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1. Early Planet Formation in Embedded Disks (eDisk). XIII. Aligned Disks with Nonsettled Dust around the Newly Resolved Class 0 Protobinary R CrA IRAS 32

   https://doi.org/10.3847/1538-4357/ad3442  

   Encalada, Frankie J; Looney, Leslie W; Takakuwa, Shigehisa; Tobin, John J; Ohashi, Nagayoshi; Jørgensen, Jes K; Li, Zhi-Yun; Aikawa, Yuri; Aso, Yusuke; Koch, Patrick M; et al (April 2024, The Astrophysical Journal)

   Abstract Young protostellar binary systems, with expected ages less than ∼10⁵yr, 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 ALMA large program, which observed the system in the 1.3 mm continuum emission,¹²CO (2−1),¹³CO (2−1), C¹⁸O (2−1), SO (6₅−5₄), and nine other molecular lines that trace disks, envelopes, shocks, and outflows. With a continuum resolution of ∼0.″03 (∼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 disklike structure. The circumstellar disk radii are 26.9 ± 0.3 and 22.8 ± 0.3 au for sources A and B, respectively, and their circumstellar disk dust masses are estimated as 22.5 ± 1.1M_⊕and 12.4 ± 0.6M_⊕, respectively. 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 disklike structure. Furthermore, we detect Keplerian rotation in the¹³CO isotopologues toward both circumstellar disks and likely Keplerian rotation in the circumbinary structure; the latter suggests that it is probably a circumbinary disk. 

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2. 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

   https://doi.org/10.3847/1538-4357/acdd7a  

   Kido, Miyu; Takakuwa, Shigehisa; Saigo, Kazuya; Ohashi, Nagayoshi; Tobin, John J; Jørgensen, Jes K; Aikawa, Yuri; Aso, Yusuke; Encalada, Frankie J; Flores, Christian; et al (August 2023, The Astrophysical Journal)

   Abstract 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 C¹⁸O image cubes clearly show the gas in the disk that follows a Keplerian rotation pattern around a ∼0.14M_⊙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 the¹²CO (2–1) emission. At the apparent landing point of the NE streamer, there is SO (6₅–5₄) 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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3. Early Planet Formation in Embedded Disks (eDisk). XXII. Keplerian Disk, Disk Structures, and Jets/Outflows in the Class 0 Protostar IRAS 04166+2706

   https://doi.org/10.3847/1538-4357/adfa92  

   Phuong, Nguyen Thi; Lee, Chang Won; Tobin, John J; Ohashi, Nagayoshi; Jørgensen, Jes K; Takakuwa, Shigehisa; Aikawa, Yuri; Aso, Yusuke; Li, Zhi-Yun; Koch, Patrick M; et al (October 2025, The Astrophysical Journal)

   Abstract We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the Class 0 protostar IRAS 04166+2706, obtained as part of the ALMA Large Program Early Planet Formation in Embedded Disks. These observations were made in the 1.3 mm dust continuum and molecular lines at angular resolutions of $\sim 0\stackrel{″}{.}05$(∼8 au) and $\sim 0\stackrel{″}{.}16$(∼25 au), respectively. The continuum emission shows a disklike structure with a radius of ∼22 au. Kinematical analysis of¹³CO (2–1), C¹⁸O (2–1), H₂CO (3_0,3–2_0,2), CH₃OH (4₂–3₁) emission demonstrates that these molecular lines trace the infalling-rotating envelope and possibly a Keplerian disk, enabling us to estimate the protostar mass to be 0.15M_⊙ < M_⋆ < 0.39M_⊙. The dusty disk is found to exhibit a brightness asymmetry along its minor axis in the continuum emission, probably caused by a flared distribution of the dust and the high optical depth of the dust emission. In addition, the¹²CO (2–1) and SiO (5–4) emissions show knotty and wiggling motions in the jets. Our high-angular-resolution observations revealed the most recent mass ejection events, which have occurred within the last ∼25 yr. 

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4. Early Planet Formation in Embedded Disks (eDisk): XVI. Asymmetric dust disk driving a multicomponent molecular outflow in the young Class 0 protostar GSS30 IRS3

   https://doi.org/10.1051/0004-6361/202449981  

   Santamaría-Miranda, Alejandro; de_Gregorio-Monsalvo, Itziar; Ohashi, Nagayoshi; Tobin, John J; Sai, Jinshi; Jørgensen, Jes K; Aso, Yusuke; Daniel_Lin, Zhe-Yu; Flores, Christian; Kido, Miyu; et al (October 2024, Astronomy & Astrophysics)

   We present the results of the observations made within the ALMA Large Program called Early Planet Formation in Embedded disks of the Class 0 protostar GSS30 IRS3. Our observations included the 1.3 mm continuum with a resolution of 0″.05 (7.8 au) and several molecular species, including¹²CO,¹³CO, C¹⁸O, H₂CO, and c-C₃H₂. The dust continuum analysis unveiled a disk-shaped structure with a major axis of ~200 au. We observed an asymmetry in the minor axis of the continuum emission suggesting that the emission is optically thick and the disk is flared. On the other hand, we identified two prominent bumps along the major axis located at distances of 26 and 50 au from the central protostar. The origin of the bumps remains uncertain and might be an embedded substructure within the disk or the temperature distribution and not the surface density because the continuum emission is optically thick. The¹²CO emission reveals a molecular outflow consisting of three distinct components: a collimated component, an intermediate-velocity component exhibiting an hourglass shape, and a wider angle low-velocity component. We associate these components with the coexistence of a jet and a disk wind. The C¹⁸O emission traces both a circumstellar disk in Keplerian rotation and the infall of the rotating envelope. We measured a stellar dynamical mass of 0.35 ±0.09 M_⊙. 

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5. Early Planet Formation in Embedded Disks (eDisk). VIII. A Small Protostellar Disk around the Extremely Low Mass and Young Class 0 Protostar IRAS 15398–3359

   https://doi.org/10.3847/1538-4357/ad003a  

   Thieme, Travis J; Lai, Shih-Ping; Ohashi, Nagayoshi; Tobin, John J; Jørgensen, Jes K; Insa_Choi, Jinshi Sai; Aso, Yusuke; Williams, Jonathan P; Yamato, Yoshihide; Aikawa, Yuri; et al (November 2023, The Astrophysical Journal)

   Abstract Protostellar disks are an ubiquitous part of the star formation process and the future sites of planet formation. As part of the Early Planet Formation in Embedded Disks large program, we present high angular resolution dust continuum (∼40 mas) and molecular line (∼150 mas) observations of the Class 0 protostar IRAS 15398–3359. The dust continuum is small, compact, and centrally peaked, while more extended dust structures are found in the outflow directions. We perform a 2D Gaussian fitting and find the deconvolved size and 2σradius of the dust disk to be 4.5 × 2.8 au and 3.8 au, respectively. We estimate the gas+dust disk mass assuming optically thin continuum emission to be 0.6M_J–1.8M_J, indicating a very low mass disk. The CO isotopologues trace components of the outflows and inner envelope, while SO traces a compact, rotating disk-like component. Using several rotation curve fittings on the position–velocity diagram of the SO emission, the lower limits of the protostellar mass and gas disk radius are 0.022M_⊙and 31.2 au, respectively, from our Modified 2 single power-law fitting. A conservative upper limit of the protostellar mass is inferred to be 0.1M_⊙. The protostellar mass accretion rate and the specific angular momentum at the protostellar disk edge are found to be in the range of (1.3–6.1) × 10⁻⁶M_⊙yr⁻¹and (1.2–3.8) × 10⁻⁴km s⁻¹pc, respectively, with an age estimated between 0.4 × 10⁴yr and 7.5 × 10⁴yr. At this young age with no clear substructures in the disk, planet formation would likely not yet have started. This study highlights the importance of high-resolution observations and systematic fitting procedures when deriving dynamical properties of deeply embedded Class 0 protostars. 

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