The Keplerian Disk, Envelope, and Streamers Surrounding an Early O-type Protostar in the Sagittarius C Cloud of the Central Molecular Zone

2026/05/05 by Jixiang Weng, Xing Lu, Xing 行 Lu 吕 +27 · 1 voice
Chemistry · Materials Science · Physics and Astronomy · #Accretion (finance) #Accretion disc #Astrophysics and Star Formation Studies #Fullerene Chemistry and Applications #Molecular cloud #Polymer Nanocomposite Synthesis and Irradiation #Protostar #RADIUS #Star formation #Stars #astro-ph.GA

paper · pdf · doi:10.3847/1538-4357/ae6813

arxiv published 2026/05/05 · arxiv updated 2026/05/05 · openalex publication_date 2026/05/28 · openalex created_date 2026/05/29 · openalex updated_date 2026/08/01

Abstract

Abstract Disk-mediated accretion is central to theories of massive star formation, setting the initial conditions for their evolution. Yet observations of Keplerian disks around early O-type protostars remain scarce, as they are often blended into complex surrounding structures. We report Atacama Large Millimeter/submillimeter Array Band 6 observations (300 au resolution) of an accretion disk surrounding a high-mass protostar in the Sagittarius C cloud in the Central Molecular Zone (CMZ) around the Galactic center. We identify spectral lines and analyze the spatial distribution of the emission of the complex organic molecules. We use a dynamical model with an inner Keplerian disk and an outer free-fall envelope to fit the three-dimensional position–position–velocity data of the stacked CH 3 OCHO molecular lines and constrain the mass of the central protostar to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:mn>4</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mtext/> <mml:mspace width="0.1em"/> <mml:mtext/> <mml:mspace width="0.1em"/> </mml:math> . The fitting results additionally show that the disk has a centrifugal radius at about 1300 au. Considering the infall velocity, radius, and mass of the envelope, we estimate the accretion rate from the envelope onto the disk to be ∼7 × 10 −3 M ⊙ yr −1 . We also identify spiral-like structures in the disk that can be described by free-falling streamers. Our results highlight the critical role of accretion disks and streamers in the mass accumulation of early O-type stars in the CMZ.

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Discussions

• The Keplerian disk, envelope, and streamers surrounding an early O-type protostar in the Sagittarius C cloud of the Central Molecular Zone Weng et al. arXiv (ApJ) arxiv.org/abs/2605.03883 [bsky, 0 points, 0 comments]

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