Hot Molecular Circumstellar Disk around Massive Protostar Orion Source I

Abstract

We report new Atacama Large Millimeter/Submillimeter Array (ALMA) observations of a circumstellar disk around Source I in Orion KL, an archetype of massive protostar candidate. We detected two ortho-H${}_2$O lines at 321 GHz ($10_{2,9}$-$9_{3,6}$) and 336 GHz (${\nu }_2=1,5_{2,3}$-$6_{1,6}$) for the first time in Source I. The latter one is in vibrationally excited state at the lower state energy of 2939 K, suggesting an evidence of hot molecular gas close to Source I. The integrated intensity map of the 321 GHz line is elongated along the bipolar outflow while the 336 GHz line map is unresolved with a beam size of 0.4\arcsec. Both of these maps show velocity gradient perpendicular to the bipolar outflow. The velocity centroid map of the 321 GHz line implies spatial and velocity structure similar to that of vibrationally-excited SiO masers tracing the root of the outflow emanating from the disk surface. In contrast, the 336 GHz line is most likely emitted from the disk midplane with a diameter of 0.2\arcsec (84 AU) as traced by a radio continuum emission and a dark lane devoid of the vibrationally-excited SiO maser emission. The observed velocity gradient and the spectral profile of the 336 GHz H${}_2$O line can be reconciled with a model of an edge-on ring-like structure with an enclosed mass of $>$7$M_{\odot }$ and an excitation temperature of $>$3000 K. The present results provide a further evidence of hot and neutral circumstellar disk rotating around Source I with a diameter of $\sim$100 AU scale.

12 pages, 4 figures. Accepted by ApJL

References in corpus (12)

• The distance to the Orion Nebula
• A hot compact dust disk around a massive young stellar object
• Monitoring the Large Proper Motions of Radio Sources in the Orion BN/KL Region
• Imaging the Ionized Disk of the High-Mass Protostar Orion-I
• Dynamical Evidence for a Magnetocentrifugal Wind from a 20 Msun Binary Young Stellar Object
• Submillimeter vibrationally excited water emission from the peculiar red supergiant VY CMa
• ALMA observations of the outflow from the Source I in the Orion-KL region
• Submillimeter Array Observations of 321 GHz Water Maser Emission in Cepheus A
• The first detection of the 232 GHz vibrationally excited H2O maser in Orion KL with ALMA
• Outflow Structure and Velocity Field of Orion Source I: ALMA Imaging of SiO Isotopologue Maser and Thermal Emission
• The Ionized Circumstellar Envelopes of Orion Source I and the Becklin Neugebauer Object
• Keck Adaptive Optics Observations of the Protostellar Disk around Radio Source I in the Orion Kleinmann-Low Nebula

Cited by in corpus (35)

• Disk-Driven Rotating Bipolar Outflow in Orion Source I
• The Physics of Water Masers observable with ALMA and SOFIA: Model Predictions for Evolved Stars
• H2O masers in a jet-driven bowshock: Episodic ejection from a massive young stellar object
• A Keplerian disk around Orion Source I, a ~15 Msun YSO
• Substructures in the Keplerian disc around the O-type (proto)star G17.64+0.16
• Formation and Evolution of Disks around Young Stellar Objects
• Subarcsecond Imaging of the NGC 6334 I(N) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate
• Candidate Water Vapor Lines to Locate the H${}_2$O Snowline through High-Dispersion Spectroscopic Observations II. The Case of a Herbig Ae Star
• ALMA Observations of Orion Source I at 350 and 660 GHz
• A `Water Spout' Maser Jet in S235AB-MIR
• An Asymmetric Keplerian Disk Surrounding the O-type Protostar IRAS16547$-$4247
• Orion Source I's disk is salty
• Salt, Hot Water, and Silicon Compounds Tracing Massive Twin Disks
• Stellar Proper Motions in the Orion Nebula Cluster
• The Orion Protostellar Explosion and Runaway Stars Revisited: Stellar Masses, Disk Retention, and an Outflow from BN
• New Evidence for the Dynamical Decay of a Multiple System in the Orion Kleinmann-Low Nebula
• ALMA Imaging of Millimeter/Submillimeter Continuum Emission in Orion KL
• ATOMIUM: Probing the inner wind of evolved O-rich stars with new, highly excited H${}_2$O and OH lines
• Candidate Water Vapor Lines to Locate the ${\mathrm{H}}_2\mathrm{O}$ Snowline through High-dispersion Spectroscopic Observations. III. Submillimeter ${\mathrm{H}}_2$${}^{16}\mathrm{O}$ and ${\mathrm{H}}_2$${}^{18}\mathrm{O}$ Lines
• Water maser variability in a high-mass YSO outburst -- VERA and ALMA observations of S255 NIRS 3
• Importance of source structure on complex organics emission III. Effect of disks around massive protostars
• VLBI observations of the G25.65+1.05 water maser superburst
• A Face-on Accretion System in High-Mass Star-Formation: Possible Dusty Infall Streams within 100 AU
• Observations of Orion Source I Disk and Outflow Interface
• On the Formation of Runaway Stars BN and x in the Orion Nebula Cluster
• Magnetic Field Structure of Orion Source I
• ALMA Observation of the 658 GHz Vibrationally Excited H${}_2$O Maser in Orion KL Source I
• ALMA band 8 continuum emission from Orion Source I
• ALMA observations and modeling of the rotating outflow in Orion Source I
• Structure of the Source I disk in Orion-KL
• Velocity-resolved hot water emission detected toward HL Tau with the Submillimeter Array
• Extremely high excitation SiO lines in disk-outflow system in Orion Source I
• High spectral resolution observations toward Orion BN at 6 $\mu$m: no evidence for hot water
• An ionized outflow in Orion-KL source I?
• Identifying the Mechanisms of Water Maser Variability During the Accretion Burst in NGC6334I