The JCMT BISTRO Survey: The Magnetic Field in the Starless Core ρ Ophiuchus C

We report 850 μm dust polarization observations of a low-mass (∼12 M⊙) starless core in the ρ Ophiuchus cloud, Ophiuchus C, made with the POL-2 instrument on the James Clerk Maxwell Telescope (JCMT) as part of the JCMT B-fields In STar-forming Region Observations survey. We detect an ordered magnetic field projected on the plane of the sky in the starless core. The magnetic field across the ∼0.1 pc core shows a predominant northeast–southwest orientation centering between ∼40° and ∼100°, indicating that the field in the core is well aligned with the magnetic field in lower-density regions of the cloud probed by near-infrared observations and also the cloud-scale magnetic field traced by Planck observations. The polarization percentage (P) decreases with increasing total intensity (I), with a power-law index of −1.03 ± 0.05. We estimate the plane-of-sky field strength (Bpos) using modified Davis–Chandrasekhar–Fermi methods based on structure function (SF), autocorrelation function (ACF), and unsharp masking (UM) analyses. We find that the estimates from the SF, ACF, and UM methods yield strengths of 103 ± 46 μG, 136 ± 69 μG, and 213 ± 115 μG, respectively. Our calculations suggest that the Ophiuchus C core is near magnetically critical or slightly magnetically supercritical (i.e., unstable to collapse). The total magnetic energy calculated from the SF method is comparable to the turbulent energy in Ophiuchus C, while the ACF method and the UM method only set upper limits for the total magnetic energy because of large uncertainties.

Lei Zhu | E. Pascale | A. Scaife | P. Koch | A. Whitworth | N. Peretto | G. Fuller | H. Chen | T. Onaka | M. Tamura | Sang-Sung Lee | D. Byun | D. Johnstone | P. Bastien | Jongsoo Kim | G. Savini | J. Francesco | B. Matthews | Di Li | P. Friberg | M. Seta | J. Kwon | T. Nagata | Tsuyoshi Inoue | W. Chen | K. Kawabata | S. Eyres | S. Falle | M. Griffin | W. Holland | J. Greaves | G. Moriarty-Schieven | T. Hasegawa | D. Ward-Thompson | J. Hatchell | A. Chrysostomou | J. Fiege | R. Friesen | S. Graves | M. Houde | J. Kirk | J. Richer | P. Andr'e | K. Lacaille | C. Dowell | A. Kataoka | R. Rao | M. Rawlings | H. Parsons | Jia‐Wei Wang | L. Qian | K. Qiu | T. Ching | Jinghua Yuan | A. Rigby | Jianjun Zhou | Da-lei Li | Miju Kang | Il-Gyo Jeong | H. Nakanishi | Jeong-Eun Lee | Kee-Tae Kim | Hongchi Wang | Zhiwei Chen | Tie Liu | Ji-hyun Kang | S. Inutsuka | F. Kemper | Minho Choi | Sung-ju Kang | Jungyeon Cho | H. Yoo | D. Berry | T. Pyo | F. Nakamura | S. Loo | D. Arzoumanian | Guoyin Zhang | Junhao Liu | Y. Doi | J. Robitaille | Chuan-Peng Zhang | Hua-b. Li | Sheng-Yuan Liu | S. Lai | A. Soam | C. Lee | Ya-Wen Tang | Gwanjeong Kim | S. Mairs | Shinyoung Kim | K. Pattle | W. Kwon | E. Chung | A. Pon | S. Hayashi | M. Matsumura | Yapeng Zhang | S. Sadavoy | K. Tomisaka | Y. Tsukamoto | Hsi-Wei Yen | N. Ohashi | K. Iwasaki | Yusuke Aso | Chin-Fei Lee | H. Shinnaga | L. Fanciullo | M. C. Chen | E. Drabek-Maunder | T. Gledhill | Mi-Ryang Kim | R. Furuya | S. Coud'e | C. Eswaraiah | K. Kim | A. Lyo | B. Retter | I. Han | Hyeseung Lee | Thiem C. Hoang | T. Zenko | Masato I. N. Kobayashi | E. Franzmann | Hong-Li Liu | Q. Gu | Yoshihiro Kanamori | H. Saito | J. Hwang | T. Kusune | Josh Parker | T. Inoue | S. Lai | Hongli Liu | Chuan-peng Zhang | W. Chen | Ya-wen Tang | Takayoshi Kusune

[1]  J. Aumont,et al.  Planck2018 results , 2018, Astronomy & Astrophysics.

[2]  Tetsuo Hasegawa,et al.  First Observations of the Magnetic Field inside the Pillars of Creation: Results from the BISTRO Survey , 2018, The Astrophysical Journal.

[3]  Lei Zhu,et al.  Magnetic Fields toward Ophiuchus-B Derived from SCUBA-2 Polarization Measurements , 2018, The Astrophysical Journal.

[4]  Lei Zhu,et al.  A First Look at BISTRO Observations of the ρ Oph-A core , 2018, 1804.09313.

[5]  P. Koch,et al.  The JCMT BISTRO Survey: The Magnetic Field Strength in the Orion A Filament , 2017, 1707.05269.

[6]  M. Tamura,et al.  Distortion of Magnetic Fields in a Starless Core: Near-infrared Polarimetry of FeSt 1–457 , 2017, 1707.00720.

[7]  A. Goodman,et al.  Unveiling the Role of the Magnetic Field at the Smallest Scales of Star Formation , 2017, 1706.03806.

[8]  Saeko S. Hayashi,et al.  First Results from BISTRO: A SCUBA-2 Polarimeter Survey of the Gould Belt , 2017, 1704.08552.

[9]  L. Hartmann,et al.  THE GOULD’S BELT DISTANCES SURVEY (GOBELINS). I. TRIGONOMETRIC PARALLAX DISTANCES AND DEPTH OF THE OPHIUCHUS COMPLEX , 2016, 1611.06466.

[10]  Giorgio Savini,et al.  POL-2: a polarimeter for the James-Clerk-Maxwell telescope , 2016, Astronomical Telescopes + Instrumentation.

[11]  P. Hennebelle,et al.  Magnetic field morphology in nearby molecular clouds as revealed by starlight and submillimetre polarization , 2016, 1605.09371.

[12]  Jungyeon Cho,et al.  A TECHNIQUE FOR CONSTRAINING THE DRIVING SCALE OF TURBULENCE AND A MODIFIED CHANDRASEKHAR–FERMI METHOD , 2016, 1603.08537.

[13]  G. W. Pratt,et al.  Planck intermediate results. XXXV. Probing the role of the magnetic field in the formation of structure in molecular clouds , 2015, 1502.04123.

[14]  J. Hough,et al.  WIDE-FIELD INFRARED POLARIMETRY OF THE ρ OPHIUCHI CLOUD CORE , 2015 .

[15]  E. Rosolowsky,et al.  The JCMT Gould Belt Survey: first results from the SCUBA-2 observations of the Ophiuchus molecular cloud and a virial analysis of its prestellar core population , 2015, 1502.05858.

[16]  Y. Shirley.  The Critical Density and the Effective Excitation Density of Commonly Observed Molecular Dense Gas Tracers , 2015, 1501.01629.

[17]  G. W. Pratt,et al.  Planck intermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence , 2014, 1405.0872.

[18]  K. Menten,et al.  SUBMILLIMETER ARRAY OBSERVATIONS OF MAGNETIC FIELDS IN G240.31+0.07: AN HOURGLASS IN A MASSIVE CLUSTER-FORMING CORE , 2014, 1409.5608.

[19]  Astronomy,et al.  On the radiation driven alignment of dust grains: Detection of the polarization hole in a starless core , 2014, 1408.5133.

[20]  M. Wright,et al.  TADPOL: A 1.3 mm SURVEY OF DUST POLARIZATION IN STAR-FORMING CORES AND REGIONS , 2013, 1310.6653.

[21]  N. Peretto,et al.  Reconstructing the density and temperature structure of prestellar cores from Herschel data: A case study for B68 and L1689B , 2013, 1311.5086.

[22]  A. Roman-Lopes,et al.  OPTICAL/NEAR-INFRARED POLARIZATION SURVEY OF Sh 2-29: MAGNETIC FIELDS, DENSE CLOUD FRAGMENTATIONS, AND ANOMALOUS DUST GRAIN SIZES , 2013, 1310.7037.

[23]  David Berry,et al.  SMURF: SubMillimeter User Reduction Facility , 2013 .

[24]  Prasanth H. Nair,et al.  Astropy: A community Python package for astronomy , 2013, 1307.6212.

[25]  C. Hull,et al.  THE MAGNETIC FIELD MORPHOLOGY OF THE CLASS 0 PROTOSTAR L1157-mm , 2013, 1304.6739.

[26]  Canadian Institute for Theoretical Astrophysics,et al.  First results from the Herschel Gould Belt Survey in Taurus , 2013, 1304.4098.

[27]  C. B. Netterfield,et al.  AN IMPRINT OF MOLECULAR CLOUD MAGNETIZATION IN THE MORPHOLOGY OF THE DUST POLARIZED EMISSION , 2013, 1303.1830.

[28]  P. A. R. Ade,et al.  SCUBA-2: the 10 000 pixel bolometer camera on the James Clerk Maxwell Telescope , 2013, 1301.3650.

[29]  Per Friberg,et al.  Scuba-2: On-sky calibration using submillimetre standard sources , 2013, 1301.3773.

[30]  T. Robitaille,et al.  APLpy: Astronomical Plotting Library in Python , 2012 .

[31]  P. Koch,et al.  MAGNETIC FIELD PROPERTIES IN HIGH-MASS STAR FORMATION FROM LARGE TO SMALL SCALES: A STATISTICAL ANALYSIS FROM POLARIZATION DATA , 2010, 1008.0220.

[32]  P. Bastien,et al.  MAGNETIC FIELD STRUCTURES AND TURBULENT COMPONENTS IN THE STAR-FORMING MOLECULAR CLOUDS OMC-2 AND OMC-3 , 2010, 1003.5596.

[33]  Jessie L. Dotson,et al.  350 μm POLARIMETRY FROM THE CALTECH SUBMILLIMETER OBSERVATORY , 2010, 1001.2790.

[34]  D. Marrone,et al.  IRAS 16293: A “MAGNETIC” TALE OF TWO CORES , 2009, 0910.5269.

[35]  Qizhou Zhang,et al.  Magnetic Fields in the Formation of Massive Stars , 2009, Science.

[36]  India,et al.  Optical and submillimetre observations of Bok globules – tracing the magnetic field from low to high density , 2009, 0906.0248.

[37]  Brenda C. Matthews,et al.  THE LEGACY OF SCUPOL: 850 μm IMAGING POLARIMETRY FROM 1997 TO 2005 , 2009 .

[38]  N. Evans,et al.  PROPERTIES OF THE YOUNGEST PROTOSTARS IN PERSEUS, SERPENS, AND OPHIUCHUS , 2008, 0809.4012.

[39]  J. Dotson,et al.  DISPERSION OF MAGNETIC FIELDS IN MOLECULAR CLOUDS. I , 2009 .

[40]  Jessie L. Dotson,et al.  DISPERSION OF MAGNETIC FIELDS IN MOLECULAR CLOUDS. II. , 2008, 0909.5227.

[41]  G. Kowal,et al.  Studies of Regular and Random Magnetic Fields in the ISM: Statistics of Polarization Vectors and the Chandrasekhar-Fermi Technique , 2008, 0801.0279.

[42]  A. Whitworth,et al.  The James Clerk Maxwell Telescope Legacy Survey of Nearby Star‐forming Regions in the Gould Belt , 2007, 0707.0169.

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

[44]  A. Lazarian,et al.  Radiative torques: analytical model and basic properties , 2007, 0707.0886.

[45]  N. Peretto,et al.  The initial conditions of star formation in the Ophiuchus main cloud: Kinematics of the protocluster condensations , , 2007, 0706.1535.

[46]  A. Whitworth,et al.  The dust temperatures of the pre-stellar cores in the ρ Oph main cloud and in other star-forming regions: consequences for the core mass function , 2007, 0705.2941.

[47]  Ramprasad Rao,et al.  Magnetic Fields in the Formation of Sun-Like Stars , 2006, Science.

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

[49]  C. Aspin,et al.  Astronomical Polarimetry: Current Status and Future Directions , 2005 .

[50]  K. Tassis,et al.  Observational Constraints on the Ages of Molecular Clouds and the Star Formation Timescale: Ambipolar-Diffusion-controlled or Turbulence-induced Star Formation? , 2005, astro-ph/0512043.

[51]  D. Ward-Thompson,et al.  SCUBA Polarization Measurements of the Magnetic Field Strengths in the L183, L1544, and L43 Prestellar Cores , 2003, astro-ph/0305604.

[52]  M. Juvela,et al.  Theoretical Models of Polarized Dust Emission from Protostellar Cores , 2001, astro-ph/0104231.

[53]  M. Norman,et al.  Magnetic Field Diagnostics Based on Far-Infrared Polarimetry: Tests Using Numerical Simulations , 2001, astro-ph/0103286.

[54]  James M. Stone,et al.  Density, Velocity, and Magnetic Field Structure in Turbulent Molecular Cloud Models , 2000, astro-ph/0008454.

[55]  W. Holland,et al.  First Observations of the Magnetic Field Geometry in Prestellar Cores , 2000, astro-ph/0006069.

[56]  J. Girart,et al.  Detection of Polarized CO Emission from the Molecular Outflow in NGC 1333 IRAS 4A , 1999, The Astrophysical journal.

[57]  R. Crutcher.  Magnetic fields in molecular clouds , 2007 .

[58]  F. Shu,et al.  Collapse of magnetized molecular cloud cores. I: Semianalytical solution , 1993 .

[59]  F. Shu,et al.  Collapse of Magnetized Molecular Cloud Cores. II. Numerical Results , 1993 .

[60]  Alyssa A. Goodman,et al.  OH Zeeman observations of dark clouds , 1993 .

[61]  Steven V. W. Beckwith,et al.  Particle Emissivity in Circumstellar Disks , 1991 .

[62]  A. Wootten,et al.  Cold DCO(+) cores and protostars in the warm Rho Ophiuchi cloud , 1990 .

[63]  F. Vrba.  Role of magnetic fields in the evolution of five dark cloud complexes , 1977 .

[64]  Enrico Fermi,et al.  Magnetic fields in spiral arms , 1953 .

[65]  W. A. Hiltner,et al.  Polarization of Light From Distant Stars by Interstellar Medium. , 1949, Science.

[66]  J S Hall,et al.  Observations of the Polarized Light From Stars. , 1949, Science.