J/A+A/646/A102ivo://CDS.VizieR/J/A+A/646/A102doi:10.26093/cds/vizier.36460102CDSLabdon A.Kraus S.Davies C.L.Kreplin A.Monnier J.D.,Le Bouquin J.-B.Anugu N.ten Brummelaar T.Setterholm B.Gardner T.,Ennis J.Lanthermann C.Schaefer G.Laws A.2021-07-05T07:39:51Z2021-02-15T07:31:57ZCDS support team

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

cds-question@unistra.frvariable-starsyoung-stellar-objectsinterferometryinfrared-astronomyFU Orionis is the archetypal FUor star, a subclass of young stellar object (YSO) that undergo rapid brightening events, often gaining 4-6 magnitudes on timescales of days. This brightening is often associated with a massive increase in accretion; one of the most ubiquitous processes in astrophysics from planets and stars to super-massive black holes. We present multi-band interferometric observations of the FU Ori circumstellar environment, including the first J-band interferometric observations of a YSO. We investigate the morphology and temperature gradient of the inner-most regions of the accretion disk around FU Orionis. We aim to characterise the heating mechanisms of the disk and comment on potential outburst triggering processes. Methods. Recent upgrades to the MIRC-X instrument at the CHARA array allowed the first dual-band J and H observations of YSOs. Using baselines up to 331m, we present high angular resolution data of a YSO covering the near-infrared bands J, H, and K. The unprecedented spectral range of the data allows us to apply temperature gradient models to the innermost regions of FU Ori. We spatially resolve the innermost astronomical unit of the disk and determine the exponent of the temperature gradient of the inner disk to T{prop.to}r^-0.74+/-0.02^. This agrees with theoretical work that predicts T{prop.to}r^-0.75^ for actively accreting, steady state disks, a value only obtainable through viscous heating within the disk. We find a disk which extends down to the stellar surface at 0.015+/-0.007au where the temperature is found to be 5800+/-700K indicating boundary layer accretion. We find a disk inclined at 32+/-4{deg} with a minor-axis position angle of 34+/-11{deg}.2021A&A...646A.102Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/646/A102CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/646/A102https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/646/A102http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/646/A102https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/646/A102https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/646/A102http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/646/A102GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/646/A102/list (List of OI-FITS files)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/646/A102/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/646/A102/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/646/A102/list?GETtext/xml+votable180.050000true86.34320839.07008330.0055555555555555566/23704https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/646/A102?format=asciiInfrareddefaultJ/A+A/646/A102/listList of OI-FITS filesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Simbad right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Simbad declination (J2000)pos.eq.dec;meta.mainObs.dateObservation datetime.epoch;obsnullablesizeSize of OI-FITS fileKibytephys.size;meta.fileintFileNameName of OI-FITS file, in subdirectory fitsmeta.id;meta.filecharTitleTitle of the OI-FITS filemeta.title;meta.filechar