Papers - INUTSUKA, Shu-ichiro

The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333 (vol 899, 28, 2020) Open Access

Doi, Y; Hasegawa, T; Furuya, RS; Coudé, S; Hull, CLH; Arzoumanian, D; Bastien, P; Chen, MCY; Di Francesco, J; Friesen, R; Houde, M; Inutsuka, SI; Mairs, S; Matsumura, M; Onaka, T; Sadavoy, S; Shimajiri, Y; Tahani, M; Tomisaka, K; Eswaraiah, C; Koch, PM; Pattle, K; Lee, CW; Tamura, M; Berry, D; Ching, TC; Hwang, J; Kwon, W; Soam, A; Wang, JW; Lai, SP; Qiu, KP; Ward-Thompson, D; Byun, D; Chen, HRV; Chen, WP; Chen, ZW; Cho, J; Choi, M; Choi, Y; Chrysostomou, A; Chung, EJ; Diep, PN; Duan, HY; Fanciullo, L; Fiege, J; Franzmann, E; Friberg, P; Fuller, G; Gledhill, T; Graves, SF; Greaves, JS; Griffin, MJ; Gu, QL; Han, I; Hatchell, J; Hayashi, SS; Hoang, T; Inoue, T; Iwasaki, K; Jeong, I; Johnstone, D; Kanamori, Y; Kang, JH; Kang, M; Kang, SJ; Kataoka, A; Kawabata, KS; Kemper, F; Kim, G; Kim, J; Kim, KT; Kim, KH; Kim, MR; Kim, S; Kirk, JM; Kobayashi, MIN; Konyves, V; Kusune, T; Kwon, J; Lacaille, K; Law, CY; Lee, CF; Lee, H; Lee, JE; Lee, SS; Lee, YH; Li, DL; Li, D; Li, HB; Liu, HL; Liu, JH; Liu, SY; Liu, T; de Looze, I; Lyo, AR; Matthews, BC; Moriarty-Schieven, GH; Nagata, T; Nakamura, F; Nakanishi, H; Ohashi, N; Park, G; Parsons, H; Peretto, N; Pyo, TS; Qian, L; Rao, RM; Rawlings, MG; Retter, B; Richer, J; Rigby, A; Saito, H; Savini, G; Scaife, AMM; Seta, M; Shinnaga, H; Tang, YW; Tsukamoto, Y; Viti, S; Wang, HC; Whitworth, AP; 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. 911 ( 1 )   2021.4

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In the published article, we presented high-resolution polarimetry data obtained by using JCMT SCUBA-2/POL-2, and compared them with the larger-scale magnetic structure observed by Planck (Planck Collaboration et al. 2020). There was a miscalculation in the analysis of the Planck data for comparison, and the mean position angle of the Planck magnetic field should be corrected from -40° ± 7° to -48° ± 6°. Thus, we replace the descriptions in the published article as follows. In Section 4.2, paragraph 3, the second sentence should read: "The differences between the orientations of IRAS 4A, IRAS 4B, and IRAS 2A are not statistically significant, but they do show significantly different orientations from those of the global B-field observed by Planck (-48° ± 6°; Section 4.1)." In Section 4.1, paragraph 3, the second line should read: "The Planck B-field orientation shows a smoothly and slowly varying field distribution with a position angle of -48° ± 6° in our observed NGC 1333 area." Accordingly, we replace Figures 4, 5, 9, 10, and 17 to reflect the correct Planck data. As described above, this error of modest magnitude is related only to our derivation of the Planck polarization angle, and the JCMT observation results are unaffected. Therefore, all conclusions drawn in the published article are unchanged even after the above correction is applied. The 1 pc scale magnetic field observed by Planck shows a smooth distribution, and the interstellar magnetic field in molecular clouds increases the complexity significantly on the scale of less than 1 pc.

DOI： 10.3847/1538-4357/abf2b3

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OMC-1 dust polarization in ALMA Band 7: diagnosing grain alignment mechanisms in the vicinity of Orion Source I Open Access

Pattle Kate, Lai Shih-Ping, Wright Melvyn, Coude Simon, Plambeck Richard, Hoang Thiem, Tang Ya-Wen, Bastien Pierre, Eswaraiah Chakali, Furuya Ray S., Hwang Jihye, Inutsuka Shu-ichiro, Kim Kee-Tae, Kirchschlager Florian, Kwon Woojin, Lee Chang Won, Liu Sheng-Yuan, Lyo Aran, Ohashi Nagayoshi, Rawlings Mark G., Tahani Mehrnoosh, Tamura Motohide, Soam Archana, Wang Jia-Wei, Ward-Thompson Derek

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 503 ( 3 ) page： 3414 - 3433   2021.3

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DOI： 10.1093/mnras/stab608

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Dust polarized emission observations of NGC 6334 BISTRO reveals the details of the complex but organized magnetic field structure of the high-mass star-forming hub-filament network Reviewed International coauthorship Open Access

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

ASTRONOMY & ASTROPHYSICS   Vol. 647   2021.3

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Astronomy and Astrophysics  

Context. Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation. Methods. We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polarized intensity (PI), the polarization fraction (PF), and the plane-of-The-sky B-field angle (χB_POS) toward the whole region, along the 10 pc-long ridge and along the sub-filaments connected to the ridge and the hubs. We derived the power spectra of the intensity and χBPOS along the ridge crest and compared them with the results obtained from simulated filaments. Results. The observations span 3 orders of magnitude in Stokes I and PI and 2 orders of magnitude in PF (from 0.2 to 20%). A large scatter in PI and PF is observed for a given value of I. Our analyses show a complex B-field structure when observed over the whole region ( 10 pc); however, at smaller scales (1 pc), χBPOS varies coherently along the crests of the filament network. The observed power spectrum of χBPOS can be well represented with a power law function with a slope of-1.33 ± 0.23, which is 20% shallower than that of I. We find that this result is compatible with the properties of simulated filaments and may indicate the physical processes at play in the formation and evolution of star-forming filaments. Along the sub-filaments, χBPOS rotates frombeing mostly perpendicular or randomly oriented with respect to the crests to mostly parallel as the sub-filaments merge with the ridge and hubs. This variation of the B-field structure along the sub-filaments may be tracing local velocity flows of infalling matter in the ridge and hubs. Our analysis also suggests a variation in the energy balance along the crests of these sub-filaments, from magnetically critical or supercritical at their far ends to magnetically subcritical near the ridge and hubs. We also detect an increase in PF toward the high-column density (NH2 â 1023 cm-2) star cluster-forming hubs. These latter large PF values may be explained by the increase in grain alignment efficiency due to stellar radiation from the newborn stars, combined with an ordered B-field structure. Conclusions. These observational results reveal for the first time the characteristics of the small-scale (down to 0.1 pc) B-field structure of a 10 pc-long hub-filament system. Our analyses show variations in the polarization properties along the sub-filaments that may be tracing the evolution of their physical properties during their interaction with the ridge and hubs. We also detect an impact of feedback from young high-mass stars on the local B-field structure and the polarization properties, which could put constraints on possible models for dust grain alignment and provide important hints as to the interplay between the star formation activity and interstellar B-fields.

DOI： 10.1051/0004-6361/202038624

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ALMA Observations of Massive Clouds in the Central Molecular Zone: Ubiquitous Protostellar Outflows Reviewed International coauthorship Open Access

Lu, X; Li, SH; Ginsburg, A; Longmore, SN; Kruijssen, JMD; Walker, DL; Feng, SY; Zhang, QZ; Battersby, C; Pillai, T; Mills, EAC; Kauffmann, J; Cheng, Y; Inutsuka, S

ASTROPHYSICAL JOURNAL   Vol. 909 ( 2 )   2021.3

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We observe 1.3 mm spectral lines at 2000 au resolution toward four massive molecular clouds in the Central Molecular Zone (CMZ) of the Galaxy to investigate their star formation activities. We focus on several potential shock tracers that are usually abundant in protostellar outflows, including SiO, SO, CH3OH, H2CO, HC3N, and HNCO. We identify 43 protostellar outflows, including 37 highly likely ones and 6 candidates. The outflows are found toward both known high-mass star-forming cores and less massive, seemingly quiescent cores, while 791 out of the 834 cores identified based on the continuum do not have detected outflows. The outflow masses range from less than 1 M o˙ to a few tens of M o˙, with typical uncertainties of a factor of 70. We do not find evidence of disagreement between relative molecular abundances in these outflows and in nearby analogs such as the well-studied L1157 and NGC 7538S outflows. The results suggest that (i) protostellar accretion disks driving outflows ubiquitously exist in the CMZ environment, (ii) the large fraction of candidate starless cores is expected if these clouds are at very early evolutionary phases, with a caveat on the potential incompleteness of the outflows, (iii) high-mass and low-mass star formation is ongoing simultaneously in these clouds, and (iv) current data do not show evidence of a difference between the shock chemistry in the outflows that determines the molecular abundances in the CMZ environment and in nearby clouds.

DOI： 10.3847/1538-4357/abde3c

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FAUST. II. Discovery of a Secondary Outflow in IRAS 15398-3359: Variability in Outflow Direction during the Earliest Stage of Star Formation? Reviewed International coauthorship Open Access

Okoda, Y; Oya, Y; Francis, L; Johnstone, D; Inutsuka, S; Ceccarelli, C; Codella, C; Chandler, C; Sakai, N; Aikawa, Y; Alves, FO; Balucani, N; Bianchi, E; Bouvier, M; Caselli, P; Caux, E; Charnley, S; Choudhury, S; De Simone, M; Dulieu, F; Durán, A; Evans, L; Favre, C; Fedele, D; Feng, SY; Fontani, F; Hama, T; Hanawa, T; Herbst, E; Hirota, T; Imai, M; Isella, A; Jímenez-Serra, I; Kahane, C; Lefloch, B; Loinard, L; López-Sepulcre, A; Maud, LT; Maureira, MJ; Menard, F; Mercimek, S; Miotello, A; Moellenbrock, G; Mori, S; Murillo, NM; Nakatani, R; Nomura, H; Oba, Y; O'Donoghue, R; Ohashi, S; Ospina-Zamudio, J; Pineda, JE; Podio, L; Rimola, A; Sakai, T; Segura-Cox, D; Shirley, Y; Svoboda, B; Taquet, V; Testi, L; Vastel, C; Viti, S; Watanabe, N; Watanabe, Y; Witzel, A; Xue, C; Zhang, YC; Zhao, B; Yamamoto, S

ASTROPHYSICAL JOURNAL   Vol. 910 ( 1 )   2021.3

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We have observed the very low-mass Class 0 protostar IRAS 15398-3359 at scales ranging from 50 to 1800 au, as part of the Atacama Large Millimeter/Submillimeter Array Large Program FAUST. We uncover a linear feature, visible in H2CO, SO, and C18O line emission, which extends from the source in a direction almost perpendicular to the known active outflow. Molecular line emission from H2CO, SO, SiO, and CH3OH further reveals an arc-like structure connected to the outer end of the linear feature and separated from the protostar, IRAS 15398-3359, by 1200 au. The arc-like structure is blueshifted with respect to the systemic velocity. A velocity gradient of 1.2 km s-1 over 1200 au along the linear feature seen in the H2CO emission connects the protostar and the arc-like structure kinematically. SO, SiO, and CH3OH are known to trace shocks, and we interpret the arc-like structure as a relic shock region produced by an outflow previously launched by IRAS 15398-3359. The velocity gradient along the linear structure can be explained as relic outflow motion. The origins of the newly observed arc-like structure and extended linear feature are discussed in relation to turbulent motions within the protostellar core and episodic accretion events during the earliest stage of protostellar evolution.

DOI： 10.3847/1538-4357/abddb1

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Observations of Magnetic Fields Surrounding LkH<i>α</i> 101 Taken by the BISTRO Survey with JCMT-POL-2 Reviewed International coauthorship Open Access

Ngoc, NB; Diep, PN; Parsons, H; Pattle, K; Hoang, T; Ward-Thompson, D; Tram, LN; Hull, CLH; Tahani, M; Furuya, R; Bastien, P; Qiu, KP; Hasegawa, T; Kwon, W; Doi, Y; Lai, SP; Coudé, S; Berry, D; Ching, TC; Hwang, J; Soam, A; Wang, JW; Arzoumanian, D; Bourke, TL; Byun, D; Chen, HRV; Chen, ZW; Chen, WP; Chen, MK; Cho, J; Choi, Y; Choi, M; Chrysostomou, A; Chung, EJ; Dai, SP; Di Francesco, J; Duan, Y; Duan, HY; Eden, D; Eswaraiah, C; 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; Hatchell, J; Hayashi, S; Houde, M; Inoue, T; Inutsuka, S; Iwasaki, K; Jeong, IG; Johnstone, D; Kang, JH; Kang, SJ; Kang, M; Kataoka, A; Kawabata, K; Kemper, F; Kim, KT; Kim, J; Pyo, TS; Qian, L; Rao, RM; Rawlings, M; Rawlings, J; Retter, B; Richer, J; Rigby, A; Sadavoy, S; Saito, H; Savini, G; Scaife, A; Seta, M; Kim, G; Kim, S; Kim, KH; Kim, MR; Kirchschlager, F; Kirk, J; Kobayashi, MIN; Koch, PM; Konyves, V; Kusune, T; Kwon, J; Lacaille, K; Law, CY; Lee, SS; Lee, YH; Lee, CF; Lee, JE; Lee, H; Lee, CW; Li, D; Li, HB; Li, DL; Liu, HL; Liu, JH; Liu, T; Liu, SY; Lu, X; Lyo, AR; Mairs, S; Matsumura, M; Matthews, B; Moriarty-Schieven, G; Nagata, T; Nakamura, F; Nakanishi, H; Ohashi, N; Onaka, T; Park, G; Peretto, N; Shimajiri, Y; Shinnaga, H; Tamura, M; Tang, YW; Tang, XD; Tomisaka, K; Tsukamoto, Y; Viti, S; Wang, HC; Whitworth, A; Xie, JJ; Yen, HW; Yoo, H; Yuan, JH; Yun, HS; Zenko, T; Zhang, YP; Zhang, CAP; 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. 908 ( 1 )   2021.2

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We report the first high spatial resolution measurement of magnetic fields surrounding LkHa 101, part of the Auriga- California molecular cloud. The observations were taken with the POL-2 polarimeter on the James Clerk Maxwell Telescope within the framework of the B-fields In Star-forming Region Observations (BISTRO) survey. Observed polarization of thermal dust emission at 850 μm is found to be mostly associated with the redshifted gas component of the cloud. The magnetic field displays a relatively complex morphology. Two variants of the Davis-Chandrasekhar- Fermi method, unsharp masking and structure function, are used to calculate the strength of magnetic fields in the plane of the sky, yielding a similar result of BPOS~ 115 μG. The mass-to-magnetic-flux ratio in critical value units, λ~0.3, is the smallest among the values obtained for other regions surveyed by POL-2. This implies that the LkHa 101 region is subcritical, and the magnetic field is strong enough to prevent gravitational collapse. The inferred dB/B0~0.3 implies that the large-scale component of the magnetic field dominates the turbulent one. The variation of the polarization fraction with total emission intensity can be fitted by a power law with an index of a =0.82±0.03, which lies in the range previously reported for molecular clouds. We find that the polarization fraction decreases rapidly with proximity to the only early B star (LkHa 101) in the region. Magnetic field tangling and the joint effect of grain alignment and rotational disruption by radiative torques can potentially explain such a decreasing trend.

DOI： 10.3847/1538-4357/abd0fc

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The JCMT BISTRO Survey: Alignment between Outflows and Magnetic Fields in Dense Cores/Clumps Reviewed International coauthorship Open Access

Yen, HW; Koch, PM; Hull, CLH; Ward-Thompson, D; Bastien, P; Hasegawa, T; Kwon, W; Lai, SP; Qiu, KP; Ching, TC; Chung, EJ; Coudé, S; Di Francesco, J; Diep, PN; Doi, Y; Eswaraiah, C; Falle, S; Fuller, G; Furuya, RS; Han, I; Hatchell, J; Houde, M; Inutsuka, SI; Johnstone, D; Kang, JH; Kang, M; Kim, KT; Kirchschlager, F; Kwon, J; Lee, CW; Lee, CF; Liu, HL; Liu, T; Lyo, AR; Ohashi, N; Onaka, T; Pattle, K; Sadavoy, S; Saito, H; Shinnaga, H; Soam, A; Tahani, M; Tamura, M; Tang, YW; Tang, XD; Zhang, CP

ASTROPHYSICAL JOURNAL   Vol. 907 ( 1 )   2021.1

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We compare the directions of molecular outflows of 62 low-mass Class 0 and I protostars in nearby (<450 pc) star-forming regions with the mean orientations of the magnetic fields on 0.05-0.5 pc scales in the dense cores/clumps where they are embedded. The magnetic field orientations were measured using the JCMT POL-2 data taken by the BISTRO-1 survey and from the archive. The outflow directions were observed with interferometers in the literature. The observed distribution of the angles between the outflows and the magnetic fields peaks between 15° and 35°. After considering projection effects, our results could suggest that the outflows tend to be misaligned with the magnetic fields by 50° ± 15° in three-dimensional space and are less likely (but not ruled out) randomly oriented with respect to the magnetic fields. There is no correlation between the misalignment and the bolometric temperatures in our sample. In several sources, the small-scale (1000-3000 au) magnetic field is more misaligned with the outflow than the large-scale magnetic field, suggesting that the small-scale magnetic field has been twisted by the dynamics. In comparison with turbulent MHD simulations of core formation, our observational results are more consistent with models in which the energy densities in the magnetic field and the turbulence of the gas are comparable. Our results also suggest that the misalignment alone cannot sufficiently reduce the efficiency of magnetic braking to enable formation of the observed number of large Keplerian disks with sizes larger than 30-50 au.

DOI： 10.3847/1538-4357/abca99

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Progress in Star Formation Theory Invited Reviewed Open Access

犬塚 修一郎

The Astronomical Herald   Vol. 114   page： 109 - 119   2021

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Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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CiNii Research

Star Formation in The Galactic Disk and The Galactic Center Invited Reviewed International journal Open Access

犬塚 修一郎

ASP Conference Series, Vol. 528: New Horizons in Galactic Center Astronomy and Beyond   Vol. 528   page： 271 - 280   2021

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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CiNii Research

ALMA CO Observations of the Gamma-Ray Supernova Remnant RX J1713.7-3946: Discovery of Shocked Molecular Cloudlets and Filaments at 0.01 pc Scales Reviewed International coauthorship Open Access

Sano, H; Inoue, T; Tokuda, K; Tanaka, T; Yamazaki, R; Inutsuka, S; Aharonian, F; Rowell, G; Filipovic, MD; Yamane, Y; Yoshiike, S; Maxted, N; Uchida, H; Hayakawa, T; Tachihara, K; Uchiyama, Y; Fukui, Y

ASTROPHYSICAL JOURNAL LETTERS   Vol. 904 ( 2 )   2020.12

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RX J1713.7-3946 is a unique core-collapse supernova remnant (SNR) that emits bright TeV gamma-rays and synchrotron X-rays caused by cosmic rays, in addition to interactions with interstellar gas clouds. We report here on results of Atacama Large Millimeter/submillimeter Array 12CO(J = 1-0) observations toward the northwestern shell of the SNR. We newly found three molecular complexes consisting of dozens of shocked molecular cloudlets and filaments with typical radii of ∼0.03-0.05 pc and densities of ∼104 cm-3. These cloudlets and filaments are located not only along synchrotron X-ray filaments, but also in the vicinity of X-ray hotspots with month-or year-scale time variations. We argue that X-ray hotspots and filaments were generated by shock-cloudlet interactions through magnetic-field amplification up to mG. The interstellar medium density contrast of ∼105, coexistence of molecular cloudlets and low-density diffuse medium of ∼0.1 cm-3, is consistent with such a magnetic field amplification as well as a wind-bubble scenario. The small-scale cloud structures also affect hadronic gamma-ray spectra considering the magnetic field amplification on surface and inside clouds.

DOI： 10.3847/2041-8213/abc884

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Bimodal Behavior and Convergence Requirement in Macroscopic Properties of the Multiphase Interstellar Medium Formed by Atomic Converging Flows Reviewed Open Access

Kobayashi, MIN; Inoue, T; Inutsuka, S; Tomida, K; Iwasaki, K; Tanaka, KEI

ASTROPHYSICAL JOURNAL   Vol. 905 ( 2 )   2020.12

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We systematically perform hydrodynamics simulations of 20 km s-1 converging flows of the warm neutral medium (WNM) to calculate the formation of the cold neutral medium (CNM), focusing especially on the mean properties of the multiphase interstellar medium (ISM), such as the mean density on a 10 pc scale. Our results show that convergence in those mean properties requires a 0.02 pc spatial resolution that resolves the cooling length of the thermally unstable neutral medium (UNM) to follow the dynamical condensation from the WNM to the CNM. We also find that two distinct postshock states appear in the mean properties depending on the amplitude of the upstream WNM density fluctuation {equation presented}. When Δρ0 > 10 %, the interaction between shocks and density inhomogeneity leads to a strong driving of the postshock turbulence of >3 km s-1, which dominates the energy budget in the shock-compressed layer. The turbulence prevents dynamical condensation by cooling, and the CNM mass fraction remains at ∼45%. In contrast, when Δρ 0 ≥ 10%, the CNM formation proceeds efficiently, resulting in the CNM mass fraction of ∼70%. The velocity dispersion is limited to the thermal-instability-mediated level of ∼2-3 km s-1, and the layer is supported by both turbulent and thermal energy equally. We also propose an effective equation of state that models the multiphase ISM formed by the WNM converging flow as a one-phase ISM in the form of P ∝ ργeff, where γ eff varies from 0.9 (for a large pre-shock Δρ 0) to 0.7 (for a small pre-shock Δρ 0).

DOI： 10.3847/1538-4357/abc5be

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Formation and evolution of the local interstellar environment: combined constraints from nucleosynthetic and X-ray data Reviewed International coauthorship Open Access

Fujimoto, Y; Krumholz, MR; Inutsuka, S; Boss, AP; Nittler, LR

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 498 ( 4 ) page： 5532 - 5540   2020.11

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DOI： 10.1093/mnras/staa2778

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Unifying low- and high-mass star formation through density-amplified hubs of filaments The highest mass stars (&gt;100 <i>M</i>_⊙) form only in hubs? Reviewed International coauthorship Open Access

Kumar, MSN; Palmeirim, P; Arzoumanian, D; Inutsuka, SI

ASTRONOMY & ASTROPHYSICS   Vol. 642   2020.10

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Astronomy and Astrophysics  

Context. Star formation takes place in giant molecular clouds, resulting in mass-segregated young stellar clusters composed of Sun-like stars, brown dwarfs, and massive O-type(50-100 M) stars. Aims. We aim to identify candidate hub-filament systems (HFSs) in the Milky Way and examine their role in the formation of the highest mass stars and star clusters. Methods. The Herschel survey HiGAL has catalogued about 105 clumps. Of these, approximately 35 000 targets are detected at the 3σ level in a minimum of four bands. Using the DisPerSE algorithm we detect filamentary skeletons on 10′ × 10′ cut-outs of the SPIRE 250 μm images (18′′ beam width) of the targets. Any filament with a total length of at least 55′′ (3 × 18′′) and at least 18′′ inside the clump was considered to form a junction at the clump. A hub is defined as a junction of three or more filaments. Column density maps were masked by the filament skeletons and averaged for HFS and non-HFS samples to compute the radial profile along the filaments into the clumps. Results. Approximately 3700 (11%) are candidate HFSs, of which about 2150 (60%) are pre-stellar and 1400 (40%) are proto-stellar. The filaments constituting the HFSs have a mean length of ∼10-20 pc, a mass of ∼5 × 104 M, and line masses (M/L) of ∼2 × 103 M pc-1. All clumps with L > 104 L and L > 105 L at distances within 2 and 5 kpc respectively are located in the hubs of HFSs. The column densities of hubs are found to be enhanced by a factor of approximately two (pre-stellar sources) up to about ten (proto-stellar sources). Conclusions. All high-mass stars preferentially form in the density-enhanced hubs of HFSs. This amplification can drive the observed longitudinal flows along filaments providing further mass accretion. Radiation pressure and feedback can escape into the inter-filamentary voids. We propose a "filaments to clusters"unified paradigm for star formation, with the following salient features: (a) low-intermediate-mass stars form slowly (106 yr) in the filaments and massive stars form quickly (105 yr) in the hub, (b) the initial mass function is the sum of stars continuously created in the HFS with all massive stars formed in the hub, (c) feedback dissipation and mass segregation arise naturally due to HFS properties, and explain the (d) age spreads within bound clusters and the formation of isolated OB associations.

DOI： 10.1051/0004-6361/202038232

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ALMA CO Observations of Gamma-Ray Supernova Remnant N132D in the Large Magellanic Cloud: Possible Evidence for Shocked Molecular Clouds Illuminated by Cosmic-Ray Protons Reviewed International coauthorship Open Access

Sano, H; Plucinsky, PP; Bamba, A; Sharda, P; Filipovic, MD; Law, CJ; Alsaberi, RZE; Yamane, Y; Tokuda, K; Acero, F; Sasaki, M; Vink, J; Inoue, T; Inutsuka, S; Shimoda, J; Tsuge, K; Fujii, K; Voisin, F; Maxted, N; Rowell, G; Onishi, T; Kawamura, A; Mizuno, N; Yamamoto, H; Tachihara, K; Fukui, Y

ASTROPHYSICAL JOURNAL   Vol. 902 ( 1 )   2020.10

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

N132D is the brightest gamma-ray supernova remnant (SNR) in the Large Magellanic Cloud (LMC). We carried out 12CO(J = 1-0, 3-2) observations toward the SNR using the Atacama Large Millimeter/submillimeter Array (ALMA) and Atacama Submillimeter Telescope Experiment. We find diffuse CO emission not only at the southern edge of the SNR as previously known, but also inside the X-ray shell. We spatially resolved nine molecular clouds using ALMA with an angular resolution of 5″, corresponding to a spatial resolution of ∼1 pc at the distance of the LMC. Typical cloud sizes and masses are ∼2.0 pc and ∼100 M o˙, respectively. High intensity ratios of CO J = 3-2/1-0 > 1.5 are seen toward the molecular clouds, indicating that shock heating has occurred. Spatially resolved X-ray spectroscopy reveals that thermal X-rays in the center of N132D are produced not only behind a molecular cloud but also in front of it. Considering the absence of a thermal component associated with the forward shock toward one molecular cloud located along the line of sight to the center of the remnant, this suggests that this particular cloud is engulfed by shock waves and is positioned on the near side of the remnant. If the hadronic process is the dominant contributor to the gamma-ray emission, the shock-engulfed clouds play a role as targets for cosmic rays. We estimate the total energy of cosmic-ray protons accelerated in N132D to be ∼0.5-3.8 × 1049 erg as a conservative lower limit, which is similar to that observed in Galactic gamma-ray SNRs.

DOI： 10.3847/1538-4357/abb469

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Distribution and kinematics of <SUP>26</SUP>Al in the Galactic disc Reviewed International coauthorship Open Access

Fujimoto, Y; Krumholz, MR; Inutsuka, S

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 497 ( 2 ) page： 2442 - 2454   2020.9

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Monthly Notices of the Royal Astronomical Society  

26Al is a short-lived radioactive isotope thought to be injected into the interstellar medium (ISM) by massive stellar winds and supernovae (SNe). However, all-sky maps of 26Al emission show a distribution with a much larger scale height and faster rotation speed than either massive stars or the cold ISM. We investigate the origin of this discrepancy using an N-body + hydrodynamics simulation of a Milky-Way-like galaxy, self-consistently including self-gravity, star formation, stellar feedback, and 26Al production. We find no evidence that the Milky Way's spiral structure explains the 26Al anomaly. Stars and the 26Al bubbles they produce form along spiral arms, but, because our simulation produces material arms that arise spontaneously rather than propagating arms forced by an external potential, star formation occurs at arm centres rather than leading edges. As a result, we find a scale height and rotation speed for 26Al similar to that of the cold ISM. However, we also show that a synthetic 26Al emission map produced for a possible Solar position at the edge of a large 26Al bubble recovers many of the major qualitative features of the observed 26Al sky. This suggests that the observed anomalous 26Al distribution is the product of foreground emission from the 26Al produced by a nearby, recent SN.

DOI： 10.1093/mnras/staa2125

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Secular Gravitational Instability of Drifting Dust in Protoplanetary Disks: Formation of Dusty Rings without Significant Gas Substructures Reviewed Open Access

Tominaga, RT; Takahashi, SZ; Inutsuka, S

ASTROPHYSICAL JOURNAL   Vol. 900 ( 2 )   2020.9

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

Secular gravitational instability (GI) is one promising mechanism for creating annular substructures and planetesimals in protoplanetary disks. We perform numerical simulations of secular GI in a radially extended disk with inwardly drifting dust grains. The results show that, even in the presence of dust diffusion, dust rings form via secular GI while the dust grains are moving inward, and the dust surface density increases by a factor of 10. Once secular GI develops into a nonlinear regime, the total mass of the resultant rings can be a significant fraction of the dust disk mass. In this way, a large amount of drifting dust grains can be collected in the dusty rings and stored for planetesimal formation. In contrast to the emergence of remarkable dust substructures, secular GI does not create significant gas substructures. This result indicates that observations of a gas density profile near the disk midplane enable us to distinguish the mechanisms for creating the annular substructures in the observed disks. The resultant rings start decaying once they enter the inner region stable to secular GI. Because the ring-gap contrast smoothly decreases, it seems possible that the rings are observed even in the stable region. We also discuss the likely outcome of the nonlinear growth and indicate the possibility that a significantly developed region of secular GI may appear as a gap-like substructure in dust continuum emission as dust growth into larger solid bodies and planetesimal formation reduce the total emissivity.

DOI： 10.3847/1538-4357/abad36

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A Low-velocity Bipolar Outflow from a Deeply Embedded Object in Taurus Revealed by the Atacama Compact Array Reviewed International coauthorship Open Access

Fujishiro, K; Tokuda, K; Tachihara, K; Takashima, T; Fukui, Y; Zahorecz, S; Saigo, K; Matsumoto, T; Tomida, K; Machida, MN; Inutsuka, S; André, P; Kawamura, A; Onishi, T

ASTROPHYSICAL JOURNAL LETTERS   Vol. 899 ( 1 )   2020.8

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

The first hydrostatic core, the first quasi-hydrostatic object formed during the star formation process, is still the observational missing link between the prestellar and protostellar phases, mainly due to its short lifetime. Although we have not established a clear method to identify this rare object, recent theoretical studies predict that the first core has millimeter continuum emission and low-velocity outflow with a wide opening angle. An extensive continuum/outflow survey toward a large number of "starless"cores in nearby star-forming regions works as a pathfinder. We observed 32 prestellar cores in Taurus with an average density of ⪆105 cm-3 in 1.3 mm continuum and molecular lines using the Atacama Large Millimeter/submillimeter Array-Atacama Compact Array (ALMA-ACA) stand-alone mode. Among the targets, MC35-mm centered at one of the densest "starless"cores in Taurus has blueshifted/redshifted wings in the 12CO (2-1) line, indicating that there is a deeply embedded object driving molecular outflow. The observed velocities and sizes of the possible outflow lobes are 2-4 km s-1 and ∼2 × 103 au, respectively, and the dynamical time is calculated to be ∼103 yr. In addition to this, the core is one of the strongest N2D+ (3-2) emitters in our sample. All of the observed signatures do not conflict with any of the theoretical predictions about the first hydrostatic core so far, and thus MC35-mm is unique as the only first-core candidate in the Taurus molecular cloud.

DOI： 10.3847/2041-8213/ab9ca8

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FRagmentation and Evolution of Dense Cores Judged by ALMA (FREJA). I. Overview: Inner ∼1000 au Structures of Prestellar/Protostellar Cores in Taurus Reviewed International coauthorship Open Access

Tokuda, K; Fujishiro, K; Tachihara, K; Takashima, T; Fukui, Y; Zahorecz, S; Saigo, K; Matsumoto, T; Tomida, K; Machida, MN; Inutsuka, S; André, P; Kawamura, A; Onishi, T

ASTROPHYSICAL JOURNAL   Vol. 899 ( 1 )   2020.8

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

We have performed survey-type observations in 1 mm continuum and molecular lines toward dense cores (32 prestellar + 7 protostellar) with an average density of ⪆105 cm-3 in the Taurus molecular clouds using the Atacama Large Millimeter/submillimeter Array-Atacama Compact Array (ALMA-ACA) stand-alone mode with an angular resolution of 6.″5 (∼900 au). The primary purpose of this study is to investigate the innermost part of dense cores with view to understanding the initial condition of star formation. In the protostellar cores, contributions from protostellar disks dominate the observed continuum flux with a range of 35%-90%, except for the very low-luminosity object. For the prestellar cores, we have successfully confirmed continuum emission from dense gas with a density of ⪆3 × 105 cm-3 toward approximately one-third of the targets. Thanks to the lower spatial frequency coverage with the ACA 7 m array, the detection rate is significantly higher than that of the previous surveys, which have zero or one continuum-detected sources among a large number of starless samples using the ALMA Main Array. The statistical counting method tells us that the lifetime of prestellar cores until protostar formation therein approaches the freefall time as the density increases. Among the prestellar cores, at least two targets have possible internal substructures, which are detected in continuum emission with the size scale of ∼1000 au if we consider the molecular line (C18O and N2D+) distributions. These results suggest that small-scale fragmentation/coalescence processes occur in a region smaller than 0.1 pc, which may determine the final core mass associated with individual protostar formation before starting the dynamical collapse of the core with a central density of ∼(0.3-1) × 106 cm-3.

DOI： 10.3847/1538-4357/ab9ca7

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The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333 Reviewed International coauthorship Open Access

Doi, Y; Hasegawa, T; Furuya, RS; Coudé, S; Hull, CLH; Arzoumanian, D; Bastien, P; Chen, MCY; Di Francesco, J; Friesen, R; Houde, M; Inutsuka, SI; Mairs, S; Matsumura, M; Onaka, T; Sadavoy, S; Shimajiri, Y; Tahani, M; Tomisaka, K; Eswaraiah, C; Koch, PM; Pattle, K; Lee, CW; Tamura, M; Berry, D; Ching, TC; Hwang, J; Kwon, W; Soam, A; Wang, JW; Lai, SP; Qiu, K; Ward-Thompson, D; Byun, DY; Chen, HRV; Chen, WP; Chen, ZW; Cho, J; Choi, M; Choi, Y; Chrysostomou, A; Chung, EJ; Diep, PN; Duan, HY; Fanciullo, L; Fiege, J; Franzmann, E; Friberg, P; Fuller, G; Gledhill, T; Graves, SF; Greaves, JS; Griffin, MJ; Gu, QL; Han, I; Hatchell, J; Hayashi, SS; Hoang, T; Inoue, T; Iwasaki, K; Jeong, IG; Johnstone, D; Kanamori, Y; Kang, JH; Kang, M; Kang, SJ; Kataoka, A; Kawabata, KS; Kemper, F; Kim, G; Kim, J; Kim, KT; Kim, KH; Kim, MR; Kim, S; Kirk, JM; Kobayashi, MIN; Konyves, V; Kusune, T; Kwon, J; Lacaille, K; Law, CY; Lee, CF; Lee, H; Lee, JE; Lee, SS; Lee, YH; Li, DL; Li, D; Li, HB; Liu, HL; Liu, J; Liu, SY; Liu, T; de Looze, I; Lyo, AR; Matthews, BC; Moriarty-Schieven, GH; Nagata, T; Nakamura, F; Nakanishi, H; Ohashi, N; Park, G; Parsons, H; Peretto, N; Pyo, TS; Qian, L; Rao, R; Rawlings, MG; Retter, B; Richer, J; Rigby, A; Saito, H; Savini, G; Scaife, AMM; Seta, M; Shinnaga, H; Tang, YW; Tsukamoto, Y; Viti, S; Wang, HC; Whitworth, AP; 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. 899 ( 1 )   2020.8

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

We present new observations of the active star formation region NGC 1333 in the Perseus molecular cloud complex from the James Clerk Maxwell Telescope B-Fields In Star-forming Region Observations (BISTRO) survey with the POL-2 instrument. The BISTRO data cover the entire NGC 1333 complex (∼1.5 pc ? 2 pc) at 0.02 pc resolution and spatially resolve the polarized emission from individual filamentary structures for the first time. The inferred magnetic field structure is complex as a whole, with each individual filament aligned at different position angles relative to the local field orientation. We combine the BISTRO data with low- and high- resolution data derived from Planck and interferometers to study the multiscale magnetic field structure in this region. The magnetic field morphology drastically changes below a scale of ∼1 pc and remains continuous from the scales of filaments (∼0.1 pc) to that of protostellar envelopes (∼0.005 pc or ∼1000 au). Finally, we construct simple models in which we assume that the magnetic field is always perpendicular to the long axis of the filaments. We demonstrate that the observed variation of the relative orientation between the filament axes and the magnetic field angles are well reproduced by this model, taking into account the projection effects of the magnetic field and filaments relative to the plane of the sky. These projection effects may explain the apparent complexity of the magnetic field structure observed at the resolution of BISTRO data toward the filament network.

DOI： 10.3847/1538-4357/aba1e2

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The Origin of the Stellar Mass Distribution and Multiplicity Open Access

Lee, YN; Offner, SSR; Hennebelle, P; André, P; Zinnecker, H; Ballesteros-Paredes, J; Inutsuka, S; Kruijssen, JMD

SPACE SCIENCE REVIEWS   Vol. 216 ( 4 )   2020.6

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Language：Japanese   Publishing type：Research paper (international conference proceedings)   Publisher：Space Science Reviews  

In this chapter, we review some historical understanding and recent advances on the Initial Mass Function (IMF) and the Core Mass Function (CMF), both in terms of observations and theories. We focus mostly on star formation in clustered environment since this is suggested by observations to be the dominant mode of star formation. The statistical properties and the fragmentation behaviour of turbulent gas is discussed, and we also discuss the formation of binaries and small multiple systems.

DOI： 10.1007/s11214-020-00699-2

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