Faculty Profiles - TAKAKUWA Shigehisa

Papers - TAKAKUWA Shigehisa

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Takakuwa S., Saigo K., Kido M., Ohashi N., Tobin J.J., Jørgensen J.K., Aikawa Y., Aso Y., Gavino S., Han I., Koch P.M., Kwon W., Lee C.W., Lee J.E., Li Z.Y., Lin Z.Y.D., Looney L.W., Mori S., Sai J., Sharma R., Sheehan P.D., Tomida K., Williams J.P., Yamato Y., Yen H.W. . Early Planet Formation in Embedded Disks (eDisk). XIV. Flared Dust Distribution and Viscous Accretion Heating of the Disk around R CrA IRS 7B-a . Astrophysical Journal964 ( 1 ) 2024.3Reviewed International coauthorship

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal

We performed radiative transfer calculations and observing simulations to reproduce the 1.3 mm dust-continuum and C18O (2–1) images in the Class I protostar R CrA IRS7B-a, observed with the ALMA Large Program “Early Planet Formation in Embedded Disks (eDisk).” We found that a dust disk model passively heated by the central protostar cannot reproduce the observed peak brightness temperature of the 1.3 mm continuum emission (∼195 K), regardless of the assumptions about the dust opacity. Our calculation suggests that viscous accretion heating in the disk is required to reproduce the observed high brightness temperature. The observed intensity profile of the 1.3 mm dust-continuum emission along the disk minor axis is skewed toward the far side of the disk. Our modeling reveals that this asymmetric intensity distribution requires flaring of the dust along the disk vertical direction with the scale height following h/r ∼ r0.3 as a function of radius. These results are in sharp contrast to those of Class II disks, which show geometrically flat dust distributions and lower dust temperatures. From our modeling of the C18O (2–1) emission, the outermost radius of the gas disk is estimated to be ∼80 au, which is larger than that of the dust disk (∼62 au), to reproduce the observed distribution of the C18O (2–1) emission in IRS 7B-a. Our modeling unveils a hot and thick dust disk plus a larger gas disk around one of the eDisk targets, which could be applicable to other protostellar sources in contrast to more evolved sources.

DOI： 10.3847/1538-4357/ad1f57

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 . 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 . The Astrophysical Journal953 ( 2 ) 190 - 190 2023.8Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

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 C<sup>18</sup>O image cubes clearly show the gas in the disk that follows a Keplerian rotation pattern around a ∼0.14 M<sub>⊙</sub> 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 <sup>12</sup>CO (2–1) emission. At the apparent landing point of the NE streamer, there is SO (6<sub>5</sub>–5<sub>4</sub>) 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.

DOI： 10.3847/1538-4357/acdd7a

Other Link： https://iopscience.iop.org/article/10.3847/1538-4357/acdd7a/pdf

Santamaría-Miranda A., De Gregorio-Monsalvo I., Ohashi N., Tobin J.J., Sai J., Jørgensen J.K., Aso Y., Daniel Lin Z.Y., Flores C., Kido M., Koch P.M., Kwon W., Lee C.W., Li Z.Y., Looney L.W., Plunkett A.L., Takakuwa S., R Van't Hoff M.L., Williams J.P., Yen H.W. . Early Planet Formation in Embedded Disks (eDisk): XVI. Asymmetric dust disk driving a multicomponent molecular outflow in the young Class 0 protostar GSS30 IRS3 . Astronomy and Astrophysics690 2024.10

Language：Japanese Publisher：Astronomy and 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, including 12CO, 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. The 12CO 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⊙

DOI： 10.1051/0004-6361/202449981

Gavino S., Jørgensen J.K., Sharma R., Yang Y.L., Li Z.Y., Tobin J.J., Ohashi N., Takakuwa S., Plunkett A.L., Kwon W., de Gregorio-Monsalvo I., Lin Z.Y.D., Santamaría-Miranda A., Aso Y., Sai J., Aikawa Y., Tomida K., Koch P.M., Lee J.E., Lee C.W., Lai S.P., Looney L.W., Narayanan S., Phuong N.T., Thieme T.J., van ’t Hoff M.L.R., Williams J.P., Yen H.W. . Early Planet Formation in Embedded Disks. XI. A High-resolution View Toward the BHR 71 Class 0 Protostellar Wide Binary . Astrophysical Journal974 ( 1 ) 2024.10

Language：Japanese Publisher：Astrophysical Journal

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the binary Class 0 protostellar system BHR 71 IRS1 and IRS2 as part of the Early Planet Formation in Embedded Disks (eDisk) ALMA Large Program. We describe the 12CO (J = 2-1), 13CO (J = 2-1), C18O (J = 2-1), H2CO (J = 32,1-22,0), and SiO (J = 5-4) molecular lines along with the 1.3 mm continuum at high spatial resolution (∼0.″08 or ∼5 au). Dust continuum emission is detected toward BHR 71 IRS1 and IRS2, with a central compact component and extended continuum emission. The compact components are smooth and show no sign of substructures such as spirals, rings, or gaps. However, there is a brightness asymmetry along the minor axis of the presumed disk in IRS1, possibly indicative of an inclined geometrically and optically thick disk-like component. Using a position-velocity diagram analysis of the C18O line, clear Keplerian motions were not detected toward either source. If Keplerian rotationally supported disks are present, they are likely deeply embedded in their envelope. However, we can set upper limits of the central protostellar mass of 0.46 M ⊙ and 0.26 M ⊙ for BHR 71 IRS1 and BHR 71 IRS2, respectively. Outflows traced by 12CO and SiO are detected in both sources. The outflows can be divided into two components, a wide-angle outflow and a jet. In IRS1, the jet exhibits a double helical structure, reflecting the removal of angular momentum from the system. In IRS2, the jet is very collimated and shows a chain of knots, suggesting episodic accretion events.

DOI： 10.3847/1538-4357/ad655e

Yen H.W., Williams J.P., Sai J., Koch P.M., Han I., Jørgensen J.K., Kwon W., Lee C.W., Li Z.Y., Looney L.W., Narang M., Ohashi N., Takakuwa S., Tobin J.J., de Gregorio-Monsalvo I., Lai S.P., Lee J.E., Tomida K. . Early Planet Formation in Embedded Disks (eDisk). XV. Influence of Magnetic Field Morphology in Dense Cores on Sizes of Protostellar Disks . Astrophysical Journal969 ( 2 ) 2024.7Reviewed International coauthorship

Encalada F.J., Looney L.W., Takakuwa S., Tobin J.J., Ohashi N., Jørgensen J.K., Li Z.Y., Aikawa Y., Aso Y., Koch P.M., Kwon W., Lai S.P., Lee C.W., Lin Z.Y.D., Santamaría-Miranda A., de Gregorio-Monsalvo I., Phuong N.T., Plunkett A., Sai J., Sharma R., Yen H.W., Han I. . Early Planet Formation in Embedded Disks (eDisk). XIII. Aligned Disks with Nonsettled Dust around the Newly Resolved Class 0 Protobinary R CrA IRAS 32 . Astrophysical Journal966 ( 1 ) 2024.5Reviewed International coauthorship

Daisuke Takaishi, Yusuke Tsukamoto, Miyu Kido, Shigehisa Takakuwa, Yoshiaki Misugi, Yuki Kudoh, Yasushi Suto . Formation of Unipolar Outflow and Protostellar Rocket Effect in Magnetized Turbulent Molecular Cloud Cores . Astrophysical Journal963 ( 1 ) 2024.3Reviewed

Language：English Publishing type：Research paper (scientific journal)

Observed protostellar outflows exhibit a variety of asymmetrical features, including remarkable unipolar outflows and bending outflows. Revealing the formation and early evolution of such asymmetrical protostellar outflows, especially the unipolar outflows, is essential for a better understanding of the star and planet formation because they can dramatically change the mass accretion and angular momentum transport to the protostars and protoplanetary disks. Here we perform three-dimensional nonideal magnetohydrodynamics simulations to investigate the formation and early evolution of the asymmetrical protostellar outflows in magnetized turbulent isolated molecular cloud cores. We find, for the first time to our knowledge, that the unipolar outflow forms even in the single low-mass protostellar system. The results show that the unipolar outflow is driven in the weakly magnetized cloud cores with the dimensionless mass-to-flux ratios of μ = 8 and 16. Furthermore, we find the protostellar rocket effect of the unipolar outflow, which is similar to the launch and propulsion of a rocket. The unipolar outflow ejects the protostellar system from the central dense region to the outer region of the parent cloud core, and the ram pressure caused by its ejection suppresses the driving of additional new outflows. In contrast, the bending bipolar outflow is driven in the moderately magnetized cloud core with μ = 4. The ratio of the magnetic to turbulent energies of a parent cloud core may play a key role in the formation of asymmetrical protostellar outflows.

DOI： 10.3847/1538-4357/ad187a

Thieme T.J., Lai S.P., Ohashi N., Tobin J.J., Jørgensen J.K., Insa Choi J.S., Aso Y., Williams J.P., Yamato Y., Aikawa Y., de Gregorio-Monsalvo I., Han I., Kwon W., Lee C.W., Lee J.E., Li Z.Y., Lin Z.Y.D., Looney L.W., Narayanan S., Phuong N.T., Plunkett A.L., Santamaría-Miranda A., Sharma R., Takakuwa S., Yen H.W. . 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 . Astrophysical Journal958 ( 1 ) 2023.11Reviewed International coauthorship

Flores C., Ohashi N., Tobin J.J., Jørgensen J.K., Takakuwa S., Li Z.Y., Lin Z.Y.D., van ’t Hoff M.L.R., Plunkett A.L., Yamato Y., Sai (Insa Choi) J., Koch P.M., Yen H.W., Aikawa Y., Aso Y., de Gregorio-Monsalvo I., Kido M., Kwon W., Lee J.E., Lee C.W., Looney L.W., Santamaría-Miranda A., Sharma R., Thieme T.J., Williams J.P., Han I., Narayanan S., Lai S.P. . Early Planet Formation in Embedded Disks (eDisk). XII. Accretion Streamers, Protoplanetary Disk, and Outflow in the Class I Source Oph IRS 63 . Astrophysical Journal958 ( 1 ) 2023.11Reviewed International coauthorship

Narayanan S., Williams J.P., Tobin J.J., Jørgensen J.K., Ohashi N., Lin Z.Y.D., van’t Hoff M.L.R., Li Z.Y., Plunkett A.L., Looney L.W., Takakuwa S., Yen H.W., Aso Y., Flores C., Lee J.E., Lai S.P., Kwon W., de Gregorio-Monsalvo I., Sharma R., Lee C.W. . Early Planet Formation in Embedded Disks (eDisk). X. Compact Disks, Extended Infall, and a Fossil Outburst in the Class I Oph IRS43 Binary . Astrophysical Journal958 ( 1 ) 2023.11Reviewed International coauthorship

Sharma R., Jørgensen J.K., Gavino S., Ohashi N., Tobin J.J., Lin Z.Y.D., Li Z.Y., Takakuwa S., Lee C.W., Sai (insa Choi) J., Kwon W., De Gregorio-Monsalvo I., Santamaria-Miranda A., Yen H.W., Aikawa Y., Aso Y., Lai S.P., Lee J.E., Looney L.W., Phuong N.T., Thieme T.J., Williams J.P. . Early Planet Formation in Embedded Disks (eDisk). IX. High-resolution ALMA Observations of the Class 0 Protostar R CrA IRS5N and Its Surroundings . Astrophysical Journal954 ( 1 ) 2023.9Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal

We present high-resolution high-sensitivity observations of the Class 0 protostar RCrA IRS5N as part of the Atacama Large Milimeter/submilimeter Array large program Early Planet Formation in Embedded Disks. The 1.3 mm continuum emission reveals a flattened continuum structure around IRS5N, consistent with a protostellar disk in the early phases of evolution. The continuum emission appears smooth and shows no substructures. However, a brightness asymmetry is observed along the minor axis of the disk, suggesting that the disk is optically and geometrically thick. We estimate the disk mass to be between 0.007 and 0.02 M ⊙. Furthermore, molecular emission has been detected from various species, including C18O (2-1), 12CO (2-1), 13CO (2-1), and H2CO (30,3 - 20,2, 32,1 - 22,0, and 32,2 - 22,1). By conducting a position-velocity analysis of the C18O (2-1) emission, we find that the disk of IRS5N exhibits characteristics consistent with Keplerian rotation around a central protostar with a mass of approximately 0.3 M ⊙. Additionally, we observe dust continuum emission from the nearby binary source IRS5a/b. The emission in 12CO toward IRS5a/b seems to emanate from IRS5b and flow into IRS5a, suggesting material transport between their mutual orbits. The lack of a detected outflow and large-scale negatives in 12CO observed toward IRS5N suggests that much of the flux from IRS5N is being resolved out. Using a 1D radiative transfer model, we infer the mass of the envelope surrounding IRS5N to be 1/41.2 M ⊙. Due to this substantial surrounding envelope, the central IRS5N protostar is expected to be significantly more massive in the future.

DOI： 10.3847/1538-4357/ace35c

Aso Y., Kwon W., Ohashi N., Jørgensen J.K., Tobin J.J., Aikawa Y., de Gregorio-Monsalvo I., Han I., Kido M., Koch P.M., Lai S.P., Lee C.W., Lee J.E., Li Z.Y., Lin Z.Y.D., Looney L.W., Narayanan S., Phuong N.T., Insa Choi J.S., Saigo K., Santamaría-Miranda A., Sharma R., Takakuwa S., Thieme T.J., Tomida K., Williams J.P., Yen H.W. . Early Planet Formation in Embedded Disks (eDisk). VI. Kinematic Structures around the Very-low-mass Protostar IRAS 16253-2429 . Astrophysical Journal954 ( 1 ) 2023.9Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal

Precise estimates of protostellar masses are crucial to characterize the formation of stars of low masses down to brown dwarfs (BDs; M * < 0.08 M ☉). The most accurate estimation of protostellar mass uses the Keplerian rotation in the circumstellar disk around the protostar. To apply the Keplerian rotation method to a protostar at the low-mass end, we have observed the Class 0 protostar IRAS 16253-2429 using the Atacama Large Millimeter/submillimeter Array (ALMA) in the 1.3 mm continuum at an angular resolution of 0.″07 (10 au), and in the 12CO, C18O, 13CO (J = 2-1), and SO (J N = 65−54) molecular lines, as part of the ALMA Large Program Early Planet Formation in Embedded Disks project. The continuum emission traces a nonaxisymmetric, disk-like structure perpendicular to the associated 12CO outflow. The position-velocity (PV) diagrams in the C18O and 13CO lines can be interpreted as infalling and rotating motions. In contrast, the PV diagram along the major axis of the disk-like structure in the 12CO line allows us to identify Keplerian rotation. The central stellar mass and the disk radius are estimated to be ∼0.12-0.17 M ☉ and ∼13-19 au, respectively. The SO line suggests the existence of an accretion shock at a ring (r ∼ 28 au) surrounding the disk and a streamer from the eastern side of the envelope. IRAS 16253-2429 is not a proto-BD but has a central stellar mass close to the BD mass regime, and our results provide a typical picture of such very-low-mass protostars.

DOI： 10.3847/1538-4357/ace624

Sai J., Yen H.W., Ohashi N., Tobin J.J., Jørgensen J.K., Takakuwa S., Saigo K., Aso Y., Lin Z.Y.D., Koch P.M., Aikawa Y., Flores C., De Gregorio-Monsalvo I., Han I., Kido M., Kwon W., Lai S.P., Lee C.W., Lee J.E., Li Z.Y., Looney L.W., Mori S., Phuong N.T., Santamaria-Miranda A., Sharma R., Thieme T.J., Tomida K., Williams J.P. . Early Planet Formation in Embedded Disks (eDisk). V. Possible Annular Substructure in a Circumstellar Disk in the Ced110 IRS4 System . Astrophysical Journal954 ( 1 ) 2023.9Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal

We have observed the Class 0/I protostellar system Ced110 IRS4 at an angular resolution of 0.″05 ( 1/410 au) as part of the Atacama Large Millimeter/submillimeter Array large program, Early Planet Formation in Embedded Disks. The 1.3 mm dust continuum emission reveals that Ced110 IRS4 is a binary system with a projected separation of 1/4250 au. The continuum emissions associated with the main source and its companion, named Ced110 IRS4A and IRS4B, respectively, exhibit disk-like shapes and likely arise from dust disks around the protostars. The continuum emission of Ced110 IRS4A has a radius of 1/4110 au ( 1/40.″6) and shows bumps along its major axis with an asymmetry. The bumps can be interpreted as a shallow, ring-like structure at a radius of 1/440 au ( 1/40.″2) in the continuum emission, as demonstrated from two-dimensional intensity distribution models. A rotation curve analysis on the C18O and 13CO J = 2-1 lines reveals the presence of a Keplerian disk within a radius of 120 au around Ced110 IRS4A, which supports the interpretation that the dust continuum emission arises from a disk. The ring-like structure in the dust continuum emission might indicate a possible annular substructure in the surface density of the embedded disk, although the possibility that it is an apparent structure due to the optically thick continuum emission cannot be ruled out.

DOI： 10.3847/1538-4357/ace52d

Kotomi Taniguchi, Liton Majumdar, Paola Caselli, Shigehisa Takakuwa, Tien-Hao Hsieh, Masao Saito, Zhi-Yun Li, Kazuhito Dobashi, Tomomi Shimoikura, Fumitaka Nakamura, Jonathan C. Tan, Eric Herbst . Chemical Differentiation around Five Massive Protostars Revealed by ALMA: Carbon-chain Species and Oxygen/Nitrogen-bearing Complex Organic Molecules . The Astrophysical Journal Supplement Series267 ( 1 ) 4 - 4 2023.7Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

Abstract

We present Atacama Large Millimeter/submillimeter Array Band 3 data toward five massive young stellar objects (MYSOs), and investigate relationships between unsaturated carbon-chain species and saturated complex organic molecules (COMs). An HC<sub>5</sub>N (J = 35–34) line has been detected from three MYSOs, where nitrogen (N)-bearing COMs (CH<sub>2</sub>CHCN and CH<sub>3</sub>CH<sub>2</sub>CN) have been detected. The HC<sub>5</sub>N spatial distributions show compact features and match with a methanol (CH<sub>3</sub>OH) line with an upper-state energy around 300 K, which should trace hot cores. The hot regions are more extended around the MYSOs where N-bearing COMs and HC<sub>5</sub>N have been detected compared to two MYSOs without these molecular lines, while there are no clear differences in the bolometric luminosity and temperature. We run chemical simulations of hot-core models with a warm-up stage, and compare with the observational results. The observed abundances of HC<sub>5</sub>N and COMs show good agreements with the model at the hot-core stage with temperatures above 160 K. These results indicate that carbon-chain chemistry around the MYSOs cannot be reproduced by warm carbon-chain chemistry, and a new type of carbon-chain chemistry occurs in hot regions around MYSOs.

DOI： 10.3847/1538-4365/acd110

Other Link： https://iopscience.iop.org/article/10.3847/1538-4365/acd110/pdf

Lin Z.Y.D., Li Z.Y., Tobin J.J., Ohashi N., Jørgensen J.K., Looney L.W., Aso Y., Takakuwa S., Aikawa Y., van’t Hoff M.L.R., de Gregorio-Monsalvo I., Encalada F.J., Flores C., Gavino S., Han I., Kido M., Koch P.M., Kwon W., Lai S.P., Lee C.W., Lee J.E., Phuong N.T., Sai (Insa Choi) J., Sharma R., Sheehan P., Thieme T.J., Williams J.P., Yamato Y., Yen H.W. . Early Planet Formation in Embedded Disks (eDisk). II. Limited Dust Settling and Prominent Snow Surfaces in the Edge-on Class I Disk IRAS 04302+2247 . Astrophysical Journal951 ( 1 ) 2023.7Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal

While dust disks around optically visible, Class II protostars are found to be vertically thin, when and how dust settles to the midplane are unclear. As part of the Atacama Large Millimeter/submillimeter Array large program, Early Planet Formation in Embedded Disks, we analyze the edge-on, embedded, Class I protostar IRAS 04302+2247, also nicknamed the “Butterfly Star.” With a resolution of 0.″05 (8 au), the 1.3 mm continuum shows an asymmetry along the minor axis that is evidence of an optically thick and geometrically thick disk viewed nearly edge-on. There is no evidence of rings and gaps, which could be due to the lack of radial substructure or the highly inclined and optically thick view. With 0.″1 (16 au) resolution, we resolve the 2D snow surfaces, i.e., the boundary region between freeze-out and sublimation, for 12CO J = 2-1, 13CO J = 2-1, C18O J = 2-1, H 2CO J = 30,3-20,2, and SO J = 65-54, and constrain the CO midplane snow line to ∼130 au. We find Keplerian rotation around a protostar of 1.6 ± 0.4 M ⊙ using C18O. Through forward ray-tracing using RADMC-3D, we find that the dust scale height is ∼6 au at a radius of 100 au from the central star and is comparable to the gas pressure scale height. The results suggest that the dust of this Class I source has yet to vertically settle significantly.

DOI： 10.3847/1538-4357/acd5c9

van ’t Hoff M.L.R., Tobin J.J., Li Z.Y., Ohashi N., Jørgensen J.K., Lin Z.Y.D., Aikawa Y., Aso Y., de Gregorio-Monsalvo I., Gavino S., Han I., Koch P.M., Kwon W., Lee C.W., Lee J.E., Looney L.W., Narayanan S., Plunkett A., Insa Choi J.S., Santamaría-Miranda A., Sharma R., Sheehan P.D., Takakuwa S., Thieme T.J., Williams J.P., Lai S.P., Phuong N.T., Yen H.W. . Early Planet Formation in Embedded Disks (eDisk). III. A First High-resolution View of Submillimeter Continuum and Molecular Line Emission toward the Class 0 Protostar L1527 IRS . Astrophysical Journal951 ( 1 ) 2023.7Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal

Studying the physical and chemical conditions of young embedded disks is crucial to constrain the initial conditions for planet formation. Here we present Atacama Large Millimeter/submillimeter Array observations of dust continuum at ∼0.″06 (8 au) resolution and molecular line emission at ∼0.″17 (24 au) resolution toward the Class 0 protostar L1527 IRS from the Large Program eDisk (Early Planet Formation in Embedded Disks). The continuum emission is smooth without substructures but asymmetric along both the major and minor axes of the disk as previously observed. The detected lines of 12CO, 13CO, C18O, H2CO, c-C3H2, SO, SiO, and DCN trace different components of the protostellar system, with a disk wind potentially visible in 12CO. The 13CO brightness temperature and the H2CO line ratio confirm that the disk is too warm for CO freezeout, with the snowline located at ∼350 au in the envelope. Both molecules show potential evidence of a temperature increase around the disk-envelope interface. SO seems to originate predominantly in UV-irradiated regions such as the disk surface and the outflow cavity walls rather than at the disk-envelope interface as previously suggested. Finally, the continuum asymmetry along the minor axis is consistent with the inclination derived from the large-scale (100″ or 14,000 au) outflow, but opposite to that based on the molecular jet and envelope emission, suggesting a misalignment in the system. Overall, these results highlight the importance of observing multiple molecular species in multiple transitions to characterize the physical and chemical environment of young disks.

DOI： 10.3847/1538-4357/accf87

Nagayoshi Ohashi, John J. Tobin, Jes K. Jørgensen, Shigehisa Takakuwa, Patrick Sheehan, Yuri Aikawa, Zhi-Yun Li, Leslie W. Looney, Jonathan P. Williams, Yusuke Aso, Rajeeb Sharma, Jinshi Sai (Insa Choi), Yoshihide Yamato, Jeong-Eun Lee, Kengo Tomida, Hsi-Wei Yen, Frankie J. Encalada, Christian Flores, Sacha Gavino, Miyu Kido, Ilseung Han, Zhe-Yu Daniel Lin, Suchitra Narayanan, Nguyen Thi Phuong, Alejandro Santamaría-Miranda, Travis J. Thieme, Merel L. R. van ’t Hoff, Itziar de Gregorio-Monsalvo, Patrick M. Koch, Woojin Kwon, Shih-Ping Lai, Chang Won Lee, Adele Plunkett, Kazuya Saigo, Shingo Hirano, Ka Ho Lam, Shoji Mori . Early Planet Formation in Embedded Disks (eDisk). I. Overview of the Program and First Results . The Astrophysical Journal951 ( 1 ) 8 - 8 2023.6Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

Abstract

We present an overview of the Large Program, “Early Planet Formation in Embedded Disks (eDisk),” conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The ubiquitous detections of substructures, particularly rings and gaps, in protoplanetary disks around T Tauri stars raise the possibility that at least some planet formation may have already started during the embedded stages of star formation. In order to address exactly how and when planet formation is initiated, the program focuses on searching for substructures in disks around 12 Class 0 and 7 Class I protostars in nearby (<200 pc) star-forming regions through 1.3 mm continuum observations at a resolution of ∼7 au (0.″04). The initial results show that the continuum emission, mostly arising from dust disks around the sample protostars, has relatively few distinctive substructures, such as rings and spirals, in marked contrast to Class II disks. The dramatic difference may suggest that substructures quickly develop in disks when the systems evolve from protostars to Class II sources, or alternatively that high optical depth of the continuum emission could obscure internal structures. Kinematic information obtained through CO isotopologue lines and other lines reveals the presence of Keplerian disks around protostars, providing us with crucial physical parameters, in particular, the dynamical mass of the central protostars. We describe the background of the eDisk program, the sample selection and their ALMA observations, and the data reduction, and we also highlight representative first-look results.

DOI： 10.3847/1538-4357/acd384

Other Link： https://iopscience.iop.org/article/10.3847/1538-4357/acd384/pdf

Yoshihide Yamato, Yuri Aikawa, Nagayoshi Ohashi, John J. Tobin, Jes K. Jørgensen, Shigehisa Takakuwa, Yusuke Aso, Jinshi Sai (Insa Choi), Christian Flores, Itziar de Gregorio-Monsalvo, Shingo Hirano, Ilseung Han, Miyu Kido, 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, Nguyen Thi Phuong, Kazuya Saigo, Alejandro Santamaría-Miranda, Rajeeb Sharma, Travis J. Thieme, Kengo Tomida, Merel L. R. van ’t Hoff, Hsi-Wei Yen . Early Planet Formation in Embedded Disks (eDisk). IV. The Ringed and Warped Structure of the Disk around the Class I Protostar L1489 IRS . The Astrophysical Journal951 ( 1 ) 11 - 11 2023.6Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

Abstract

Constraining the physical and chemical structure of young embedded disks is crucial for understanding the earliest stages of planet formation. As part of the Early Planet Formation in Embedded Disks Atacama Large Millimeter/submillimeter Array Large Program, we present high spatial resolution (∼0.″1 or ∼15 au) observations of the 1.3 mm continuum and <sup>13</sup>CO J = 2–1, C<sup>18</sup>O J = 2–1, and SO J<sub>N</sub> = 6<sub>5</sub>–5<sub>4</sub> molecular lines toward the disk around the Class I protostar L1489 IRS. The continuum emission shows a ring-like structure at 56 au from the central protostar and tenuous, optically thin emission extending beyond ∼300 au. The <sup>13</sup>CO emission traces the warm disk surface, while the C<sup>18</sup>O emission originates from near the disk midplane. The coincidence of the radial emission peak of C<sup>18</sup>O with the dust ring may indicate a gap-ring structure in the gaseous disk as well. The SO emission shows a highly complex distribution, including a compact, prominent component at ≲30 au, which is likely to originate from thermally sublimated SO molecules. The compact SO emission also shows a velocity gradient along a direction tilted slightly (∼15°) with respect to the major axis of the dust disk, which we interpret as an inner warped disk in addition to the warp around ∼200 au suggested by previous work. These warped structures may be formed by a planet or companion with an inclined orbit, or by a gradual change in the angular momentum axis during gas infall.

DOI： 10.3847/1538-4357/accd71

Other Link： https://iopscience.iop.org/article/10.3847/1538-4357/accd71/pdf

Tetsu Kitayama, Shutaro Ueda, Nobuhiro Okabe, Takuya Akahori, Matt Hilton, John P. Hughes, Yuto Ichinohe, Kotaro Kohno, Eiichiro Komatsu, Yen Ting Lin, Hironao Miyatake, Masamune Oguri, Cristóbal Sifón, Shigehisa Takakuwa, Motokazu Takizawa, Takahiro Tsutsumi, Joshiwa van Marrewijk, Edward J. Wollack . Galaxy clusters at z ∼ 1 imaged by ALMA with the Sunyaev–Zel’dovich effect . Publications of the Astronomical Society of Japan75 ( 2 ) 311 - 337 2023.4Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal)

We present high angular resolution measurements of the thermal Sunyaev–Zel’dovich effect (SZE) toward two galaxy clusters, RCS J2319+0038 at z = 0.9 and HSC J0947−0119 at z = 1.1, by the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 3. They are supplemented with available Chandra X-ray data, optical data taken by Hyper Suprime-Cam on Subaru, and millimeter-wave SZE data from the Atacama Cosmology Telescope. Taking into account departures from spherical symmetry, we have reconstructed non-parametrically the inner pressure profile of two clusters as well as electron temperature and density profiles for RCS J2319+0038. This is one of the first such measurements for an individual cluster at z ≳ 0.9. We find that the inner pressure profile of both clusters is much shallower than that of local cool-core clusters. Our results consistently suggest that RCS J2319+0038 hosts a weak cool core, where radiative cooling is less significant than in local cool cores. On the other hand, HSC J0947−0119 exhibits an even shallower pressure profile than RCS J2319+0038 and is more likely to be a non-cool-core cluster. The SZE centroid position is offset by more than 140 h−170 kpc from the peaks of galaxy distribution in HSC J0947−0119, suggesting a stronger influence of mergers in this cluster. We conclude that these distant clusters are at a very early stage of developing the cool cores typically found in clusters at lower redshifts.

DOI： 10.1093/pasj/psac110

Hsi-Wei Yen, Patrick M. Koch, Chin-Fei Lee, Naomi Hirano, Nagayoshi Ohashi, Jinshi Sai (Insa Choi), Shigehisa Takakuwa, Ya-Wen Tang, Ken’ichi Tatematsu, Bo Zhao . Increasing Mass-to-flux Ratio from the Dense Core to the Protostellar Envelope around the Class 0 Protostar HH 211 . The Astrophysical Journal942 ( 1 ) 32 - 32 2023.1Reviewed International coauthorship

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

Abstract

To study the transportation of magnetic flux from large to small scales in protostellar sources, we analyzed the Nobeyama 45 m N<sub>2</sub>H<sup>+</sup> (1–0), JCMT 850 μm polarization, and Atacama Large Millimeter/submillimeter Array (ALMA) C<sup>18</sup>O (2–1) and 1.3 and 0.8 mm (polarized) continuum data of the Class 0 protostar HH 211. The magnetic field strength in the dense core on a 0.1 pc scale was estimated with the single-dish line and polarization data using the Davis–Chandrasekhar–Fermi method, and that in the protostellar envelope on a 600 au scale was estimated from the force balance between the gravity and magnetic field tension by analyzing the gas kinematics and magnetic field structures with the ALMA data. Our analysis suggests that from 0.1 pc–600 au scales, the magnetic field strength increases from 40–107 μG to 0.3–1.2 mG with a scaling relation between the magnetic field strength and density of B ∝ ρ <sup>0.36±0.08</sup>, and the mass-to-flux ratio increases from 1.2–3.7 to 9.1–32.3. The increase in the mass-to-flux ratio could suggest that the magnetic field is partially decoupled from the neutral matter between 0.1 pc and 600 au scales, and hint at efficient ambipolar diffusion in the infalling protostellar envelope in HH 211, which is the dominant nonideal magnetohydrodynamic effect considering the density on these scales. Thus, our results could support the scenario of efficient ambipolar diffusion enabling the formation of the 20 au Keplerian disk in HH 211.

DOI： 10.3847/1538-4357/aca47f

Other Link： https://iopscience.iop.org/article/10.3847/1538-4357/aca47f/pdf

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