The Keplerian disk, envelope, and streamers surrounding an early O-type protostar in the Sagittarius C cloud of the Central Molecular Zone

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Main Authors: Weng, Jixiang, Lu, Xing, Cheng, Yu, Deng, Hongping, Mai, Xiaofeng, Zhang, Suinan, Battersby, Cara, Ginsburg, Adam, Mills, Elisabeth A. C., Zhang, Yichen, Liu, Tie, Pillai, Thushara, Tang, Xindi, Olguin, Fernando, Liu, Hauyu Baobab, Zhang, Qizhou, Li, Shanghuo, Li, Guang-Xing, Sanhueza, Patricio, Jiao, Yunfan, Gu, Qilao, Smith, Kai, Zhang, YanKun, Lyu, Tianning, Shen, Zhiqiang
Format: Preprint
Published: 2026
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author Weng, Jixiang
Lu, Xing
Cheng, Yu
Deng, Hongping
Mai, Xiaofeng
Zhang, Suinan
Battersby, Cara
Ginsburg, Adam
Mills, Elisabeth A. C.
Zhang, Yichen
Liu, Tie
Pillai, Thushara
Tang, Xindi
Olguin, Fernando
Liu, Hauyu Baobab
Zhang, Qizhou
Li, Shanghuo
Li, Guang-Xing
Sanhueza, Patricio
Jiao, Yunfan
Gu, Qilao
Smith, Kai
Zhang, YanKun
Lyu, Tianning
Shen, Zhiqiang
author_facet Weng, Jixiang
Lu, Xing
Cheng, Yu
Deng, Hongping
Mai, Xiaofeng
Zhang, Suinan
Battersby, Cara
Ginsburg, Adam
Mills, Elisabeth A. C.
Zhang, Yichen
Liu, Tie
Pillai, Thushara
Tang, Xindi
Olguin, Fernando
Liu, Hauyu Baobab
Zhang, Qizhou
Li, Shanghuo
Li, Guang-Xing
Sanhueza, Patricio
Jiao, Yunfan
Gu, Qilao
Smith, Kai
Zhang, YanKun
Lyu, Tianning
Shen, Zhiqiang
contents 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 ALMA Band 6 observations (300 au resolution) of an accretion disk surrounding a high-mass protostar in the Sagittarius C (Sgr 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 $\sim40^{+2}_{-3} M_{\odot}$. 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 $\sim7\times 10^{-3}\ M_{\odot}\,\mathrm{yr^{-1}}$. 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.
format Preprint
id arxiv_https___arxiv_org_abs_2605_03883
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Keplerian disk, envelope, and streamers surrounding an early O-type protostar in the Sagittarius C cloud of the Central Molecular Zone
Weng, Jixiang
Lu, Xing
Cheng, Yu
Deng, Hongping
Mai, Xiaofeng
Zhang, Suinan
Battersby, Cara
Ginsburg, Adam
Mills, Elisabeth A. C.
Zhang, Yichen
Liu, Tie
Pillai, Thushara
Tang, Xindi
Olguin, Fernando
Liu, Hauyu Baobab
Zhang, Qizhou
Li, Shanghuo
Li, Guang-Xing
Sanhueza, Patricio
Jiao, Yunfan
Gu, Qilao
Smith, Kai
Zhang, YanKun
Lyu, Tianning
Shen, Zhiqiang
Astrophysics of Galaxies
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 ALMA Band 6 observations (300 au resolution) of an accretion disk surrounding a high-mass protostar in the Sagittarius C (Sgr 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 $\sim40^{+2}_{-3} M_{\odot}$. 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 $\sim7\times 10^{-3}\ M_{\odot}\,\mathrm{yr^{-1}}$. 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.
title The Keplerian disk, envelope, and streamers surrounding an early O-type protostar in the Sagittarius C cloud of the Central Molecular Zone
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2605.03883