New Results on the Submillimeter Polarization Spectrum of the Orion Molecular Cloud

We have used the SHARP polarimeter at the Caltech Submillimeter Observatory to map the polarization at wavelengths of 350 and 450 μm in a ~2' × 3' region of the Orion Molecular Cloud. The map covers the brightest region of the OMC-1 ridge including the Kleinmann-Low (KL) nebula and the submillimeter source Orion-south. The ratio of 450 to 350 μm polarization is ~1.3 ± 0.3 in the outer parts of the cloud and drops by more than a factor of 2 toward KL. The outer cloud ratio is consistent with measurements in other clouds at similar wavelengths and confirms previous measurements placing the minimum of the polarization ratio in dusty molecular clouds at λ ~ 350 μm .

[1]  Jessie L. Dotson,et al.  Hale: a multi-wavelength far-infrared polarimeter for SOFIA , 2003, SPIE Astronomical Telescopes + Instrumentation.

[2]  Jessie L. Dotson,et al.  Far-Infrared Polarimetry of Galactic Clouds from the Kuiper Airborne Observatory , 2000 .

[3]  F. Boulanger,et al.  Sky Polarisation at Far-Infrared to Radio Wavelengths: The Galactic Screen before the Cosmic Microwave Background , 2007 .

[4]  A. Lazarian.  Magnetic fields via polarimetry: progress on grain alignment theory , 2002 .

[5]  Jessie L. Dotson,et al.  The Far-Infrared Polarization Spectrum: First Results and Analysis , 1999 .

[6]  J. Hough,et al.  The magnetic field structure in W51A , 2002, astro-ph/0201499.

[7]  D. A. Schleuning,et al.  Far-infrared and Submillimeter Polarization of OMC-1: Evidence for Magnetically Regulated Star Formation , 1997 .

[8]  Inverse temperature dependence of the dust submillimeter spectral index , 2003, astro-ph/0310091.

[9]  S. Whitcomb,et al.  A high resolution submillimeter map of OMC-1 , 1982 .

[10]  J. Vaillancourt,et al.  Design and initial performance of SHARP, a polarimeter for the SHARC-II camera at the Caltech Submillimeter Observatory. , 2007, Applied optics.

[11]  John E. Vaillancourt,et al.  Placing Confidence Limits on Polarization Measurements , 2006, astro-ph/0603110.

[12]  John E. Vaillancourt,et al.  Analysis of the Far-Infrared/Submillimeter Polarization Spectrum Based on Temperature Maps of Orion , 2002 .

[13]  E. Serabyn,et al.  350 Micron Continuum Imaging of the Orion A Molecular Cloud with the Submillimeter High Angular Resolution Camera , 1998 .

[14]  C. D. Wilson,et al.  MAGNETIC FIELDS IN STAR-FORMING MOLECULAR CLOUDS. II. THE DEPOLARIZATION EFFECT IN THE OMC-3 FILAMENT OF ORION A , 2001 .

[15]  Stephen R. Platt,et al.  100-micron array polarimetry from the Kuiper Airborne Observatory - Instrumentation, techniques, and first results , 1991 .

[16]  J. Bally,et al.  JCMT/SCUBA Submillimeter Wavelength Imaging of the Integral-shaped Filament in Orion , 1998 .

[17]  J. Hough,et al.  The Efficiency of Grain Alignment in Dense Interstellar Clouds: a Reassessment of Constraints from Near-Infrared Polarization , 2007, 0711.2536.

[18]  Jessie L. Dotson,et al.  A Primer on Far‐Infrared Polarimetry , 2000 .

[19]  California Institute of Technology,et al.  Astronomical image processing with array detectors , 2007 .

[20]  Mark Dragovan,et al.  The Shapes and Alignment Properties of Interstellar Dust Grains , 1995 .

[21]  David T. Chuss,et al.  Far-infrared polarimetry from the Stratospheric Observatory for Infrared Astronomy , 2007, SPIE Optical Engineering + Applications.

[22]  A. Lazarian,et al.  Tracing Magnetic Fields with Aligned Grains , 2007, 0707.0858.

[23]  David T. Chuss,et al.  A polarimetry module for CSO/SHARC-II , 2004, SPIE Astronomical Telescopes + Instrumentation.

[24]  B. Draine,et al.  Astrophysics of Dust , 2004 .

[25]  Peter G. Martin,et al.  Interstellar Extinction and Polarization in the Infrared , 1990 .

[26]  J. Bernard,et al.  Submillimeter Mapping and Analysis of Cold Dust Condensations in the Orion M42 Star-forming Complex , 2001, astro-ph/0102407.

[27]  Jessie L. Dotson,et al.  Tracing the Magnetic Field in Orion A , 2004 .

[28]  Geoffrey C. Clayton,et al.  Ultraviolet Interstellar Linear Polarization. V. Analysis of the Final Data Set , 1999 .

[29]  C. Curry,et al.  SFChem 2002: Chemistry as a Diagnostic of Star Formation , 2003 .

[30]  S. Potter,et al.  Observational Constraints on Interstellar Grain Alignment , 2007, 0705.1306.

[31]  Marija Strojnik-Scholl,et al.  Infrared Spaceborne Remote Sensing and Instrumentation XV , 2007 .

[32]  A. Chrysostomou,et al.  Magnetic fields in massive star-forming regions , 2007, 0709.0256.