IRAS 16293: A “MAGNETIC” TALE OF TWO CORES

We present polarization observations of the dust continuum emission from the young star-forming region IRAS 16293. These observations of IRAS 16293, which is a binary system, were conducted by the Submillimeter Array at an observing frequency of 341.5 GHz (λ ∼  880 μm) and with high angular resolution (∼2″–3″). We find that the large-scale global direction of the field, which is perpendicular to the observed polarization, appears to be along the dust ridge where the emission peaks. On smaller scales we find that the field structure is significantly different for the two components of the binary. The first component, source A, shows a magnetic field structure that is “hourglass” shaped as predicted from theoretical models of low-mass star formation in the presence of strong magnetic fields. However, the other component, source B, shows a relatively ordered magnetic field with no evidence of any deformation. We have possibly detected a third younger outflow from source A as seen in the SiO emission, which is in addition to the two well-known powerful bipolar outflows in this kinematically active region. There is an observed decrease in polarization toward the center and this “polarization hole” is similar to decreases seen in other young star-forming regions. Our calculations show that in IRAS 16293 the magnetic energy is stronger than the turbulent energy but is approximately similar to the centrifugal energy. There is a considerable misalignment between the outflow direction and the magnetic field axis, and this is roughly in agreement with model predictions where the magnetic energy is comparable to the centrifugal energy. In conjunction with other observations of the kinematics as determined from the outflow energetics and chemical differentiation, we find that our results provide additional evidence to show that the two protostars appear to be in different stages during their evolution.

[1]  M. Houde,et al.  MAGNETIC FIELDS AND INFALL MOTIONS IN NGC 1333 IRAS 4 , 2009, 0907.1301.

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

[3]  P. Koch,et al.  EVOLUTION OF MAGNETIC FIELDS IN HIGH-MASS STAR FORMATION: LINKING FIELD GEOMETRY AND COLLAPSE FOR THE W51 e2/e8 CORES , 2009, 0905.1996.

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

[5]  A. Lazarian,et al.  GRAIN ALIGNMENT INDUCED BY RADIATIVE TORQUES: EFFECTS OF INTERNAL RELAXATION OF ENERGY AND COMPLEX RADIATION FIELD , 2008, 0812.4576.

[6]  P. Koch,et al.  EVOLUTION OF MAGNETIC FIELDS IN HIGH MASS STAR FORMATION: SUBMILLIMETER ARRAY DUST POLARIZATION IMAGE OF THE ULTRACOMPACT H ii REGION G5.89−0.39 , 2008, 0812.3444.

[7]  D. Padgett,et al.  THE SPITZER c2d LEGACY RESULTS: STAR-FORMATION RATES AND EFFICIENCIES; EVOLUTION AND LIFETIMES , 2008, 0811.1059.

[8]  Richard M. Crutcher,et al.  TESTING MAGNETIC STAR FORMATION THEORY , 2008, 0807.2862.

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

[10]  J. Girart,et al.  Modeling the magnetic field in the protostellar source NGC 1333 IRAS 4A , 2008, 0809.5278.

[11]  Daniel P. Marrone,et al.  The submillimeter array polarimeter , 2008, Astronomical Telescopes + Instrumentation.

[12]  S. Bottinelli,et al.  An interferometric study of the low-mass protostar IRAS 16293-2422: small scale organic chemistry , 2008, 0807.1447.

[13]  F. O. Alves,et al.  Optical polarimetry toward the Pipe nebula: revealing the importance of the magnetic field , 2008, 0806.1189.

[14]  E. Ostriker,et al.  Magnetically Aligned Velocity Anisotropy in the Taurus Molecular Cloud , 2008, 0802.2084.

[15]  L. Loinard,et al.  A Preliminary VLBA Distance to the Core of Ophiuchus, with an Accuracy of 4% , 2008, 0801.2192.

[16]  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.

[17]  P. Ho,et al.  The CO Molecular Outflows of IRAS 16293–2422 Probed by the Submillimeter Array , 2007, 0710.2635.

[18]  S. Sakai,et al.  Astrometry of H$_2$O Masers in Nearby Star-Forming Regions with VERA I. IRAS 16293$-$2422 in $\rho$ Oph East , 2007 .

[19]  D. Padgett,et al.  The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. VII. Ophiuchus Observed with MIPS , 2007, 0709.3492.

[20]  C. Brogan,et al.  New Radio Sources and the Composite Structure of Component B in the Very Young Protostellar System IRAS 16293–2422 , 2007, 0708.2420.

[21]  G. Novak,et al.  DISPERSION OF OBSERVED POSITION ANGLES OF SUBMILLIMETER POLARIZATION IN MOLECULAR CLOUDS , 2007, 0707.2818.

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

[23]  A. Lazarian,et al.  Radiative torque alignment: essential physical processes , 2007, 0707.3645.

[24]  D. Wilner,et al.  Arcsecond-Resolution Submillimeter HCN Imaging of the Binary Protostar IRAS 16293–2422 , 2007, astro-ph/0702526.

[25]  Qizhou Zhang,et al.  PROSAC: A Submillimeter Array Survey of Low-Mass Protostars. I. Overview of Program: Envelopes, Disks, Outflows, and Hot Cores , 2007, astro-ph/0701115.

[26]  Immo Appenzeller,et al.  Star-disk interaction in young stars : proceedings of the 243th symposium of the International Astronomical Union held in Grenoble, France, May 21-25, 2007 , 2007 .

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

[28]  P. Bastien,et al.  Comparison of Magnetic Field Structures on Different Scales in and around the Filamentary Dark Cloud GF 9 , 2006, astro-ph/0608188.

[29]  F. Shu,et al.  Gravitational Collapse of Magnetized Clouds. I. Ideal Magnetohydrodynamic Accretion Flow , 2006, astro-ph/0604573.

[30]  P. Andre',et al.  A SCUBA survey of L1689 ¿ the dog that didn't bark , 2006, astro-ph/0603203.

[31]  T. Hanawa,et al.  Evolution of Rotating Molecular Cloud Core with Oblique Magnetic Field , 2006, astro-ph/0602034.

[32]  J. M. Hollis,et al.  IRAS 16293–2422: Evidence for Infall onto a Counterrotating Protostellar Accretion Disk , 2005, astro-ph/0512225.

[33]  J. M. Moran,et al.  Interferometric Measurements of Variable 340 GHz Linear Polarization in Sagittarius A* , 2005, astro-ph/0511653.

[34]  Ralph E. Pudritz,et al.  Outflows and Jets from Collapsing Magnetized Cloud Cores , 2005, astro-ph/0508374.

[35]  K. Tomisaka,et al.  Alignment of Outflows with Magnetic Fields in Cloud Cores , 2005, astro-ph/0512581.

[36]  Qizhou Zhang,et al.  SiO J = 5-4 in the HH 211 Protostellar Jet Imaged with the Submillimeter Array , 2005, astro-ph/0512252.

[37]  T. Hanawa,et al.  Collapse and fragmentation of rotating magnetized clouds — I. Magnetic flux-spin relation , 2005, astro-ph/0506439.

[38]  C. Brogan,et al.  IRAS 16293–2422: Proper Motions, Jet Precession, the Hot Core, and the Unambiguous Detection of Infall , 2005, astro-ph/0506435.

[39]  W. D. Watson,et al.  Line Polarization of Molecular Lines at Radio Frequencies: The Case of DR 21(OH) , 2005, astro-ph/0504258.

[40]  L. Loinard,et al.  IRAS 16293–2422B: A Compact, Possibly Isolated Protoplanetary Disk in a Class 0 Object , 2005, astro-ph/0501621.

[41]  Cecilia Ceccarelli,et al.  Near-Arcsecond Resolution Observations of the Hot Corino of the Solar-Type Protostar IRAS 16293–2422 , 2004, astro-ph/0410601.

[42]  ASIAA,et al.  Organic Molecules in Low-Mass Protostellar Hot Cores: Submillimeter Imaging of IRAS 16293–2422 , 2004, astro-ph/0410027.

[43]  K. Tomisaka,et al.  Directions of Outflows, Disks, Magnetic Fields, and Rotation of Young Stellar Objects in Collapsing Molecular Cloud Cores , 2004, astro-ph/0408086.

[44]  M. Griffin,et al.  The circumstellar environment of IRAS 16293-2422 ISO-LWS and SCUBA observations , 2004 .

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

[46]  Antonio Pereyra,et al.  Polarimetry toward the Musca Dark Cloud. I. The Catalog , 2004 .

[47]  G. Melnick,et al.  Probing the Early Stages of Low-Mass Star Formation in LDN 1689N: Dust and Water in IRAS 16293–2422A, B, and E , 2004, astro-ph/0402604.

[48]  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.

[49]  D. Teyssier,et al.  The Hot Core around the Low-Mass Protostar IRAS 16293–2422: Scoundrels Rule! , 2003 .

[50]  J. Girart,et al.  Interferometric Mapping of Magnetic Fields in Star-forming Regions. III. Dust and CO Polarization in DR 21(OH) , 2003, astro-ph/0308051.

[51]  E. F. Dishoeck,et al.  Does IRAS 16293–2422 have a hot core? Chemical inventory and abundance changes in its protostellar environment , 2002, astro-ph/0205457.

[52]  J. Girart,et al.  Interferometric Mapping of Magnetic Fields in Star-forming Regions. II. NGC 2024 FIR 5 , 2001, astro-ph/0110682.

[53]  Astrophysics,et al.  Infall, Outflow, Rotation, and Turbulent Motions of Dense Gas within NGC 1333 IRAS 4 , 2001, astro-ph/0108022.

[54]  B. Matthews,et al.  Magnetic Fields in Star-forming Molecular Clouds. II. The Depolarization Effect in the OMC-3 Filament of Orion A , 2001, astro-ph/0106394.

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

[56]  T. Umemoto,et al.  SiO Emission in the Multilobe Outflow Associated with IRAS 16293–2422 , 2000, astro-ph/0010013.

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

[58]  Gautier Mathys,et al.  Magnetic Fields Across the Hertzsprung-Russell Diagram , 2001 .

[59]  J. Girart,et al.  Interferometric Mapping of Magnetic Fields in Star-forming Regions. I. W51 e1/e2 Molecular Cores , 2000, astro-ph/0107322.

[60]  F. Ménard,et al.  Near-Infrared Imaging Polarimetry of the GG Tauri Circumbinary Ring , 2000, The Astrophysical journal.

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

[62]  R. Klessen,et al.  Control of star formation by supersonic turbulence , 2000, astro-ph/0301093.

[63]  Lee G. Mundy,et al.  Unveiling the Circumstellar Envelope and Disk: A Subarcsecond Survey of Circumstellar Structures , 1999, astro-ph/9908301.

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

[65]  James M. Moran,et al.  The Submillimeter Array , 2004, Astronomical Telescopes and Instrumentation.

[66]  M. Wright,et al.  High-Resolution Millimeter-Wave Mapping of Linearly Polarized Dust Emission: Magnetic Field Structure in Orion , 1998, astro-ph/9805288.

[67]  C. Walker,et al.  The “Blue-Bulge” Infall Signature toward IRAS 16293–2422 , 1998 .

[68]  John E. Carlstrom,et al.  Magnetic Field Structure in Protostellar Envelopes , 1997 .

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

[70]  L. Mundy,et al.  Molecular abundances and low-mass star formation. 1: Si- and S-bearing species toward IRAS 16293-2422 , 1994 .

[71]  A. Goodman,et al.  THE MAGNETIC FIELD IN THE OPHIUCHUS DARK CLOUD COMPLEX , 1994 .

[72]  P. Andre',et al.  From T Tauri stars to protostars: Circumstellar material and young stellar objects in the rho Ophiuchi cloud , 1994 .

[73]  P. Andre',et al.  Submillimeter Continuum Observations of rho Ophiuchi A: The Candidate Protostar VLA 1623 and Prestellar Clumps , 1993 .

[74]  J. Hough,et al.  Magnetic field in a low-mass protostar disk - Millimeter polarimetry of IRAS 16293-2422 , 1993 .

[75]  M. Wright,et al.  Mapping Cygnus A at 3 millimeter wavelength with the MIRIAD system , 1993 .

[76]  S. Basu,et al.  Magnetic braking, ambipolar diffusion, and the formation of cloud cores and protostars. I. Axisymmetric solutions , 1994 .

[77]  E. I. Robson,et al.  NGC 1333 IRAS 4 : a very young, low-luminosity binary system , 1991 .

[78]  T. Mouschovias.  Magnetic braking, ambipolar diffusion, cloud cores, and star formation: Natural length scales and protostellar masses , 1991 .

[79]  G. Garay,et al.  Multifrequency VLA observations of radio continuum from IRAS 16293 - 2422 , 1991 .

[80]  A. M. Flett,et al.  First results from a submillimetre polarimeter on the James Clerk Maxwell Telescope , 1991 .

[81]  J. Carlstrom,et al.  Observations of the dense gas in the IRAS 16293-2422 outflow system , 1990 .

[82]  S. Nozawa,et al.  A Remarkable Multilobe Molecular Outflow: rho Ophiuchi East, Associated with IRAS 16293-2422 , 1990 .

[83]  L. Mundy,et al.  The circumstellar structure of IRAS 16293-2422 - (C-18)O, NH3, and CO observations , 1990 .

[84]  E. Young,et al.  IRAS Observations of the Rho Ophiuchi Infrared Cluster: Spectral Energy Distributions and Luminosity Function , 1989 .

[85]  A. Wootten.  The Duplicity of IRAS 16293-2422: A Protobinary Star? , 1989 .

[86]  E. Young,et al.  An Unusual Outflow around IRAS 16293-2422 , 1988 .

[87]  M. Tamura,et al.  Infrared polarimetry of dark clouds – II. Magnetic field structure in the ρ Ophiuchi dark cloud , 1988 .

[88]  M. Peimbert,et al.  Star Forming Regions , 1987 .

[89]  E. Young,et al.  Spectroscopic Evidence for Infall around an Extraordinary IRAS Source in Ophiuchus , 1986 .

[90]  G. Rieke,et al.  Infrared polarimetry in the rho Ophiuchus dark cloud. , 1979 .

[91]  L. Spitzer,et al.  Note on the collapse of magnetic interstellar clouds. , 1976 .

[92]  F. Vrba,et al.  Magnetic field structure in the vicinity of five dark cloud complexes. , 1976 .

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

[94]  J. Greenstein,et al.  The Polarization of Starlight by Aligned Dust Grains. , 1951 .