High-resolution 8 mm and 1 cm polarization of IRAS 4A from the VLA Nascent Disk and Multiplicity (VANDAM) survey

Erin G. Cox, Robert J. Harris, Leslie W. Looney, Dominique M. Segura-Cox, John Tobin, Zhi Yun Li, Łukasz Tychoniec, Claire J. Chandler, Michael M. Dunham, Kaitlin Kratter, Carl Melis, Laura M. Perez, Sarah I. Sadavoy

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

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.

Original languageEnglish (US)
Article numberL28
JournalAstrophysical Journal Letters
Volume814
Issue number2
DOIs
StatePublished - Dec 1 2015

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Keywords

  • circumstellar matter
  • stars: formation
  • stars: magnetic field

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Cox, E. G., Harris, R. J., Looney, L. W., Segura-Cox, D. M., Tobin, J., Li, Z. Y., Tychoniec, Ł., Chandler, C. J., Dunham, M. M., Kratter, K., Melis, C., Perez, L. M., & Sadavoy, S. I. (2015). High-resolution 8 mm and 1 cm polarization of IRAS 4A from the VLA Nascent Disk and Multiplicity (VANDAM) survey. Astrophysical Journal Letters, 814(2), [L28]. https://doi.org/10.1088/2041-8205/814/2/L28