashman@bu.edu, E-mail: aguzman@das.uchile.cl. Mon . "Tracing the Magnetic Field of IRDC G028.23-00.19 Using NIR Polarimetry". United States. doi:10.3847/1538-4357/836/2/199.
@article{osti_22663776,
title = {Tracing the Magnetic Field of IRDC G028.23-00.19 Using NIR Polarimetry},
author = {Hoq, Sadia and Clemens, D. P. and Cashman, Lauren R. and Guzmán, Andrés E., E-mail: shoq@bu.edu, E-mail: clemens@bu.edu, E-mail: lcashman@bu.edu, E-mail: aguzman@das.uchile.cl},
abstractNote = {The importance of the magnetic ( B ) field in the formation of infrared dark clouds (IRDCs) and massive stars is an ongoing topic of investigation. We studied the plane-of-sky B field for one IRDC, G028.23-00.19, to understand the interaction between the field and the cloud. We used near-IR background starlight polarimetry to probe the B field and performed several observational tests to assess the field importance. The polarimetric data, taken with the Mimir instrument, consisted of H -band and K -band observations, totaling 17,160 stellar measurements. We traced the plane-of-sky B -field morphology with respect to the sky-projected cloud elongation. We also found the relationship between the estimated B -field strength and gas volume density, and we computed estimates of the normalized mass-to-magnetic flux ratio. The B -field orientation with respect to the cloud did not show a preferred alignment, but it did exhibit a large-scale pattern. The plane-of-sky B -field strengths ranged from 10 to 165 μ G, and the B -field strength dependence on density followed a power law with an index consistent with 2/3. The mass-to-magnetic flux ratio also increased as a function of density. The relative orientations and relationship between the B field and density imply that the B field was not dynamically important in the formation of the IRDC. The increase in mass-to-flux ratio as a function of density, though, indicates a dynamically important B field. Therefore, it is unclear whether the B field influenced the formation of G28.23. However, it is likely that the presence of the IRDC changed the local B -field morphology.},
doi = {10.3847/1538-4357/836/2/199},
journal = {Astrophysical Journal},
number = 2,
volume = 836,
place = {United States},
year = {Mon Feb 20 00:00:00 EST 2017},
month = {Mon Feb 20 00:00:00 EST 2017}
}