Multi-epoch sub-arcsecond [Fe II] spectroimaging of the DG Tau outflows with NIFS-I. First data epoch

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dc.contributor.authorWhite, Marc
dc.contributor.authorMcGregor, Peter
dc.contributor.authorBicknell, Geoffrey
dc.contributor.authorSalmeron, Raquel
dc.contributor.authorBeck, Tracy
dc.date.accessioned2015-12-13T22:15:54Z
dc.date.issued2014
dc.date.updated2015-12-11T07:21:09Z
dc.description.abstractInvestigating the outflows emanating from young stellar objects (YSOs) on sub-arcsecond scales provides important clues to the nature of the underlying accretion-ejection process occurring near the central protostar. We have investigated the structures and kinematics of the outflows driven by the YSO DG Tauri, using the Near-infrared Integral Field Spectrograph (NIFS) on Gemini North. The blueshifted outflow shows two distinct components in [Fe II] 1.644 μm emission, which are separated using multicomponent line fitting. Jet parameters are calculated for the high-velocity component. A stationary recollimation shock is observed, in agreement with previous X-ray and far-ultraviolet observations. The presence of this shock indicates that the innermost streamlines of the high-velocity component are launched at a very small radius, 0.01-0.15 au, from the central star. The jet accelerates and expands downstream of the recollimation shock; the 'acceleration' is likely a sign of velocity variations in the jet. No evidence of rotation is found, and we compare this non-detection to previous counterclaims. Moving jet knots, likely the result of the jet velocity variations, are observed. One of these knots moves more slowly than previously observed knots, and the knot ejection interval appears to be non-periodic. An intermediate-velocity component surrounds this central jet, and is interpreted as the result of a turbulent mixing layer along the jet boundaries generated by lateral entrainment of material by the high-velocity jet. Lateral entrainment requires the presence of a magnetic field of strength a few mG or less at hundreds of au above the disc surface, which is argued to be a reasonable proposition. In H2 1-0 S(1) 2.1218 μm emission, a wide-angle, intermediate-velocity blueshifted outflow is observed. Both outflows are consistent with being launched by a magnetocentrifugal disc wind, although an X-wind origin for the high-velocity jet cannot be ruled out. The redshifted outflow of DG Tau takes on a bubble-shaped morphology, which will be discussed in a future paper.
dc.identifier.issn0035-8711
dc.identifier.urihttp://hdl.handle.net/1885/70610
dc.publisherBlackwell Publishing Ltd
dc.rightsAuthor/s retain copyrighten_AU
dc.sourceMonthly Notices of the Royal Astronomical Society
dc.titleMulti-epoch sub-arcsecond [Fe II] spectroimaging of the DG Tau outflows with NIFS-I. First data epoch
dc.typeJournal article
dcterms.accessRightsOpen Accessen_AU
local.bibliographicCitation.issue2
local.bibliographicCitation.lastpage1707
local.bibliographicCitation.startpage1681
local.contributor.affiliationWhite, Marc, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationMcGregor, Peter, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationBicknell, Geoffrey, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationSalmeron, Raquel, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationBeck, Tracy L, Space Telescope Science Institute
local.contributor.authoremailu4630950@anu.edu.au
local.contributor.authoruidWhite, Marc, u4630950
local.contributor.authoruidMcGregor, Peter, u8401248
local.contributor.authoruidBicknell, Geoffrey, u8000061
local.contributor.authoruidSalmeron, Raquel, u4372292
local.description.notesImported from ARIES
local.identifier.absfor020100 - ASTRONOMICAL AND SPACE SCIENCES
local.identifier.ariespublicationU3488905xPUB2360
local.identifier.citationvolume441
local.identifier.doi10.1093/mnras/stu654
local.identifier.scopusID2-s2.0-84900526449
local.identifier.thomsonID000336494800058
local.identifier.uidSubmittedByU3488905
local.type.statusPublished Version

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