J/A+A/665/A77ivo://CDS.VizieR/J/A+A/665/A77doi:10.26093/cds/vizier.36650077CDSSkalidis R.Tassis K.Panopoulou G.V.Pineda J.L.Gong Y.,Mandarakas N.Blinov D.Kiehlmann S.Kypriotakis J.A.2022-09-19T10:15:55Z2022-09-14T12:46:34ZCDS support team

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

cds-question@unistra.frpolarimetryinterstellar-mediummagnetic-fieldsAtomic gas in the diffuse interstellar medium (ISM) is organized in filamentary structures. These structures usually host cold and dense molecular clumps. The Galactic magnetic field is considered to play an important role in the formation of these clumps. Our goal is to explore the role of the magnetic field in the HI-H_2_ transition process. We targeted a filamentary cloud where gas transitions from atomic to molecular. This cloud is located at the edges of an expanding structure, known as the North Celestial Pole Loop (NCPL). We probed the magnetic field properties of the cloud with optical polarization observations. We performed multi-wavelength spectroscopic observations of different species in order to probe the gas phase properties of the cloud. We identified two distinct sub-regions within the cloud. One of the regions hosts purely atomic gas, while the other is dominated by molecular gas although most of it is CO-dark. The estimated plane-of-the-sky magnetic field strength between the two regions remains constant within uncertainties and lies in the range 20-30 micro Gauss. The total magnetic field strength does not scale with density which implies that gas is compressed along the field lines. We also found that turbulence is sub-Alfvenic. The HI velocity gradients are in general perpendicular to the mean magnetic field orientation, except for the region close to the CO clump where they tend to become parallel. The latter is likely related to gas undergoing gravitational infall. The magnetic field morphology of the target cloud is parallel to the HI column density structure of the cloud in the atomic region, while it tends to become perpendicular to the HI structure in the molecular region.2022A&A...665A..77Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/665/A77CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/284 : The USNO-B1.0 Catalog (Monet+ 2003)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/665/A77https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/665/A77http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/665/A77https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/665/A77https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/665/A77http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/665/A77GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/665/A77/um-robop (Polarization data)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/665/A77/um-robop?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/665/A77/um-robop?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/665/A77/um-robop?GETtext/xml+votable180.050000true142.2193970.12260.005555555555555556Cone search capability for table J/A+A/665/A77/list (List of fits datacubes)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/665/A77/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/665/A77/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/665/A77/list?GETtext/xml+votable180.050000true144.7167270.410360.0055555555555555566/7599 7610-7612 7614 7941 7943 7952-7954https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/665/A77?format=asciidefaultJ/A+A/665/A77/um-robopPolarization datae_qError in q (3)stat.errordoubleuu Stokes parameter (2)phys.polarization.stokesdoublee_uError in u (3)stat.errordoubledistStar distance (4)pcpos.distancedoubleb_distLower star distance limit (4)pcpos.distance;stat.mindoubleB_distUpper star distance limit (4)pcpos.distance;stat.maxdoubleRmagR band magnitude (1)magphot.mag;em.opt.Rfloatqq Stokes parameter (2)phys.polarization.stokesdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintUSNOBUSNO-B1.0 id (1)meta.id;meta.maincharRAJ2000Right Ascension (J2000) (1)degpos.eq.ra;meta.mainDEJ2000Declination (J2000) (1)degpos.eq.dec;meta.mainpDegree of polarization (2)phys.polarizationdoublee_pObservational uncertainty in polarization degree (2)stat.errordoubleevpaElectric vector polarization angle (3)degphys.electFielddoublee_evpaObservational uncertainty in polarization angle (3)degstat.errordoubleJ/A+A/665/A77/listList of fits datacubesNzNumber of slicesmeta.numberintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintbVRADLower value of VRAD intervalm/sphys.veloc;pos.heliocentricdoubleBVRADLower value of VRAD intervalm/sphys.veloc;pos.heliocentricfloatdVRADVRAD resolutionm/sspect.resolutionfloatsizeSize of FITS fileKibytephys.size;meta.fitsintTitleTitle of the FITS filemeta.title;meta.fitscharFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitschar