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dc.contributor.authorPurser, SJDen
dc.contributor.authorAinsworth, REen
dc.contributor.authorRay, TPen
dc.contributor.authorGreen, Daviden
dc.contributor.authorTaylor, AMen
dc.contributor.authorScaife, AMMen
dc.date.accessioned2019-01-15T00:30:17Z
dc.date.available2019-01-15T00:30:17Z
dc.identifier.issn1365-2966
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/287958
dc.description.abstractDG Tau A, a class-II young stellar object (YSO) displays both thermal, and non-thermal, radio emission associated with its bipolar jet. To investigate the nature of this emission, we present sensitive (sigma ~ 2 microJy/beam), Karl G.\ Jansky Very Large Array (VLA) 6 and 10 GHz observations. Over 3.81 yr, no proper motion is observed towards the non-thermal radio knot C, previously thought to be a bowshock. Its quasi-static nature, spatially-resolved variability and offset from the central jet axis supports a scenario whereby it is instead a stationary shock driven into the surrounding medium by the jet. Towards the internal working surface, knot A, we derive an inclination-corrected, absolute velocity of 258 +/- 23 km/s. DG Tau A's receding counterjet displays a spatially-resolved increase in flux density, indicating a variable mass loss event, the first time such an event has been observed in the counterjet. For this ejection, we measure an ionised mass loss rate of (3.7 +/- 1.0) * 10**8 Msun/yr during the event. A contemporaneous ejection in the approaching jet isn't seen, showing it to be an asymmetric process. Finally, using radiative transfer modelling, we find that the extent of the radio emission can only be explained with the presence of shocks, and therefore reionisation, in the flow. Our modelling highlights the need to consider the relative angular size of optically thick, and thin, radio emission from a jet, to the synthesised beam, when deriving its physical conditions from its spectral index.
dc.publisherOxford University Press
dc.titleConstraining the nature of DG Tau A’s thermal and non-thermal radio emissionen
dc.typeArticle
prism.publicationNameMonthly Notices of the Royal Astronomical Societyen
dc.identifier.doi10.17863/CAM.35278
dcterms.dateAccepted2018-09-21en
rioxxterms.versionofrecord10.1093/mnras/sty2649en
rioxxterms.versionAM
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2018-09-21en
dc.contributor.orcidGreen, David [0000-0003-3189-9998]
dc.identifier.eissn1365-2966
rioxxterms.typeJournal Article/Reviewen
cam.issuedOnline2018-12-21en
cam.orpheus.successThu Jan 30 10:52:20 GMT 2020 - The item has an open VoR version.*
rioxxterms.freetoread.startdate2100-01-01


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