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Title: HIGH-RESOLUTION 8 mm AND 1 cm POLARIZATION OF IRAS 4A FROM THE VLA NASCENT DISK AND MULTIPLICITY (VANDAM) SURVEY

Magnetic fields can regulate disk formation, accretion, and jet launching. Until recently, it has been difficult to obtain high-resolution observations of the magnetic fields of the youngest protostars in the critical region near the protostar. The VANDAM survey is observing all known protostars in the Perseus Molecular Cloud. Here we present the polarization data of IRAS 4A. We find that with ∼0.″2 (50 AU) resolution at λ = 8.1 and 10.3 mm, the inferred magnetic field is consistent with a circular morphology, in marked contrast with the hourglass morphology seen on larger scales. This morphology is consistent with frozen-in field lines that were dragged in by rotating material entering the infall region. The field morphology is reminiscent of rotating circumstellar material near the protostar. This is the first polarization detection of a protostar at these wavelengths. We conclude from our observations that the dust emission is optically thin with β ∼ 1.3, suggesting that millimeter-/centimeter-sized grains have grown and survived in the short lifetime of the protostar.
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ; ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)
  2. Leiden Observatory, Leiden University, P.O. Box 9513, 2000-RA Leiden (Netherlands)
  3. Department of Astronomy, University of Virginia, Charlottesville, VA 22903 (United States)
  4. Astronomical Observatory Institute, Faculty of Physics, A. Mickiewicz University, Słoneczna 36, PL-60-268 Poznań (Poland)
  5. National Radio Astronomy Observatory, Socorro, NM 87801 (United States)
  6. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
  7. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
  8. Center for Astrophysics and Space Sciences, University of California, San Diego, CA 92093 (United States)
  9. Max-Planck-Institut für Astronomie, D-69117 Heidelberg (Germany)
Publication Date:
OSTI Identifier:
22518669
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 814; 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; EMISSION; LIFETIME; MAGNETIC FIELDS; MORPHOLOGY; MULTIPLICITY; POLARIZATION; PROTOSTARS; RESOLUTION; STARS