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The JCMT BISTRO Survey: The Magnetic Field Strength in the Orion A Filament
Pattle, Kate,Ward-Thompson, Derek,Berry, David,Hatchell, Jennifer,Chen, Huei-Ru,Pon, Andy,Koch, Patrick M.,Kwon, Woojin,Kim, Jongsoo,Bastien, Pierre,Cho, Jungyeon,Coudé,, Simon,Di Francesco, Jam American Astronomical Society 2017 The Astrophysical journal Vol.846 No.2
<P>We determine the magnetic field strength in the OMC. 1 region of the Orion A filament via a new implementation of the Chandrasekhar-Fermi method using observations performed as part of the James Clerk Maxwell Telescope (JCMT) B-Fields In Star-forming Region Observations (BISTRO) survey with the POL-2 instrument. We combine BISTRO data with archival SCUBA-2 and HARP observations to find a plane-of-sky magnetic field strength in OMC. 1 of B-pos= 6.6 +/- 4.7 mG, where delta B-pos = 4.7 mG represents a predominantly systematic uncertainty. We develop a new method for measuring angular dispersion, analogous to unsharp masking. We find a magnetic energy density of similar to 1.7 x 10(-7) J m(-3) in OMC. 1, comparable both to the gravitational potential energy density of OMC 1 (similar to 10(-7) J m(-3)) and to the energy density in the Orion BN/KL outflow (similar to 10(-7) J m(-3)). We find that neither the Alfven velocity in OMC. 1 nor the velocity of the super-Alfvenic outflow ejecta is sufficiently large for the BN/KL outflow to have caused large-scale distortion of the local magnetic field in the similar to 500 yr lifetime of the outflow. Hence, we propose that the hourglass field morphology in OMC. 1 is caused by the distortion of a primordial cylindrically symmetric magnetic field by the gravitational fragmentation of the filament and/or the gravitational interaction of the BN/KL and S clumps. We find that OMC. 1 is currently in or near magnetically supported equilibrium, and that the current large-scale morphology of the BN/KL outflow is regulated by the geometry of the magnetic field in OMC 1, and not vice versa.</P>
Magnetic Fields toward Ophiuchus-B Derived from SCUBA-2 Polarization Measurements
Soam, Archana,Pattle, Kate,Ward-Thompson, Derek,Lee, Chang Won,Sadavoy, Sarah,Koch, Patrick M.,Kim, Gwanjeong,Kwon, Jungmi,Kwon, Woojin,Arzoumanian, Doris,Berry, David,Hoang, Thiem,Tamura, Motohide,Le American Astronomical Society 2018 The Astrophysical journal Vol.861 No.1
<P>We present the results of dust emission polarization measurements of Ophiuchus-B (Oph-B) carried out using the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) camera with its associated polarimeter (POL-2) on the James Clerk Maxwell Telescope in Hawaii. This work is part of the B-fields in Star-forming Region Observations survey initiated to understand the role of magnetic fields in star formation for nearby star-forming molecular clouds. We present a first look at the geometry and strength of magnetic fields in Oph-B. The field geometry is traced over similar to 0.2 pc, with clear detection of both of the sub-clumps of Oph-B. The field pattern appears significantly disordered in sub-clump Oph-B1. The field geometry in Oph-B2 is more ordered, with a tendency to be along the major axis of the clump, parallel to the filamentary structure within which it lies. The degree of polarization decreases systematically toward the dense core material in the two sub-clumps. The field lines in the lower density material along the periphery are smoothly joined to the large-scale magnetic fields probed by NIR polarization observations. We estimated a magnetic field strength of 630 +/- 410 mu G in the Oph-B2 sub-clump using a Davis-Chandrasekhar-Fermi analysis. With this magnetic field strength, we find a mass-to-flux ratio lambda = 1.6 +/- 1.1, which suggests that the Oph-B2 clump is slightly magnetically supercritical.</P>
First Results from BISTRO: A SCUBA-2 Polarimeter Survey of the Gould Belt
Ward-Thompson, Derek,Pattle, Kate,Bastien, Pierre,Furuya, Ray S.,Kwon, Woojin,Lai, Shih-Ping,Qiu, Keping,Berry, David,Choi, Minho,Coudé,, Simon,Francesco, James Di,Hoang, Thiem,Franzmann, Erica American Astronomical Society 2017 The Astrophysical Journal Vol.842 No.1
<P>We present the first results from the B-fields In STar-forming Region Observations (BISTRO) survey, using the Sub-millimetre Common-User Bolometer Array. 2 camera, with its associated polarimeter (POL-2), on the James Clerk Maxwell Telescope in Hawaii. We discuss the survey's aims and objectives. We describe the rationale behind the survey, and the questions that. the survey will aim to answer. The most important of these is the role of magnetic fields in the star formation process on the scale of individual filaments and cores in dense regions. We describe the data acquisition and reduction processes for POL-2, demonstrating both repeatability and consistency with previous data. We present a first-look analysis of the first results from the BISTRO survey in the OMC 1 region. We see that the magnetic field lies approximately perpendicular to the famous 'integral filament' in the densest regions of that filament. Furthermore, we see an 'hourglass' magnetic field morphology extending beyond the densest region of the integral filament into the less-dense surrounding material, and discuss possible causes for this. We also discuss the more complex morphology seen along the Orion Bar region. We examine the morphology of the field along the lower-density northeastern filament. We find consistency with previous theoretical models that predict magnetic fields lying parallel to low-density, non-self-gravitating filaments, and perpendicular to higher-density, self-gravitating filaments.</P>
AKARI, SCUBA2 AND HERSCHEL DATA OF PRE-STELLAR CORES
D. Ward-Thompson,K. Pattle,J. M. Kirk,P. Andre,J. Di Francesco 한국천문학회 2017 天文學論叢 Vol.32 No.1
We show Akari data, Herschel data and data from the SCUBA2 cameraon JCMT, of molecular clouds. We focus on pre-stellar cores within the clouds. We present Akari data of the L1147-1157 ring in Cepheus and show how thedata indicate that the cores are being externally heated. We present SCUBA2and Herschel data of the Ophiuchus region and show how the environment isalso affecting core evolution in this region. We discuss the effects of the magnetic field in the Lupus I region, andhow this lends support to a model for the formation and evolution of coresin filamentary molecular clouds.
<i>Herschel</i> and SCUBA-2 observations of dust emission in a sample of <i>Planck</i> cold clumps
Juvela, Mika,He, Jinhua,Pattle, Katherine,Liu, Tie,Bendo, George,Eden, David J.,Fehé,r, Orsolya,Michel, Fich,Fuller, Gary,Hirano, Naomi,Kim, Kee-Tae,Li, Di,Liu, Sheng-Yuan,Malinen, Johanna,Marsh Springer-Verlag 2018 Astronomy and astrophysics Vol.612 No.-
<P><I>Context.</I> Analysis of all-sky <I>Planck</I> submillimetre observations and the IRAS 100 <I>μ</I>m data has led to the detection of a population of Galactic cold clumps. The clumps can be used to study star formation and dust properties in a wide range of Galactic environments.</P><P><I>Aims.</I> Our aim is to measure dust spectral energy distribution (SED) variations as a function of the spatial scale and the wavelength.</P><P><I>Methods.</I> We examined the SEDs at large scales using IRAS, <I>Planck</I>, and <I>Herschel</I> data. At smaller scales, we compared JCMT/SCUBA-2 850 <I>μ</I>m maps with <I>Herschel</I> data that were filtered using the SCUBA-2 pipeline. Clumps were extracted using the Fellwalker method, and their spectra were modelled as modified blackbody functions.</P><P><I>Results.</I> According to IRAS and <I>Planck</I> data, most fields have dust colour temperatures <I>T</I>C ~ 14-18 K and opacity spectral index values of <I>β</I> = 1.5-1.9. The clumps and cores identified in SCUBA-2 maps have <I>T</I> ~ 13 K and similar <I>β</I> values. There are some indications of the dust emission spectrum becoming flatter at wavelengths longer than 500 <I>μ</I>m. In fits involving <I>Planck</I> data, the significance is limited by the uncertainty of the corrections for CO line contamination. The fits to the SPIRE data give a median <I>β</I> value that is slightly above 1.8. In the joint SPIRE and SCUBA-2 850 <I>μ</I>m fits, the value decreases to <I>β</I> ~ 1.6. Most of the observed <I>T</I>-<I>β</I> anticorrelation can be explained by noise.</P><P><I>Conclusions.</I> The typical submillimetre opacity spectral index <I>β</I> of cold clumps is found to be ~1.7. This is above the values of diffuse clouds, but lower than in some previous studies of dense clumps. There is only tentative evidence of a <I>T</I>-<I>β</I> anticorrelation and <I>β</I> decreasing at millimetre wavelengths.</P>
A First Look at BISTRO Observations of the <i>ρ</i> Oph-A core
Kwon, Jungmi,Doi, Yasuo,Tamura, Motohide,Matsumura, Masafumi,Pattle, Kate,Berry, David,Sadavoy, Sarah,Matthews, Brenda C.,Ward-Thompson, Derek,Hasegawa, Tetsuo,Furuya, Ray S.,Pon, Andy,Francesco, Jame American Astronomical Society 2018 The Astrophysical Journal Vol.859 No.1
Far-infrared observations of a massive cluster forming in the Monoceros R2 filament hub
Rayner, T. S. M.,Griffin, M. J.,Schneider, N.,Motte, F.,Kö,nyves, V.,André,, P.,Di Francesco, J.,Didelon, P.,Pattle, K.,Ward-Thompson, D.,Anderson, L. D.,Benedettini, M.,Bernard, J.-P.,Bonte Springer-Verlag 2017 Astronomy and astrophysics Vol.607 No.-