The Astrophysical Journal (Jan 2023)

Early Planet Formation in Embedded Disks (eDisk). VII. Keplerian Disk, Disk Substructure, and Accretion Streamers in the Class 0 Protostar IRAS 16544–1604 in CB 68

  • Miyu Kido,
  • Shigehisa Takakuwa,
  • Kazuya Saigo,
  • Nagayoshi Ohashi,
  • John J. Tobin,
  • Jes K. Jørgensen,
  • Yuri Aikawa,
  • Yusuke Aso,
  • Frankie J. Encalada,
  • Christian Flores,
  • Sacha Gavino,
  • Itziar de Gregorio-Monsalvo,
  • Ilseung Han,
  • Shingo Hirano,
  • Patrick M. Koch,
  • Woojin Kwon,
  • Shih-Ping Lai,
  • Chang Won Lee,
  • Jeong-Eun Lee,
  • Zhi-Yun Li,
  • Zhe-Yu Daniel Lin,
  • Leslie W. Looney,
  • Shoji Mori,
  • Suchitra Narayanan,
  • Adele L. Plunkett,
  • Nguyen Thi Phuong,
  • Jinshi Sai (Insa Choi),
  • Alejandro Santamaría-Miranda,
  • Rajeeb Sharma,
  • Patrick D. Sheehan,
  • Travis J. Thieme,
  • Kengo Tomida,
  • Merel L. R. van ’t Hoff,
  • Jonathan P. Williams,
  • Yoshihide Yamato,
  • Hsi-Wei Yen

DOI
https://doi.org/10.3847/1538-4357/acdd7a
Journal volume & issue
Vol. 953, no. 2
p. 190

Abstract

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We present observations of the Class 0 protostar IRAS 16544–1604 in CB 68 from the “Early Planet Formation in Embedded Disks (eDisk)” ALMA Large program. The ALMA observations target continuum and lines at 1.3 mm with an angular resolution of ∼5 au. The continuum image reveals a dusty protostellar disk with a radius of ∼30 au seen close to edge-on and asymmetric structures along both the major and minor axes. While the asymmetry along the minor axis can be interpreted as the effect of the dust flaring, the asymmetry along the major axis comes from a real nonaxisymmetric structure. The C ^18 O image cubes clearly show the gas in the disk that follows a Keplerian rotation pattern around a ∼0.14 M _⊙ central protostar. Furthermore, there are ∼1500 au scale streamer-like features of gas connecting from northeast, north–northwest, and northwest to the disk, as well as the bending outflow as seen in the ^12 CO (2–1) emission. At the apparent landing point of the NE streamer, there is SO (6 _5 –5 _4 ) and SiO (5–4) emission detected. The spatial and velocity structure of the NE streamer can be interpreted as a free-falling gas with a conserved specific angular momentum, and the detection of the SO and SiO emission at the tip of the streamer implies the presence of accretion shocks. Our eDisk observations have unveiled that the Class 0 protostar in CB 68 has a Keplerian-rotating disk with a flaring and nonaxisymmetric structure associated with accretion streamers and outflows.

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