J/ApJ/793/126ivo://CDS.VizieR/J/ApJ/793/126doi:10.26093/cds/vizier.17930126CDSCashman L.R.Clemens D.P.2017-06-21T07:19:48Z2017-05-12T15:50:31ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyinterstellar-mediummolecular-cloudspolarimetryinfrared-photometryextinctionThe L204 dark cloud complex is a nearby filamentary structure in Ophiuchus North that has no signs of active star formation. Past studies show that L204 is interacting with the nearby runaway O star, {zeta} Oph, and hosts a magnetic field that is coherent across parsec-length scales. Near-infrared H-band (1.6 {mu}m) linear polarization measurements were obtained for 3896 background stars across a 1{deg}x1.5{deg} region centered on the dense Cloud 3 in L204, using the Mimir near-infrared instrument on the 1.8 m Perkins Telescope. Analysis of these observations reveals both large-scale properties and small-scale changes in the magnetic field direction in Cloud 3. In the northern and western {zeta} Oph facing regions of the cloud, the magnetic field appears to be pushed up against the face of the cloud. This may indicate that the UV flux from {zeta} Oph has compressed the magnetic field on the western edge of L204. The plane-of-sky magnetic field strength is estimated to be ~11-26 {mu}G using the Chandrasekhar-Fermi method. The polarimetry data also reveal that the polarization efficiency (PE {equiv} P_H_/A_V_) steadily decreases with distance from {zeta} Oph (-0.09%+/-0.03%/mag/pc). Additionally, power-law fits of PE versus A_V_ for localized samples of probe stars show steeper negative indices with distance from {zeta} Oph. Both findings highlight the importance of external illumination, here from {zeta} Oph, in aligning dust grains to embedded magnetic fields.2014ApJ...793..126Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/793/126CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/141/175 : Dark clouds imaging polarimetry (Sen+, 2000)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/793/126https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/793/126http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/793/126https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/793/126https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/793/126http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/793/126GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/793/126/table1 (Polarimetry and Photometry of 7150 Stars Towards L204 - Cloud 3)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/793/126/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/793/126/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/793/126/table1?GETtext/xml+votable180.050000true251.517917-11.5716670.0055555555555555565/7698 6/30786 30787 307961.1166583743361574e-19 1.7003137259100215e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/793/126?format=asciiInfrareddefaultJ/ApJ/793/126/table1Polarimetry and Photometry of 7150 Stars Towards L204 - Cloud 3recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/7150] Star index numbermeta.id;meta.mainintRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainUStokes U Mimir measurement%phys.polarization.stokes;arith.ratiofloate_UUncertainty in U%stat.error;pos.cartesian.xfloatQStokes Q Mimir measurement%phys.polarization.stokes;arith.ratiofloate_QUncertainty in Q%stat.errorfloatPDegree of polarization (1)%phys.polarizationfloate_PUncertainty in P%stat.errorfloatPAEquatorial position angle; measured East of Northdegpos.posAnginte_PAUncertainty in PAdegstat.errorintUFlag[1/3] Usage flag (2)meta.codeintl_Jmag[<] Upper limit flag on Jmagmeta.code.errorcharJmag? 2MASS J band magnitude (3)magphot.mag;em.IR.Jfloatnullablee_Jmag? Uncertainty in Jmag (3)magstat.error;phot.mag;em.IR.JfloatnullableHmag? 2MASS H band magnitude (3)magphot.mag;em.IR.Hfloatnullablee_Hmag? Uncertainty in Hmag (3)magstat.error;phot.mag;em.IR.Hfloatnullablel_Ksmag[<] Upper limit flag on Ksmagmeta.code.errorcharKsmag? 2MASS K_S_ band magnitude (3)magphot.mag;em.IR.Kfloatnullablee_Ksmag? Uncertainty in Ksmag (3)magstat.error;phot.mag;em.IR.KfloatnullableBFlag[0/2] Background flag (4)meta.codecharAV? The V band extinction (5)magphys.absorption;em.opt.Vfloatnullablee_AV? Uncertainty in AVmagstat.errorfloatnullable