Early Planet Formation in Embedded Disks (eDisk) XIII: Aligned Disks with Non-Settled Dust Around the Newly Resolved Class 0 Protobinary R CrA IRAS 32

Frankie J. Encalada, Leslie W. Looney, Shigehisa Takakuwa, John J. Tobin, Nagayoshi Ohashi, Jes K. Jørgensen, Zhi-Yun Li, Yuri Aikawa, Yusuke Aso, Patrick M. Koch, Woojin Kwon, Shih-Ping Lai, Chang Won Lee, Zhe-Yu Daniel Lin, Alejandro Santamarıa-Miranda, Itziar de Gregorio-Monsalvo, Nguyen Thi Phuong, Adele Plunkett, Jinshi Sai, Rajeeb Sharma, Hsi-Wei Yen, Ilseung Han

Published 2024-03-21Version 1

Young protostellar binary systems, with expected ages less than $\sim$10$^5$ years, are little modified since birth, providing key clues to binary formation and evolution. We present a first look at the young, Class 0 binary protostellar system R CrA IRAS 32 from the Early Planet Formation in Embedded Disks (eDisk) ALMA large program, which observed the system in the 1.3 mm continuum emission, $^{12}$CO (2-1), $^{13}$CO (2-1), C$^{18}$O (2-1), SO (6$_5$-5$_4$), and nine other molecular lines that trace disk, envelope, shocks, and outflows. With a continuum resolution of $\sim$0.03$^{\prime\prime}$ ($\sim$5 au, at a distance of 150 pc), we characterize the newly discovered binary system with a separation of 207 au, their circumstellar disks, and a circumbinary disk-like structure. The circumstellar disk radii are 26.9$\pm$0.3 and 22.8$\pm$0.3 au for sources A and B, respectively, and their circumstellar disk dust masses are estimated as 22.5$\pm$1.1 and 12.4$\pm$0.6 M$_{\Earth}$. The circumstellar disks and the circumbinary structure have well aligned position angles and inclinations, indicating formation in a smooth, ordered process such as disk fragmentation. In addition, the circumstellar disks have a near/far-side asymmetry in the continuum emission suggesting that the dust has yet to settle into a thin layer near the midplane. Spectral analysis of CO isotopologues reveals outflows that originate from both of the sources and possibly from the circumbinary disk-like structure. Furthermore, we detect Keplerian rotation in the $^{13}$CO isotopologues toward both circumstellar disks and likely Keplerian rotation in the circumbinary structure; the latter suggests that it is probably a circumbinary disk.