The ionized warped disk and disk wind of the massive protostar Monoceros R2-IRS2 seen with ALMA

Abstract

Theories of massive star formation predict that massive protostars accrete gas through circumstellar disks. Although several cases have been found already thanks to high-angular resolution interferometry, it remains unknown the internal physical structure of these disks and, in particular, whether they present warps or internal holes as observed in low-mass proto-planetary disks. Here, we report very high angular resolution observations of the H21alpha radio recombination line carried out in Band 9 with the Atacama Large Millimeter/submillimeter Array (beam of 80 mas x 60 mas, or 70 au x 50 au) toward the IRS2 massive young stellar object in the Monoceros R2 star-forming cluster. The H21alpha line shows maser amplification, which allows us to study the kinematics and physical structure of the ionised gas around the massive protostar down to spatial scales of ~1-2 au. Our ALMA images and 3D radiative transfer modelling reveal that the ionized gas around IRS2 is distributed in a Keplerian circumstellar disk and an expanding wind. The H21alpha emission centroids at velocities between -10 and 20 km s-1 deviate from the disk plane, suggesting a warping for the disk. This could be explained by the presence of a secondary object (a stellar companion or a massive planet) within the system. The ionized wind seems to be launched from the disk surface at distances ~11 au from the central star, consistent with magnetically-regulated disk wind models. This suggests a similar wind launching mechanism to that recently found for evolved massive stars such as MWC349A and MWC922.

arXiv commentAccepted for publication in ApJ Letters

References in corpus (25)

• Star formation through gravitational collapse and competitive accretion
• Massive star formation in 100,000 years from turbulent and pressurized molecular clouds
• A disk of dust and molecular gas around a high-mass protostar
• The formation of massive stars: accretion, disks and the development of hypercompact HII regions
• Dynamics of cluster-forming hub-filament systems: The case of the high-mass star-forming complex Monoceros R2
• Substructures in the Keplerian disc around the O-type (proto)star G17.64+0.16
• Outflows and mass accretion in collapsing dense cores with misaligned rotation axis and magnetic field
• Warping a protoplanetary disc with a planet on an inclined orbit
• A Photoevaporating Rotating Disk in the Cepheus A HW2 Star Cluster
• Low Velocity Ionized Winds from Regions Around Young O Stars
• A Hot and Massive Accretion Disk around the High-Mass Protostar IRAS 20126+4104
• Disk structure around the Class I protostar L1489 IRS revealed by ALMA: a warped disk system
• Hydrogen Masers. I: Theory and Prospects
• Near-IR speckle imaging of massive young stellar objects
• SMA Imaging of the Maser Emission from the H30$\alpha$ Radio Recombination Line in MWC349A
• A non-LTE radiative transfer model to study ionized outflows and disks. The case of MWC349A
• Discovery of a parsec-scale bipolar nebula around MWC 349A
• Modeling the accretion disk around the high-mass protostar GGD 27-MM1
• Unveiling the main heating sources in the Cepheus A HW2 region
• A new radio recombination line maser object toward the MonR2 HII region
• Angular Momentum in Disk Wind Revealed in the Young Star MWC349A
• VLBA determination of the distance to nearby star-forming regions VII. Monoceros R2
• Evidence of an evolved nature of MWC 349A
• Origin of the ionized wind in MWC 349A
• A rotating fast bipolar wind and disk system around the B[e]-type star MWC 922

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• FAUST III. Misaligned rotations of the envelope, outflow, and disks in the multiple protostellar system of VLA 1623$-$2417
• ALMA observations of the Extended Green Object G19.01$-$0.03: I. A Keplerian disc in a massive protostellar system
• Massive Protostars in a Protocluster -- A Multi-Scale ALMA View of G35.20-0.74N
• Observing protoplanetary discs with the Square Kilometre Array -- I. Characterising pebble substructure caused by forming planets
• Unveiling the traits of massive young stellar objects through a multi-scale survey
• The ionized heart of a molecular disk. ALMA observations of the hyper-compact HII region G24.78+0.08 A1
• Tying the geometrical traits of massive young stellar objects and their discs to a potential evolutionary sequence using infrared observations
• Clustered Formation of Massive Stars within an Ionized Rotating Disk
• Imaging the jet of MWC 349A with resolved Radio Recombination Line emission from ALMA
• Surveys of clumps, cores, and condensations in Cygnus-X: Searching for Keplerian disks on the scale of 500 au
• The SOFIA Massive (SOMA) Star Formation Q-band Follow-up. II. Hydrogen Recombination Lines Toward High-Mass Protostars