J/ApJ/842/L9ivo://CDS.VizieR/J/ApJ/842/L9doi:10.26093/cds/vizier.18429009CDSHull C.L.H.Mocz P.Burkhart B.Goodman A.A.Girart J.M.Cortes P.C.,Hernquist L.Springel V.Li Z.-Y.Lai S.-P.2018-05-14T09:31:04Z2018-03-07T08:23:51ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frpolarimetryyoung-stellar-objectsinterstellar-mediummagnetic-fieldsmillimeter-astronomysubmillimeter-astronomyWe report Atacama Large Millimeter/submillimeter Array (ALMA) observations of polarized dust emission from the protostellar source Ser-emb 8 at a linear resolution of 140au. Assuming models of dust-grain alignment hold, the observed polarization pattern gives a projected view of the magnetic field structure in this source. Contrary to expectations based on models of strongly magnetized star formation, the magnetic field in Ser-emb 8 does not exhibit an hourglass morphology. Combining the new ALMA data with previous observational studies, we can connect magnetic field structure from protostellar core (~80000au) to disk (~100au) scales. We compare our observations with four magnetohydrodynamic gravo-turbulence simulations made with the AREPO code that have initial conditions ranging from super-Alfvenic (weakly magnetized) to sub-Alfvenic (strongly magnetized). These simulations achieve the spatial dynamic range necessary to resolve the collapse of protostars from the parsec scale of star-forming clouds down to the ~100au scale probed by ALMA. Only in the very strongly magnetized simulation do we see both the preservation of the field direction from cloud to disk scales and an hourglass-shaped field at <1000au scales. We conduct an analysis of the relative orientation of the magnetic field and the density structure in both the Ser-emb 8 ALMA observations and the synthetic observations of the four AREPO simulations. We conclude that the Ser-emb 8 data are most similar to the weakly magnetized simulations, which exhibit random alignment, in contrast to the strongly magnetized simulation, where the magnetic field plays a role in shaping the density structure in the source. In the weak-field case, it is turbulence-not the magnetic field-that shapes the material that forms the protostar, highlighting the dominant role that turbulence can play across many orders of magnitude in spatial scale.2017ApJ...842L...9Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/842/L9CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/603/584 : Polarimetry toward Musca dark cloud (Pereyra+, 2004)J/ApJ/692/973 : Protostars in Perseus, Serpens and Ophiuchus (Enoch+, 2009)J/ApJS/182/143 : SCUPOL Legacy polarimetry of SCUBA (Matthews+, 2009)J/ApJS/186/406 : 350um polarimetry from CSO (Dotson+, 2010)J/A+A/569/L1 : Polarization hole in a starless core (Alves+, 2014)J/ApJS/213/13 : Polarization maps of star-forming cores & SFRs (Hull+, 2014)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/842/L9https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/842/L9http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/842/L9https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/842/L9https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/842/L9http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/842/L9GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/842/L9/table2 (870um (Band 7) ALMA data)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/842/L9/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/842/L9/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/842/L9/table2?GETtext/xml+votable180.050000true277.450931.277770.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/ApJ/842/L96/30366https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/842/L9?format=asciiRadiodefaultJ/ApJ/842/L9/table2870um (Band 7) ALMA datarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainchi[0.4/178] Orientation of the magnetic field, measured counterclockwise from northdegpos.posAngfloate_chi[1.2/9.5] Uncertainty in chidegstat.errorfloatPInt[0.07/0.6] Polarized intensitymJy/beamphot.flux.densityfloatInt? Total Intensity (1)mJy/beamphys.polarization.stokesfloatnullable