Faculty Profiles - INUTSUKA, Shu-ichiro

On Secular Gravitational Instability in Vertically Stratified Disks Open Access

Tominaga, RT; Inutsuka, S; Takahashi, SZ

ASTROPHYSICAL JOURNAL Vol. 953 ( 1 ) 2023.8

Publisher：Astrophysical Journal

Secular gravitational instability (GI) is one promising mechanism for explaining planetesimal formation. Previous studies of secular GI utilized a razor-thin disk model and derived the growth condition in terms of vertically integrated physical values such as dust-to-gas surface density ratio. However, in weakly turbulent disks where secular GI can operate, a dust disk can be orders of magnitude thinner than a gas disk, and analyses treating the vertical structures are necessary to clarify the interplay of the midplane dust motion and the upper gas motion. In this work, we perform vertically global linear analyses of secular GI with a vertical domain size of a few gas scale heights. We find that dust grains accumulate radially around the midplane while gas circulates over the whole vertical region. We obtain well-converged growth rates when the outer gas boundary is above two gas scale heights. The growth rates are underestimated if we assume the upper gas to be steady and regard it just as the source of external pressure to the dusty lower layer. Therefore, treating the upper gas motion is important even when the dust disk is much thinner than the gas disk. Conducting a parameter survey, we represent the growth condition in terms of the Toomre Q value for dust and dust-to-gas surface density ratio. The critical dust disk mass for secular GI is ∼10−4 M <inf>*</inf> for a dust-to-gas surface density ratio of 0.01, a Stokes number of 0.1, and a radial dust diffusivity of 10−4 c <inf>s</inf> H, where c <inf>s</inf> is the gas sound speed, and H is the gas scale height.

DOI： 10.3847/1538-4357/ace043

Triple Spiral Arms of a Triple Protostar System Imaged in Molecular Lines Reviewed International coauthorship International journal Open Access

Lee, JE; Matsumoto, T; Kim, HJ; Lee, S; Harsono, D; Bae, J; Evans, J II; Inutsuka, SI; Choi, M; Tatematsu, K; Lee, JJ; Jaffe, D

ASTROPHYSICAL JOURNAL Vol. 953 ( 1 ) 2023.8

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

Most stars form in multiple-star systems. For a better understanding of their formation processes, it is important to resolve the individual protostellar components and the surrounding envelope and disk material at the earliest possible formation epoch, because the formation history can be lost in a few orbital timescales. Here we present Atacama Large Millimeter/submillimeter Array observational results of a young multiple protostellar system, IRAS 04239+2436, where three well-developed large spiral arms were detected in the shocked SO emission. Along the most conspicuous arm, the accretion streamer was also detected in the SO<inf>2</inf> emission. The observational results are complemented by numerical magnetohydrodynamic simulations, where those large arms only appear in magnetically weakened clouds. Numerical simulations also suggest that the large triple spiral arms are the result of gravitational interactions between compact triple protostars and the turbulent infalling envelope.

DOI： 10.3847/1538-4357/acdd5b

Efficient radial migration by giant molecular clouds in the first several hundred Myr after the stellar birth Open Access

The JCMT BISTRO Survey: Studying the Complex Magnetic Field of L43 Open Access

Karoly, J; Ward-Thompson, D; Pattle, K; Berry, D; Whitworth, A; Kirk, J; Bastien, P; Ching, TC; Coudé, S; Hwang, J; Kwon, W; Soam, A; Wang, JW; Hasegawa, T; Lai, SP; Qiu, KP; Arzoumanian, D; Bourke, TL; Byun, DY; Chen, HRV; Chen, WP; Chen, M; Chen, ZW; Cho, J; Choi, M; Choi, Y; Choi, Y; Chrysostomou, A; Chung, EJ; Dai, S; Debattista, V; Di Francesco, J; Diep, PN; Doi, Y; Duan, HY; Duan, Y; Eswaraiah, C; Fanciullo, L; Fiege, J; Fissel, LM; Franzmann, E; Friberg, P; Friesen, R; Fuller, G; Furuya, R; Gledhill, T; Graves, S; Greaves, J; Griffin, M; Gu, QL; Han, IL; Hoang, T; Houde, M; Hull, CLH; Inoue, T; Inutsuka, S; Iwasaki, K; Jeong, IG; Johnstone, D; Koenyves, V; Kang, JH; Kang, MJ; Kataoka, A; Kawabata, K; Kemper, F; Kim, J; Kim, S; Kim, G; Kim, KH; Kim, MR; Kim, KT; Kim, H; Kirchschlager, F; Kobayashi, MIN; Koch, PM; Kusune, T; Kwon, J; Lacaille, K; Law, CY; Lee, CW; Lee, HYS; Lee, YH; Lee, CF; Lee, JE; Lee, SS; Li, DL; Li, D; Li, GX; Li, HB; Lin, SJ; Liu, HL; Liu, T; Liu, SY; Liu, JH; Longmore, S; Lu, X; Lyo, AR; Mairs, S; Matsumura, M; Matthews, B; Moriarty-Schieven, G; Nagata, T; Nakamura, F; Nakanishi, H; Ngoc, NB; Ohashi, N; Onaka, T; Park, G; Parsons, H; Peretto, N; Priestley, F; Pyo, TS; Qian, L; Rao, RMS; Rawlings, J; Rawlings, M; Retter, B; Richer, J; Rigby, A; Sadavoy, S; Saito, H; Savini, G; Seta, M; Sharma, E; Shimajiri, Y; Shinnaga, H; Tahani, M; Tamura, M; Tang, YW; Tang, XD; Tomisaka, K; Tram, L; Tsukamoto, Y; Viti, S; Wang, HC; Wu, JT; Xie, JJ; Yang, MZ; Yen, HW; Yoo, H; Yuan, JH; Yun, HS; Zenko, T; Zhang, GY; Zhang, YP; Zhang, CP; Zhou, JJ; Zhu, L; de Looze, I; Andre, P; Dowell, CD; Eden, D; Eyres, S; Falle, S; Le Gouellec, VJM; Poidevin, F; Robitaille, JF; van Loo, S

ASTROPHYSICAL JOURNAL Vol. 952 ( 1 ) 2023.7

Fujimoto, Y; Inutsuka, SI; Baba, J

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 523 ( 2 ) page： 3049 - 3068 2023.5

Publisher：Monthly Notices of the Royal Astronomical Society

Stars in the Galactic disc, including the Solar system, have deviated from their birth orbits and have experienced radial mixing and vertical heating. By performing hydrodynamical simulations of a galactic disc, we investigate how much tracer particles, which are initially located in the disc to mimic newborn stars and the thin and thick disc stars, are displaced from initial near-circular orbits by gravitational interactions with giant molecular clouds (GMCs). To exclude the influence of other perturbers that can change the stellar orbits, such as spiral arms and the bar, we use an axisymmetric form for the entire galactic potential. First, we investigate the time evolution of the radial and vertical velocity dispersion σ<inf>R</inf> and σ<inf>z</inf> by comparing them with a power-law relation of σ ∝ tβ. Although the exponents β decrease with time, they keep large values of 0.3 ∼ 0.6 for 1 Gyr, indicating fast and efficient disc heating. Next, we find that the efficient stellar scattering by GMCs also causes a change in angular momentum for each star and, therefore, radial migration. This effect is more pronounced in newborn stars than old disc stars; nearly 30 per cent of stars initially located on the galactic mid-plane move more than 1 kpc in the radial direction for 1 Gyr. The dynamical heating and radial migration drastically occur in the first several hundred Myr. As the amplitude of the vertical oscillation increases, the time spent in the galactic plane, where most GMCs are distributed, decreases, and the rate of an increase in the heating and migration slows down.

DOI： 10.1093/mnras/stad1612

First BISTRO Observations of the Dark Cloud Taurus L1495A-B10: The Role of the Magnetic Field in the Earliest Stages of Low-mass Star Formation Open Access

Ward-Thompson, D; Karoly, J; Pattle, K; Whitworth, A; Kirk, J; Berry, D; Bastien, P; Ching, TC; Coudé, S; Hwang, J; Kwon, W; Soam, A; Wang, JW; Hasegawa, T; Lai, SP; Qiu, KP; Arzoumanian, D; Bourke, TL; Byun, D; Chen, HRV; Chen, WP; Chen, MK; Chen, ZW; Cho, JY; Choi, M; Choi, Y; Choi, Y; Chrysostomou, A; Chung, EJ; Dai, SP; Debattista, V; Di Francesco, J; Diep, PN; Doi, Y; Duan, HY; Duan, Y; Eswaraiah, C; Fanciullo, L; Fiege, J; Fissel, LM; Franzmann, E; Friberg, P; Friesen, R; Fuller, G; Furuya, R; Gledhill, T; Graves, S; Greaves, J; Griffin, M; Gu, QL; Han, IL; Hayashi, S; Hoang, T; Houde, M; Hull, CLH; Inoue, T; Inutsuka, S; Iwasaki, K; Jeong, I; Johnstone, D; Könyves, V; Kang, JH; Kang, MJ; Kataoka, A; Kawabata, K; Kemper, F; Kim, J; Kim, S; Kim, G; Kim, KH; Kim, MR; Kim, KT; Kim, H; Kirchschlager, F; Kobayashi, MIN; Koch, PM; Kusune, T; Kwon, J; Lacaille, K; Law, CY; Lee, CW; Lee, HYS; Lee, YH; Lee, CF; Lee, JE; Lee, SS; Li, DL; Li, D; Li, GX; Li, HB; Lin, SJ; Liu, HL; Liu, T; Liu, SY; Liu, JH; Longmore, S; Lu, X; Lyo, AR; Mairs, S; Matsumura, M; Matthews, B; Moriarty-Schieven, G; Nagata, T; Nakamura, F; Nakanishi, H; Ngoc, NB; Ohashi, N; Onaka, T; Park, G; Parsons, H; Peretto, N; Priestley, F; Pyo, TS; Qian, L; Rao, RMS; Rawlings, J; Rawlings, M; Retter, B; Richer, J; Rigby, A; Sadavoy, S; Saito, H; Savini, G; Seta, M; Shimajiri, Y; Shinnaga, H; Tahani, M; Tamura, M; Tang, YW; Tang, XD; Tomisaka, K; Tram, L; Tsukamoto, Y; Viti, S; Wang, HC; Wu, JT; Xie, JJ; Yang, MZ; Yen, HW; Yoo, H; Yuan, JH; Yun, HS; Zenko, T; Zhang, GY; Zhang, YP; Zhang, CP; Zhou, JJ; Zhu, L; de Looze, I; André, P; Dowell, CD; Eden, D; Eyres, S; Falle, S; Le Gouellec, VJM; Poidevin, F; Robitaille, JF; van Loo, S

ASTROPHYSICAL JOURNAL Vol. 946 ( 2 ) 2023.4

An Origin of Narrow Extended Structure in the Interstellar Medium: An Interstellar Contrail Created by a Fast-moving Massive Object Open Access

Kitajima, K; Inutsuka, SI

ASTROPHYSICAL JOURNAL Vol. 945 ( 1 ) 2023.3

Publisher：Astrophysical Journal

We investigate the thermal condensation caused by a massive object that passes through the interstellar medium with high velocity, and propose a mechanism for creating a filamentary gaseous object, or interstellar contrail. Our main result shows that a long interstellar contrail can form with a certain parameter; a compact object more massive than 104 M <inf>☉</inf> can make a filament whose length is larger than 100 pc. Observation of interstellar contrails may provide information on the number, masses, and velocities of fast-moving massive objects, and can be a new method for probing invisible gravitating sources such as intermediate-mass black holes.

DOI： 10.3847/1538-4357/acb7ea

Planetesimal Formation by the Gravitational Instability of Dust Ring Structures Open Access

Takahashi, SZ; Kokubo, E; Inutsuka, S

ASTROPHYSICAL JOURNAL Vol. 945 ( 2 ) 2023.3

Publisher：Astrophysical Journal

We investigate the gravitational instability (GI) of dust ring structures and the formation of planetesimals by their gravitational collapse. The normalized dispersion relation of a self-gravitating ring structure includes two parameters that are related to its width and line mass (the mass per unit length). We survey these parameters and calculate the growth rate and wavenumber. Additionally, we investigate the formation of planetesimals by growth of the GI of the ring that is formed by the growth of the secular GI of the protoplanetary disk. We adopt a massive, dust-rich disk as a disk model. We find the range of radii for fragmentation by the ring GI as a function of the width of the ring. The innermost radius for the ring GI is smaller for a smaller ring width. We also determine the range of the initial planetesimal mass resulting from the fragmentation of the ring GI. Our results indicate that the planetesimal mass can be as large as 1028 g at its birth after the fragmentation. It can be as low as about 1025 g if the ring width is 0.1% of the ring radius, and the lower limit increases with the ring width. Furthermore, we obtain approximate formulae for the upper and lower limits of the planetesimal mass. We predict that the planetesimals formed by the ring GI have prograde rotations because of the Coriolis force acting on the contracting dust. This is consistent with the fact that many trans-Neptunian binaries exhibit prograde rotation.

DOI： 10.3847/1538-4357/ac9fd0

Evolution of the Angular Momentum of Molecular Cloud Cores Formed from Filament Fragmentation International coauthorship Open Access

Misugi, Y; Inutsuka, S; Arzoumanian, D

ASTROPHYSICAL JOURNAL Vol. 943 ( 2 ) 2023.2

Publisher：Astrophysical Journal

The angular momentum of molecular cloud cores plays an important role in the process of star formation. However, the time evolution of the angular momentum of molecular cloud cores is still unclear. In this paper, we perform three-dimensional simulations to investigate the time evolution of the angular momentum of molecular cloud cores formed through filament fragmentation. As a result, we find that most of the cores rotate perpendicular to the filament axis. The mean angular momentum of the cores changes by only around 30% during the initial stage of their formation process and then remains almost constant. In addition, we analyze the internal angular momentum structure of the cores. Although the cores gain angular momentum with various directions from the initial turbulent velocity fluctuations of their parent filaments, the angular momentum profile in each core converges to the self-similar solution. We also show that the degree of complexity of the angular momentum structure in a core decreases slightly with time. Moreover, we perform synthetic observations and show that the angular momentum profile measured from the synthetic mean velocity map is compatible with the observations when the filament inclination is taken into account. The present study suggests a theory of core formation from filament fragmentation where the angular momentum structures of the cores are determined by the velocity fluctuation along the filaments and both are compatible with the observations. This theory also provides new insights into the core properties that could be tested observationally.

DOI： 10.3847/1538-4357/aca88d

JCMT BISTRO Observations: Magnetic Field Morphology of Bubbles Associated with NGC 6334 Open Access

Tahani, M; Bastien, P; Furuya, RS; Pattle, K; Johnstone, D; Arzoumanian, D; Doi, Y; Hasegawa, T; Inutsuka, S; Coudé, S; Fissel, L; Chen, MCY; Poidevin, F; Sadavoy, S; Friesen, R; Koch, PM; Di Francesco, J; Moriarty-Schieven, GH; Chen, ZW; Chung, EJ; Eswaraiah, C; Fanciullo, L; Gledhill, T; Le Gouellec, VJM; Hoang, T; Hwang, J; Kang, JH; Kim, KH; Kirchschlager, F; Kwon, W; Lee, CW; Liu, HL; Onaka, T; Rawlings, MG; Soam, A; Tamura, M; Tang, XD; Tomisaka, K; Whitworth, AP; Kwon, J; Hoang, TD; Redman, M; Berry, D; Ching, TC; Wang, JW; Lai, SP; Qiu, KP; Ward-Thompson, D; Houde, M; Byun, D; Chen, HRV; Chen, WP; Cho, JY; Choi, M; Choi, Y; Chrysostomou, A; Diep, PN; Duan, HY; Fiege, J; Franzmann, E; Friberg, P; Fuller, G; Graves, SF; Greaves, JS; Griffin, MJ; Gu, QL; Han, IL; Hatchell, J; Hayashi, SS; Hull, CLH; Inoue, T; Iwasaki, K; Jeong, I; Kanamori, Y; Kang, MJ; Kang, SJ; Kataoka, A; Kawabata, KS; Kemper, F; Kim, G; Kim, J; Kim, KT; Kim, MR; Kim, S; Kirk, JM; Kobayashi, MIN; Konyves, V; Kusune, T; Lacaille, K; Law, CY; Lee, CF; Lee, HYS; Lee, JE; Lee, SS; Lee, YH; Li, DL; Li, D; Li, HB; Liu, JH; Liu, SY; Liu, T; de Looze, I; Lyo, AR; Mairs, S; Matsumura, M; Matthews, BC; Nagata, T; Nakamura, F; Nakanishi, H; Ohashi, N; Park, G; Parsons, H; Peretto, N; Pyo, TS; Qian, L; Rao, RMS; Retter, B; Richer, J; Rigby, A; Saito, H; Savini, G; Scaife, AMM; Seta, M; Shimajiri, Y; Shinnaga, H; Tang, YW; Tsukamoto, Y; Viti, S; Wang, HC; Yen, HW; Yoo, H; Yuan, JH; Yun, HS; Zenko, T; Zhang, CP; Zhang, GY; Zhang, YP; Zhou, JJ; Zhu, L; André, P; Dowell, CD; Eyres, SPS; Falle, S; van Loo, S; Robitaille, JF

ASTROPHYSICAL JOURNAL Vol. 944 ( 2 ) 2023.2

Publisher：Astrophysical Journal

We study the Hii regions associated with the NGC 6334 molecular cloud observed in the submillimeter and taken as part of the B-fields In STar-forming Region Observations Survey. In particular, we investigate the polarization patterns and magnetic field morphologies associated with these Hii regions. Through polarization pattern and pressure calculation analyses, several of these bubbles indicate that the gas and magnetic field lines have been pushed away from the bubble, toward an almost tangential (to the bubble) magnetic field morphology. In the densest part of NGC 6334, where the magnetic field morphology is similar to an hourglass, the polarization observations do not exhibit observable impact from Hii regions. We detect two nested radial polarization patterns in a bubble to the south of NGC 6334 that correspond to the previously observed bipolar structure in this bubble. Finally, using the results of this study, we present steps (incorporating computer vision; circular Hough transform) that can be used in future studies to identify bubbles that have physically impacted magnetic field lines.

DOI： 10.3847/1538-4357/acac81

The JCMT BISTRO-2 Survey: Magnetic Fields of the Massive DR21 Filament International coauthorship Open Access

Ching, TC; Qiu, K; Li, D; Ren, ZY; Lai, SP; Berry, D; Pattle, K; Furuya, R; Ward-Thompson, D; Johnstone, D; Koch, PM; Lee, CW; Hoang, T; Hasegawa, T; Kwon, W; Bastien, P; Eswaraiah, C; Wang, JW; Kim, KH; Hwang, J; Soam, A; Lyo, AR; Liu, JH; Le Gouellec, VJM; Arzoumanian, D; Whitworth, A; Di Francesco, J; Poidevin, F; Liu, T; Coudé, S; Tahani, M; Liu, HL; Onaka, T; Li, DL; Tamura, M; Chen, ZW; Tang, XD; Kirchschlager, F; Bourke, TL; Byun, DY; Chen, MK; Chen, HRV; Chen, WP; Cho, J; Choi, Y; Choi, Y; Choi, M; Chrysostomou, A; Chung, EJ; Dai, YS; Diep, PN; Doi, Y; Duan, Y; Duan, HY; Eden, D; Fanciullo, L; Fiege, J; Fissel, LM; Franzmann, E; Friberg, P; Friesen, R; Fuller, G; Gledhill, T; Graves, S; Greaves, J; Griffin, M; Gu, QL; Han, I; Hayashi, S; Houde, M; Hull, CLH; Inoue, T; Inutsuka, SI; Iwasaki, K; Jeong, IG; Könyves, V; Kang, JH; Kang, M; Karoly, J; Kataoka, A; Kawabata, K; Kemper, F; Kim, J; Kim, MR; Kim, S; Kim, H; Kim, KT; Kim, G; Kirk, J; Kobayashi, MIN; Kusune, T; Kwon, J; Lacaille, K; Law, CY; Lee, SS; Lee, H; Lee, JE; Lee, CF; Lee, YH; Li, GX; Li, HB; Lin, SJ; Liu, SY; Lu, X; Mairs, S; Matsumura, M; Matthews, B; Moriarty-Schieven, G; Nagata, T; Nakamura, F; Nakanishi, H; Ngoc, NB; Ohashi, N; Park, G; Parsons, H; Peretto, N; Priestley, F; Pyo, TS; Qian, L; Rao, R; Rawlings, M; Rawlings, J; Retter, B; Richer, J; Rigby, A; Sadavoy, S; Saito, H; Savini, G; Seta, M; Shimajiri, Y; Shinnaga, H; Tang, YW; Tomisaka, K; Tram, LN; Tsukamoto, Y; Viti, S; Wang, HC; Wu, JT; Xie, JJ; Yang, MZ; Yen, HW; Yoo, H; Yuan, JH; Yun, HS; Zenko, T; Zhang, CP; Zhang, YP; Zhang, GY; Zhou, JJ; Zhu, L; De Looze, I; André, P; Dowell, CD; Eyres, S; Falle, S; Robitaille, JF; Van Loo, S

ASTROPHYSICAL JOURNAL Vol. 941 ( 2 ) 2022.12

Publisher：Astrophysical Journal

We present 850 μm dust polarization observations of the massive DR21 filament from the B-fields In STar-forming Region Observations (BISTRO) survey, using the POL-2 polarimeter and the SCUBA-2 camera on the James Clerk Maxwell Telescope. We detect ordered magnetic fields perpendicular to the parsec-scale ridge of the DR21 main filament. In the subfilaments, the magnetic fields are mainly parallel to the filamentary structures and smoothly connect to the magnetic fields of the main filament. We compare the POL-2 and Planck dust polarization observations to study the magnetic field structures of the DR21 filament on 0.1-10 pc scales. The magnetic fields revealed in the Planck data are well-aligned with those of the POL-2 data, indicating a smooth variation of magnetic fields from large to small scales. The plane-of-sky magnetic field strengths derived from angular dispersion functions of dust polarization are 0.6-1.0 mG in the DR21 filament and ∼0.1 mG in the surrounding ambient gas. The mass-to-flux ratios are found to be magnetically supercritical in the filament and slightly subcritical to nearly critical in the ambient gas. The alignment between column density structures and magnetic fields changes from random alignment in the low-density ambient gas probed by Planck to mostly perpendicular in the high-density main filament probed by James Clerk Maxwell Telescope. The magnetic field structures of the DR21 filament are in agreement with MHD simulations of a strongly magnetized medium, suggesting that magnetic fields play an important role in shaping the DR21 main filament and subfilaments.

DOI： 10.3847/1538-4357/ac9dfb

The JCMT BISTRO Survey: A Spiral Magnetic Field in a Hub-filament Structure, Monoceros R2 Reviewed International coauthorship Open Access

Hwang, J; Kim, J; Pattle, K; Lee, CW; Koch, PM; Johnstone, D; Tomisaka, K; Whitworth, A; Furuya, RS; Kang, JH; Lyo, AR; Chung, EJ; Arzoumanian, D; Park, G; Kwon, W; Kim, S; Tamura, M; Kwon, J; Soam, A; Han, I; Hoang, T; Kim, KH; Onaka, T; Eswaraiah, C; Ward-Thompson, D; Liu, HL; Tang, XD; Chen, WP; Matsumura, M; Hoang, TD; Chen, ZW; Le Gouellec, VJM; Kirchschlager, F; Poidevin, F; Bastien, P; Qiu, K; Hasegawa, T; Lai, SP; Byun, DY; Cho, J; Choi, M; Choi, Y; Choi, Y; Jeong, IG; Kang, M; Kim, H; Kim, KT; Lee, JE; Lee, SS; Lee, YH; Lee, H; Kim, MR; Yoo, H; Yun, HS; Chen, M; Di Francesco, J; Fiege, J; Fissel, LM; Franzmann, E; Houde, M; Lacaille, K; Matthews, B; Sadavoy, S; Moriarty-Schieven, G; Tahani, M; Ching, TC; Dai, YS; Duan, Y; Gu, QL; Law, CY; Li, DLL; Li, D; Li, GX; Li, HB; Liu, T; Lu, X; Qian, L; Wang, HC; Wu, JT; Xie, JJ; Yuan, JH; Zhang, CP; Zhang, GY; Zhang, YP; Zhou, J; Zhu, L; Berry, D; Friberg, P; Graves, S; Liu, JH; Mairs, S; Parsons, H; Rawlings, M; Doi, Y; Hayashi, S; Hull, CLH; Inoue, T; Inutsuka, S; Iwasaki, K; Kataoka, A; Kawabata, K; Kim, G; Kobayashi, MIN; Nagata, T; Nakamura, F; Nakanishi, H; Pyo, TS; Saito, H; Seta, M; Shimajiri, Y; Shinnaga, H; Tsukamoto, Y; Zenko, T; Chen, HRV; Duan, HY; Fanciullo, L; Kemper, F; Lee, CF; Lin, SJ; Liu, SY; Ohashi, N; Rao, R; Tang, YW; Wang, JW; Yang, MZ; Yen, HW; Bourke, TL; Chrysostomou, A; Debattista, V; Eden, D; Eyres, S; Falle, S; Fuller, G; Gledhill, T; Greaves, J; Griffin, M; Hatchell, J; Karoly, J; Kirk, J; Könyves, V; Longmore, S; van Loo, S; de Looze, I; Peretto, N; Priestley, F; Rawlings, J; Retter, B; Richer, J; Rigby, A; Savini, G; Scaife, A; Viti, S; Diep, PN; Ngoc, NB; Tram, LN; André, P; Coudé, S; Dowell, CD; Friesen, R; Robitaille, JF

ASTROPHYSICAL JOURNAL Vol. 941 ( 1 ) 2022.12

Language：English Publisher：Astrophysical Journal

We present and analyze observations of polarized dust emission at 850 μm toward the central 1 × 1 pc hub-filament structure of Monoceros R2 (Mon R2). The data are obtained with SCUBA-2/POL-2 on the James Clerk Maxwell Telescope (JCMT) as part of the B-fields in Star-forming Region Observations survey. The orientations of the magnetic field follow the spiral structure of Mon R2, which are well described by an axisymmetric magnetic field model. We estimate the turbulent component of the magnetic field using the angle difference between our observations and the best-fit model of the underlying large-scale mean magnetic field. This estimate is used to calculate the magnetic field strength using the Davis–Chandrasekhar–Fermi method, for which we also obtain the distribution of volume density and velocity dispersion using a column density map derived from Herschel data and the C18O (J = 3 - 2) data taken with HARP on the JCMT, respectively. We make maps of magnetic field strengths and mass-to-flux ratios, finding that magnetic field strengths vary from 0.02 to 3.64 mG with a mean value of 1.0 ± 0.06 mG, and the mean critical mass-to-flux ratio is 0.47 ± 0.02. Additionally, the mean Alfvén Mach number is 0.35 ± 0.01. This suggests that, in Mon R2, the magnetic fields provide resistance against large-scale gravitational collapse, and the magnetic pressure exceeds the turbulent pressure. We also investigate the properties of each filament in Mon R2. Most of the filaments are aligned along the magnetic field direction and are magnetically subcritical.

DOI： 10.3847/1538-4357/ac99e0

Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks. II. Dust-ring Formation Mediated by Backreaction and Fragmentation Open Access

Tominaga, RT; Tanaka, H; Kobayashi, H; Inutsuka, S

ASTROPHYSICAL JOURNAL Vol. 940 ( 2 ) 2022.12

Publisher：Astrophysical Journal

In our previous work (Paper I), we demonstrated that coagulation instability results in dust concentration against depletion due to the radial drift and accelerates dust growth locally. In this work (Paper II), we perform numerical simulations of coagulation instability taking into account effects of backreaction to gas and collisional fragmentation of dust grains. We find that the slowdown of the dust drift due to backreaction regulates dust concentration in the nonlinear growth phase of coagulation instability. The dust-to-gas surface density ratio increases from 10−3 up to ∼10−2. Each resulting dust ring tends to have a mass of ≃0.5 M <inf>⊕</inf> − 1.5 M <inf>⊕</inf> in our disk model. In contrast to Paper I, the dust surface density profile shows a local plateau structure at each dust ring. In spite of the regulation at the nonlinear growth, the efficient dust concentration reduces their collision velocity. As a result, dust grains can grow beyond the fragmentation barrier, and the dimensionless stopping time reaches unity, as in Paper I. The necessary condition for the efficient dust growth is (1) weak turbulence of α < 1 × 10−3 and (2) a large critical velocity for dust fragmentation (>1 m s−1). The efficient dust concentration in outer regions will reduce the inward pebble flux and is expected to decelerate the planet formation via the pebble accretion. We also find that the resulting rings can be unstable to secular gravitational instability (GI). The subsequent secular GI promotes planetesimal formation. We thus expect that a combination of these instabilities is a promising mechanism for dust-ring and planetesimal formation.

DOI： 10.3847/1538-4357/ac97e8

Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks. I. First Numerical Study of Accelerated Dust Growth and Dust Concentration at Outer Radii Reviewed International coauthorship Open Access

Tominaga, RT; Kobayashi, H; Inutsuka, S

ASTROPHYSICAL JOURNAL Vol. 937 ( 1 ) 2022.9

Language：English Publisher：Astrophysical Journal

Our previous linear analysis presents a new instability driven by dust coagulation in protoplanetary disks. The coagulation instability has the potential to concentrate dust grains into rings and assist dust coagulation and planetesimal formation. In this series of papers, we perform numerical simulations and investigate the nonlinear outcome of coagulation instability. In this paper (Paper I), we first conduct local simulations to demonstrate the existence of coagulation instability. Linear growth observed in the simulations is in good agreement with the previous linear analysis. We next conduct radially global simulations to demonstrate that coagulation instability develops during the inside-out disk evolution owing to dust growth. To isolate the various effects on dust concentration and growth, we neglect the effects of back-reaction to a gas disk and dust fragmentation in Paper I. This simplified simulation shows that neither back-reaction nor fragmentation is a prerequisite for local dust concentration via the instability. In most runs with weak turbulence, dust concentration via coagulation instability overcomes dust depletion due to radial drift, leading to the formation of multiple dust rings. The nonlinear development of coagulation instability also accelerates dust growth, and the dimensionless stopping time τ <inf>s</inf> reaches unity even at outer radii (>10 au). Therefore, coagulation instability is one promising process to retain dust grains and to accelerate dust growth beyond the drift barrier.

DOI： 10.3847/1538-4357/ac82b4

On high-order numerical schemes for viscous relativistic hydrodynamics through the Kelvin-Helmholtz instability Reviewed International coauthorship Open Access

Townsend, JF; Inutsuka, S; Könözsy, L; Jenkins, KW

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 515 ( 1 ) page： 451 - 472 2022.7

Language：English Publisher：Monthly Notices of the Royal Astronomical Society

This work assesses the dissipative properties of high-order numerical methods for relativistic hydrodynamics. A causal theory of physical dissipation is included within a finite volume high-resolution shock-capturing framework based on the Israel-Stewart theory to study high-order WENO (weighted-essentially non-oscillatory) schemes for simulating the relativistic Kelvin-Helmholtz instability. We provide an estimation of the numerical dissipation of high-order schemes based on results obtained both with and without physically resolved dissipation and determine an empirical relationship between the numerical dissipation and the grid resolution. We consider the appearance of secondary flow features within the evolution of the Kelvin-Helmholtz instability and determine that they are numerical artifacts-This is partly based on arguments presented in terms of a frame-dependent form of the relativistic Reynolds number. There is a potential advantage of using high-order schemes in terms of their accuracy and computational cost on coarser grid resolutions when directly compared to low-order schemes on a fine grid in the presence of physical viscosity. It is possible to find reasonable agreement between numerical results that employ lower-order schemes using a finer grid resolution and results that employ higher order schemes at a coarser grid resolution when sufficient viscosity is present. Overall, the present analysis gives an insight into the numerical dissipation of high-order shock-wave capturing schemes which can be relevant to computational studies of astrophysical phenomena in the relativistic regime. The results presented herein are problem and scheme-dependent and serve to highlight the different roles of numerical and physical dissipation.

DOI： 10.1093/mnras/stac1741

Effects of Magnetic Field Orientations in Dense Cores on Gas Kinematics in Protostellar Envelopes Reviewed International coauthorship Open Access

Gupta, A; Yen, HW; Koch, P; Bastien, P; Bourke, TL; Chung, EJ; Hasegawa, T; Hull, CLH; Inutsuka, S; Kwon, J; Kwon, W; Lai, SP; Lee, CW; Lee, CF; Pattle, K; Qiu, KP; Tahani, M; Tamura, M; Ward-Thompson, D

ASTROPHYSICAL JOURNAL Vol. 930 ( 1 ) 2022.5

Language：English Publisher：Astrophysical Journal

Theoretically, misalignment between the magnetic field and rotational axis in a dense core is considered to be dynamically important in the star formation process; however, the extent of this influence remains observationally unclear. For a sample of 32 Class 0 and I protostars in the Perseus Molecular Cloud, we analyzed gas motions using C18O data from the SMA MASSES survey and the magnetic field structures using 850 μm polarimetric data from the JCMT BISTRO-1 survey and archive. We do not find any significant correlation between the velocity gradients in the C18O emission in the protostellar envelopes at a 1000 au scale and the misalignment between the outflows and magnetic field orientations in the dense cores at a 4000 au scale, and there is also no correlation between the velocity gradients and the angular dispersions of the magnetic fields. However, a significant dependence on the misalignment angles emerges after we normalize the rotational motion by the infalling motion, where the ratios increase from 21 to 31 with increasing misalignment angle. This suggests that the misalignment could prompt angular momentum transportation to the envelope scale but is not a dominant factor in determining the envelope rotation, and other parameters, such as mass accretion in protostellar sources, also play an important role. These results remain valid after taking into account projection effects. The comparison between our estimated angular momentum in the protostellar envelopes and the sizes of the known protostellar disks suggests that significant angular momentum is likely lost between radii of ∼1000 and 100 au in protostellar envelopes.

DOI： 10.3847/1538-4357/ac63bc