المؤلفون: Fengwei Xu, Ke Wang, Tie Liu, David Eden, Xunchuan Liu, Mika Juvela, Jinhua He, Doug Johnstone, Paul Goldsmith, Guido Garay, Yuefang Wu, Archana Soam, Alessio Traficante, Isabelle Ristorcelli, Edith Falgarone, Huei-Ru Vivien Chen, Naomi Hirano, Yasuo Doi, Woojin Kwon, Glenn J. White, Anthony Whitworth, Patricio Sanhueza, Mark G. Rawlings, Dana Alina, Zhiyuan Ren, Chang Won Lee, Ken’ichi Tatematsu, Chuan-Peng Zhang, Jianjun Zhou, Shih-Ping Lai, Derek Ward-Thompson, Sheng-Yuan Liu, Qilao Gu, Eswaraiah Chakali, Lei Zhu, Diego Mardones, L. Viktor Tóth

المصدر: The Astrophysical Journal Letters, Vol 963, Iss 1, p L9 (2024)

مصطلحات موضوعية: Star formation, Molecular clouds, High latitude field, Astrophysics, QB460-466

الوصف: High-latitude (∣ b ∣ > 30°) molecular clouds have virial parameters that exceed 1, but whether these clouds can form stars has not been studied systematically. Using JCMT SCUBA-2 archival data, we surveyed 70 fields that target high-latitude Planck Galactic cold clumps (HLPCs) to find dense cores with density of 10 ^5 –10 ^6 cm ^−3 and size of 1 × 10 ^21 cm ^−2 ). At an average rms of 15 mJy beam ^−1 , we detected Galactic dense cores in only one field, G6.04+36.77 (L183) while also identifying 12 extragalactic objects and two young stellar objects. Compared to the low-latitude clumps, dense cores are scarce in HLPCs. With synthetic observations, the densities of cores are constrained to be n _c ≲ 10 ^5 cm ^−3 should they exist in HLPCs. Low-latitude clumps, Taurus clumps, and HLPCs form a sequence where a higher virial parameter corresponds to a lower dense-core detection rate. If HLPCs were affected by the Local Bubble, the scarcity should favor turbulence-inhibited rather than supernova-driven star formation. Studies of the formation mechanism of the L183 molecular cloud are warranted.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2041-8205Test

الوصول الحر: https://doaj.org/article/8e3aa8d23bb6459c80060fd043424f16Test

المؤلفون: Jia-Wei Wang, Patrick M. Koch, Seamus D. Clarke, Gary Fuller, Nicolas Peretto, Ya-Wen Tang, Hsi-Wei Yen, Shih-Ping Lai, Nagayoshi Ohashi, Doris Arzoumanian, Doug Johnstone, Ray Furuya, Shu-ichiro Inutsuka, Chang Won Lee, Derek Ward-Thompson, Valentin J. M. Le Gouellec, Hong-Li Liu, Lapo Fanciullo, Jihye Hwang, Kate Pattle, Frédérick Poidevin, Mehrnoosh Tahani, Takashi Onaka, Mark G. Rawlings, Eun Jung Chung, Junhao Liu, A-Ran Lyo, Felix Priestley, Thiem Hoang, Motohide Tamura, David Berry, Pierre Bastien, Tao-Chung Ching, Simon Coudé, Woojin Kwon, Mike Chen, Chakali Eswaraiah, Archana Soam, Tetsuo Hasegawa, Keping Qiu, Tyler L. Bourke, Do-Young Byun, Zhiwei Chen, Huei-Ru Vivien Chen, Wen Ping Chen, Jungyeon Cho, Minho Choi, Yunhee Choi, Youngwoo Choi, Antonio Chrysostomou, Sophia Dai, James Di Francesco, Pham Ngoc Diep​, Yasuo Doi, Yan Duan, Hao-Yuan Duan, David Eden, Jason Fiege, Laura M. Fissel, Erica Franzmann, Per Friberg, Rachel Friesen, Tim Gledhill, Sarah Graves, Jane Greaves, Matt Griffin, Qilao Gu, Ilseung Han, Saeko Hayashi, Martin Houde, Tsuyoshi Inoue, Kazunari Iwasaki, Il-Gyo Jeong, Vera Könyves, Ji-hyun Kang, Miju Kang, Janik Karoly, Akimasa Kataoka, Koji Kawabata, Zacariyya Khan, Mi-Ryang Kim, Kee-Tae Kim, Kyoung Hee Kim, Shinyoung Kim, Jongsoo Kim, Hyosung Kim, Gwanjeong Kim, Florian Kirchschlager, Jason Kirk, Masato I. N. Kobayashi, Takayoshi Kusune, Jungmi Kwon, Kevin Lacaille, Chi-Yan Law, Sang-Sung Lee, Hyeseung Lee, Jeong-Eun Lee, Chin-Fei Lee, Dalei Li, Hua-bai Li, Guangxing Li, Di Li, Sheng-Jun Lin, Tie Liu, Sheng-Yuan Liu, Xing Lu, Steve Mairs, Masafumi Matsumura, Brenda Matthews, Gerald Moriarty-Schieven, Tetsuya Nagata, Fumitaka Nakamura, Hiroyuki Nakanishi, Nguyen Bich Ngoc, Geumsook Park, Harriet Parsons, Tae-Soo Pyo, Lei Qian, Ramprasad Rao, Jonathan Rawlings, Brendan Retter, John Richer, Andrew Rigby, Sarah Sadavoy, Hiro Saito, Giorgio Savini, Masumichi Seta, Ekta Sharma, Yoshito Shimajiri, Hiroko Shinnaga, Xindi Tang, Hoang Duc Thuong, Kohji Tomisaka, Le Ngoc Tram, Yusuke Tsukamoto, Serena Viti, Hongchi Wang, Anthony Whitworth, Jintai Wu, Jinjin Xie, Meng-Zhe Yang, Hyunju Yoo, Jinghua Yuan, Hyeong-Sik Yun, Tetsuya Zenko, Chuan-Peng Zhang, Yapeng Zhang, Guoyin Zhang, Jianjun Zhou, Lei Zhu, Ilse de Looze, Philippe André, C. Darren Dowell, Stewart Eyres, Sam Falle, Jean-François Robitaille, Sven van Loo

المصدر: The Astrophysical Journal, Vol 962, Iss 2, p 136 (2024)

مصطلحات موضوعية: Collapsing clouds, Interstellar filaments, Molecular clouds, Interstellar magnetic fields, Interstellar medium, Polarimetry, Astrophysics, QB460-466

الوصف: We report 850 μ m continuum polarization observations toward the filamentary high-mass star-forming region NGC 2264, taken as part of the B -fields In STar forming Regions Observations large program on the James Clerk Maxwell Telescope. These data reveal a well-structured nonuniform magnetic field in the NGC 2264C and 2264D regions with a prevailing orientation around 30° from north to east. Field strength estimates and a virial analysis of the major clumps indicate that NGC 2264C is globally dominated by gravity, while in 2264D, magnetic, gravitational, and kinetic energies are roughly balanced. We present an analysis scheme that utilizes the locally resolved magnetic field structures, together with the locally measured gravitational vector field and the extracted filamentary network. From this, we infer statistical trends showing that this network consists of two main groups of filaments oriented approximately perpendicular to one another. Additionally, gravity shows one dominating converging direction that is roughly perpendicular to one of the filament orientations, which is suggestive of mass accretion along this direction. Beyond these statistical trends, we identify two types of filaments. The type I filament is perpendicular to the magnetic field with local gravity transitioning from parallel to perpendicular to the magnetic field from the outside to the filament ridge. The type II filament is parallel to the magnetic field and local gravity. We interpret these two types of filaments as originating from the competition between radial collapsing, driven by filament self-gravity, and longitudinal collapsing, driven by the region's global gravity.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1538-4357Test

الوصول الحر: https://doaj.org/article/21ff8c4e532c407387cc018e418a7ecdTest

المؤلفون: Jin-Long Xu, Ming Zhu, Kelley M. Hess, Naiping Yu, Chuan-Peng Zhang, Xiao-Lan Liu, Mei Ai, Peng Jiang, Jie Wang

المصدر: The Astrophysical Journal Letters, Vol 958, Iss 2, p L31 (2023)

مصطلحات موضوعية: Galaxy evolution, Galaxy formation, Astrophysics, QB460-466

الوصف: Based on the atomic-hydrogen (H i ) observations using the Five-hundred-meter Aperture Spherical radio Telescope, we present a detailed study of the gas-rich massive S0 galaxy NGC 1023 in a nearby galaxy group. The presence of a H i extended warped disk in NGC 1023 indicates that this S0 galaxy originated from a spiral galaxy. The data also suggest that NGC 1023 is interacting with four dwarf galaxies. In particular, one of the largest dwarf galaxies has fallen into the gas disk of NGC 1023, forming a rare bright–dark galaxy pair with a large gas clump. This clump shows the signature of a galaxy but has no optical counterpart, implying that it is a newly formed starless galaxy. Our results first suggest that a massive S0 galaxy in a galaxy group can form via the morphological transformation from a spiral under the joint action of multiple tidal interactions.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2041-8205Test

الوصول الحر: https://doaj.org/article/4b62f5a0a48d483b8f256d4f051f63ffTest

المؤلفون: Jin-Long Xu, Ming Zhu, Naiping Yu, Chuan-Peng Zhang, Xiao-Lan Liu, Mei Ai, Peng Jiang

المصدر: The Astrophysical Journal Letters, Vol 944, Iss 2, p L40 (2023)

مصطلحات موضوعية: Extragalactic astronomy, Astrophysics, QB460-466

الوصف: Based on a new H i survey using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), combined with the Pan-STARRS1 images, we identified an isolated H i cloud without any optical counterpart, named FAST J0139+4328. The newly discovered H i cloud appears to be a typical disk galaxy since it has a double-peak shape in the global H i profile and an S-like rotation structure in the velocity-position diagram. Moreover, this disk galaxy has an extremely low absolute magnitude ( M _B > −10.0 mag) and stellar mass (

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2041-8205Test

الوصول الحر: https://doaj.org/article/6022fe3eb8bc470288c5c51d32456c5eTest

المؤلفون: Derek Ward-Thompson, Janik Karoly, Kate Pattle, Anthony Whitworth, Jason Kirk, David Berry, Pierre Bastien, Tao-Chung Ching, Simon Coudé, Jihye Hwang, Woojin Kwon, Archana Soam, Jia-Wei Wang, Tetsuo Hasegawa, Shih-Ping Lai, Keping Qiu, Doris Arzoumanian, Tyler L. Bourke, Do-Young Byun, Huei-Ru Vivien Chen, Wen Ping Chen, Mike Chen, Zhiwei Chen, Jungyeon Cho, Minho Choi, Youngwoo Choi, Yunhee Choi, Antonio Chrysostomou, Eun Jung Chung, Sophia Dai, Victor Debattista, James Di Francesco, Pham Ngoc Diep, Yasuo Doi, Hao-Yuan Duan, Yan Duan, Chakali Eswaraiah, Lapo Fanciullo, Jason Fiege, Laura M. Fissel, Erica Franzmann, Per Friberg, Rachel Friesen, Gary Fuller, Ray Furuya, Tim Gledhill, Sarah Graves, Jane Greaves, Matt Griffin, Qilao Gu, Ilseung Han, Saeko Hayashi, Thiem Hoang, Martin Houde, Charles L. H. Hull, Tsuyoshi Inoue, Shu-ichiro Inutsuka, Kazunari Iwasaki, Il-Gyo Jeong, Doug Johnstone, Vera Könyves, Ji-hyun Kang, Miju Kang, Akimasa Kataoka, Koji Kawabata, Francisca Kemper, Jongsoo Kim, Shinyoung Kim, Gwanjeong Kim, Kyoung Hee Kim, Mi-Ryang Kim, Kee-Tae Kim, Hyosung Kim, Florian Kirchschlager, Masato I. N. Kobayashi, Patrick M. Koch, Takayoshi Kusune, Jungmi Kwon, Kevin Lacaille, Chi-Yan Law, Chang Won Lee, Hyeseung Lee, Yong-Hee Lee, Chin-Fei Lee, Jeong-Eun Lee, Sang-Sung Lee, Dalei Li, Di Li, Guangxing Li, Hua-bai Li, Sheng-Jun Lin, Hong-Li Liu, Tie Liu, Sheng-Yuan Liu, Junhao Liu, Steven Longmore, Xing Lu, A-Ran Lyo, Steve Mairs, Masafumi Matsumura, Brenda Matthews, Gerald Moriarty-Schieven, Tetsuya Nagata, Fumitaka Nakamura, Hiroyuki Nakanishi, Nguyen Bich Ngoc, Nagayoshi Ohashi, Takashi Onaka, Geumsook Park, Harriet Parsons, Nicolas Peretto, Felix Priestley, Tae-Soo Pyo, Lei Qian, Ramprasad Rao, Jonathan Rawlings, Mark Rawlings, Brendan Retter, John Richer, Andrew Rigby, Sarah Sadavoy, Hiro Saito, Giorgio Savini, Masumichi Seta, Yoshito Shimajiri, Hiroko Shinnaga, Mehrnoosh Tahani, Motohide Tamura, Ya-Wen Tang, Xindi Tang, Kohji Tomisaka, Le Ngoc Tram, Yusuke Tsukamoto, Serena Viti, Hongchi Wang, Jintai Wu, Jinjin Xie, Meng-Zhe Yang, Hsi-Wei Yen, Hyunju Yoo, Jinghua Yuan, Hyeong-Sik Yun, Tetsuya Zenko, Guoyin Zhang, Yapeng Zhang, Chuan-Peng Zhang, Jianjun Zhou, Lei Zhu, Ilse de Looze, Philippe André, C. Darren Dowell, David Eden, Stewart Eyres, Sam Falle, Valentin J. M. Le Gouellec, Frédérick Poidevin, Jean-François Robitaille, Sven van Loo

المصدر: The Astrophysical Journal, Vol 946, Iss 2, p 62 (2023)

مصطلحات موضوعية: Interstellar magnetic fields, Molecular clouds, Starlight polarization, Collapsing clouds, Interstellar filaments, Astrophysics, QB460-466

الوصف: We present BISTRO Survey 850 μ m dust emission polarization observations of the L1495A-B10 region of the Taurus molecular cloud, taken at the James Clerk Maxwell Telescope (JCMT). We observe a roughly triangular network of dense filaments. We detect nine of the dense starless cores embedded within these filaments in polarization, finding that the plane-of-sky orientation of the core-scale magnetic field lies roughly perpendicular to the filaments in almost all cases. We also find that the large-scale magnetic field orientation measured by Planck is not correlated with any of the core or filament structures, except in the case of the lowest-density core. We propose a scenario for early prestellar evolution that is both an extension to, and consistent with, previous models, introducing an additional evolutionary transitional stage between field-dominated and matter-dominated evolution, observed here for the first time. In this scenario, the cloud collapses first to a sheet-like structure. Uniquely, we appear to be seeing this sheet almost face on. The sheet fragments into filaments, which in turn form cores. However, the material must reach a certain critical density before the evolution changes from being field dominated to being matter dominated. We measure the sheet surface density and the magnetic field strength at that transition for the first time and show consistency with an analytical prediction that had previously gone untested for over 50 yr.

العلاقة: https://doi.org/10.3847/1538-4357/acbea4Test; https://doaj.org/toc/1538-4357Test; https://doaj.org/article/4d2b3f17eafa430cbfabf53042703d14Test

الإتاحة: https://doi.org/10.3847/1538-4357/acbea4Test
https://doaj.org/article/4d2b3f17eafa430cbfabf53042703d14Test

المؤلفون: Janik Karoly, Derek Ward-Thompson, Kate Pattle, David Berry, Anthony Whitworth, Jason Kirk, Pierre Bastien, Tao-Chung Ching, Simon Coudé, Jihye Hwang, Woojin Kwon, Archana Soam, Jia-Wei Wang, Tetsuo Hasegawa, Shih-Ping Lai, Keping Qiu, Doris Arzoumanian, Tyler L. Bourke, Do-Young Byun, Huei-Ru Vivien Chen, Wen Ping Chen, Mike Chen, Zhiwei Chen, Jungyeon Cho, Minho Choi, Youngwoo Choi, Yunhee Choi, Antonio Chrysostomou, Eun Jung Chung, Sophia Dai, Victor Debattista, James Di Francesco, Pham Ngoc Diep, Yasuo Doi, Hao-Yuan Duan, Yan Duan, Chakali Eswaraiah, Lapo Fanciullo, Jason Fiege, Laura M. Fissel, Erica Franzmann, Per Friberg, Rachel Friesen, Gary Fuller, Ray Furuya, Tim Gledhill, Sarah Graves, Jane Greaves, Matt Griffin, Qilao Gu, Ilseung Han, Thiem Hoang, Martin Houde, Charles L. H. Hull, Tsuyoshi Inoue, Shu-ichiro Inutsuka, Kazunari Iwasaki, Il-Gyo Jeong, Doug Johnstone, Vera Könyves, Ji-hyun Kang, Miju Kang, Akimasa Kataoka, Koji Kawabata, Francisca Kemper, Jongsoo Kim, Shinyoung Kim, Gwanjeong Kim, Kyoung Hee Kim, Mi-Ryang Kim, Kee-Tae Kim, Hyosung Kim, Florian Kirchschlager, Masato I. N. Kobayashi, Patrick M. Koch, Takayoshi Kusune, Jungmi Kwon, Kevin Lacaille, Chi-Yan Law, Chang Won Lee, Hyeseung Lee, Yong-Hee Lee, Chin-Fei Lee, Jeong-Eun Lee, Sang-Sung Lee, Dalei Li, Di Li, Guangxing Li, Hua-bai Li, Sheng-Jun Lin, Hong-Li Liu, Tie Liu, Sheng-Yuan Liu, Junhao Liu, Steven Longmore, Xing Lu, A-Ran Lyo, Steve Mairs, Masafumi Matsumura, Brenda Matthews, Gerald Moriarty-Schieven, Tetsuya Nagata, Fumitaka Nakamura, Hiroyuki Nakanishi, Nguyen Bich Ngoc, Nagayoshi Ohashi, Takashi Onaka, Geumsook Park, Harriet Parsons, Nicolas Peretto, Felix Priestley, Tae-Soo Pyo, Lei Qian, Ramprasad Rao, Jonathan Rawlings, Mark Rawlings, Brendan Retter, John Richer, Andrew Rigby, Sarah Sadavoy, Hiro Saito, Giorgio Savini, Masumichi Seta, Ekta Sharma, Yoshito Shimajiri, Hiroko Shinnaga, Mehrnoosh Tahani, Motohide Tamura, Ya-Wen Tang, Xindi Tang, Kohji Tomisaka, Le Ngoc Tram, Yusuke Tsukamoto, Serena Viti, Hongchi Wang, Jintai Wu, Jinjin Xie, Meng-Zhe Yang, Hsi-Wei Yen, Hyunju Yoo, Jinghua Yuan, Hyeong-Sik Yun, Tetsuya Zenko, Guoyin Zhang, Yapeng Zhang, Chuan-Peng Zhang, Jianjun Zhou, Lei Zhu, Ilse de Looze, Philippe André, C. Darren Dowell, David Eden, Stewart Eyres, Sam Falle, Valentin J. M. Le Gouellec, Frédérick Poidevin, Jean-François Robitaille, Sven van Loo

المصدر: The Astrophysical Journal, Vol 952, Iss 1, p 29 (2023)

مصطلحات موضوعية: Stellar-interstellar interactions, Interstellar magnetic fields, Young stellar objects, Dust continuum emission, Starlight polarization, Molecular clouds, Astrophysics, QB460-466

الوصف: We present observations of polarized dust emission at 850 μ m from the L43 molecular cloud, which sits in the Ophiuchus cloud complex. The data were taken using SCUBA-2/POL-2 on the James Clerk Maxwell Telescope as a part of the BISTRO large program. L43 is a dense ( ${N}_{{{\rm{H}}}_{2}}\sim {10}^{22}$ –10 ^23 cm ^−2 ) complex molecular cloud with a submillimeter-bright starless core and two protostellar sources. There appears to be an evolutionary gradient along the isolated filament that L43 is embedded within, with the most evolved source closest to the Sco OB2 association. One of the protostars drives a CO outflow that has created a cavity to the southeast. We see a magnetic field that appears to be aligned with the cavity walls of the outflow, suggesting interaction with the outflow. We also find a magnetic field strength of up to ∼160 ± 30 μ G in the main starless core and up to ∼90 ± 40 μ G in the more diffuse, extended region. These field strengths give magnetically super- and subcritical values, respectively, and both are found to be roughly trans-Alfvénic. We also present a new method of data reduction for these denser but fainter objects like starless cores.

العلاقة: https://doi.org/10.3847/1538-4357/acd6f2Test; https://doaj.org/toc/1538-4357Test; https://doaj.org/article/f3411996bddc480fb76e84b95478be86Test

الإتاحة: https://doi.org/10.3847/1538-4357/acd6f2Test
https://doaj.org/article/f3411996bddc480fb76e84b95478be86Test

المؤلفون: Xu-Jia Ouyang, Yong Zhang, Albert Zijlstra, Chuan-Peng Zhang, Jun-ichi Nakashima, Quentin A. Parker

المصدر: The Astrophysical Journal, Vol 952, Iss 2, p 166 (2023)

مصطلحات موضوعية: Planetary nebulae, Single-dish antennas, Circumstellar envelopes, Stellar mass loss, Interstellar atomic gas, Astrophysics, QB460-466

الوصف: The young, compact, very high surface brightness but low excitation planetary nebula (PN) BD+30°3639 is one of the very few PNe that have been reported to exhibit the 21 cm H i emission line. As part of a long-term program to search for circumstellar atomic hydrogen, we observed the 21 cm feature toward BD+30°3639 with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Assuming a direct association between the PN and the detected H i emission, these new observations show that this surrounding emission is significantly more spatially extended than indicated by previous interferometric observations and can be resolved into two velocity components. The estimated H i mass is larger than 100 M _⊙ , invalidating an origin from the host star itself or its ejecta for the emitting material. We discuss the possibility that the extended H i emission stems from the interstellar medium (ISM) swept out over time by the stellar wind. Moreover, we report tentative detections of H i absorption features lying near and blueward of the systemic velocity of this PN, which are probably from a stalled asterosphere at the outer boundary of the expanding ionized region. The mass of the gas producing the H i absorption is insufficient to solve the so-called “PN missing mass problem.” We demonstrate the capability of FAST to investigate the interaction process between a PN and the surrounding ISM.

العلاقة: https://doi.org/10.3847/1538-4357/acd761Test; https://doaj.org/toc/1538-4357Test; https://doaj.org/article/607a621d232843d1ac4c1776b86a24daTest

الإتاحة: https://doi.org/10.3847/1538-4357/acd761Test
https://doaj.org/article/607a621d232843d1ac4c1776b86a24daTest

المؤلفون: Mehrnoosh Tahani, Pierre Bastien, Ray S. Furuya, Kate Pattle, Doug Johnstone, Doris Arzoumanian, Yasuo Doi, Tetsuo Hasegawa, Shu-ichiro Inutsuka, Simon Coudé, Laura Fissel, Michael Chun-Yuan Chen, Frédérick Poidevin, Sarah Sadavoy, Rachel Friesen, Patrick M. Koch, James Di Francesco, Gerald H. Moriarty-Schieven, Zhiwei Chen, Eun Jung Chung, Chakali Eswaraiah, Lapo Fanciullo, Tim Gledhill, Valentin J. M. Le Gouellec, Thiem Hoang, Jihye Hwang, Ji-hyun Kang, Kyoung Hee Kim, Florian Kirchschlager, Woojin Kwon, Chang Won Lee, Hong-Li Liu, Takashi Onaka, Mark G. Rawlings, Archana Soam, Motohide Tamura, Xindi Tang, Kohji Tomisaka, Anthony P. Whitworth, Jungmi Kwon, Thuong D. Hoang, Matt Redman, David Berry, Tao-Chung Ching, Jia-Wei Wang, Shih-Ping Lai, Keping Qiu, Derek Ward-Thompson, Martin Houde, Do-Young Byun, Huei-Ru Vivien Chen, Wen Ping Chen, Jungyeon Cho, Minho Choi, Yunhee Choi, Antonio Chrysostomou, Pham Ngoc Diep, Hao-Yuan Duan, Jason Fiege, Erica Franzmann, Per Friberg, Gary Fuller, Sarah F. Graves, Jane S. Greaves, Matt J. Griffin, Qilao Gu, Ilseung Han, Jennifer Hatchell, Saeko S. Hayashi, Charles L. H. Hull, Tsuyoshi Inoue, Kazunari Iwasaki, Il-Gyo Jeong, Yoshihiro Kanamori, Miju Kang, Sung-ju Kang, Akimasa Kataoka, Koji S. Kawabata, Francisca Kemper, Gwanjeong Kim, Jongsoo Kim, Kee-Tae Kim, Mi-Ryang Kim, Shinyoung Kim, Jason M. Kirk, Masato I. N. Kobayashi, Vera Konyves, Takayoshi Kusune, Kevin Lacaille, Chi-Yan Law, Chin-Fei Lee, Hyeseung Lee, Jeong-Eun Lee, Sang-Sung Lee, Yong-Hee Lee, Dalei Li, Di Li, Hua-bai Li, Junhao Liu, Sheng-Yuan Liu, Tie Liu, Ilse de Looze, A-Ran Lyo, Steve Mairs, Masafumi Matsumura, Brenda C. Matthews, Tetsuya Nagata, Fumitaka Nakamura, Hiroyuki Nakanishi, Nagayoshi Ohashi, Geumsook Park, Harriet Parsons, Nicolas Peretto, Tae-Soo Pyo, Lei Qian, Ramprasad Rao, Brendan Retter, John Richer, Andrew Rigby, Hiro Saito, Giorgio Savini, Anna M. M. Scaife, Masumichi Seta, Yoshito Shimajiri, Hiroko Shinnaga, Ya-Wen Tang, Yusuke Tsukamoto, Serena Viti, Hongchi Wang, Hsi-Wei Yen, Hyunju Yoo, Jinghua Yuan, Hyeong-Sik Yun, Tetsuya Zenko, Chuan-Peng Zhang, Guoyin Zhang, Yapeng Zhang, Jianjun Zhou, Lei Zhu, Philippe André, C. Darren Dowell, Stewart P. S. Eyres, Sam Falle, Sven van Loo, Jean-François Robitaille

المصدر: The Astrophysical Journal, Vol 944, Iss 2, p 139 (2023)

مصطلحات موضوعية: H II regions, Interstellar magnetic fields, Star formation, Molecular clouds, Dust continuum emission, Astrophysics, QB460-466

الوصف: We study the H ii 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 H ii 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 H ii 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.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1538-4357Test

الوصول الحر: https://doaj.org/article/6cc536dc64474f63ab58f4168f988160Test

المؤلفون: Nai-Ping Yu, Ming Zhu, Jin-Long Xu, Chuan-Peng Zhang, Xiao-Lan Liu, Peng Jiang, Jun-Jie Wang

المصدر: Monthly Notices of the Royal Astronomical Society. 521:737-742

مصطلحات موضوعية: Space and Planetary Science, Astronomy and Astrophysics

الوصف: With the aim to study the extended H i environment around dwarf galaxies in the local universe, we performed a high-sensitivity H i observation of the DDO 168 and DDO 167 pair using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). We chose this pair as previous studies indicate that DDO 168 might have undergone an interaction with a local companion. Based on this deep observation, no new extra gas was found around DDO 167 and it was hardly resolved by FAST. On the other hand, on the north side of DDO 168 we discovered an extended plume of H i gas which has never been detected before. The plume has a ring-like structure with a radius of about 5.0 kpc and its gas mass is estimated to be 5.2 × 107 M⊙. The expanding velocity of the plume is about 30 km s−1, corresponding to a dynamical age of about 200 Myr. The position–velocity (PV) diagrams cut through the two galaxies show a short and pronounced ‘spur’ pointing to DDO 167 from DDO 168, indicating a tidal interaction between the two galaxies. We also found an H i knot in the plume. The gas mass of the knot is about 9.5 × 106 M⊙. This value is much higher than its virial mass, indicating the knot is gravitationally unstable and star formation will take place there in the future. Our study suggests that the ring-like structure of the plume might be caused by the passage of DDO 167 through the outer disc of DDO 168 about 200 Myr ago. We also discussed other plausible scenarios for the origin of the plume.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::4ecd82ec16528244fec6c316af87e97bTest
https://doi.org/10.1093/mnras/stad561Test

المؤلفون: Jin-Long Xu, Ming ZHU, Peng Jiang, Naiping Yu, Chuan-Peng Zhang, Xiao-Lan Liu, Jie Wang

الوصف: One of the puzzles in extragalactic astronomy is the number disparity between the standard cold dark matter (CDM) predictions of low-mass dwarf galaxy and observations. It is often referred to as the missing satellite problem. With a large amount of deep optical surveys, the disparity has considerably decreased, but such problem remains open. The existence of ``dark galaxies", being gas-rich but nearly starless, can offers a standard way to explain the missing satellite problem. To date, many objects are considered as candidates of the dark galaxies, however, none of the candidates can be confirmed with solid evidence. Here we report the discovery of an optically bright-dark binary galaxy in the hub position of a filament in nearby galaxy group NGC 1023, based on HI observation using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The optically bright member of this binary is the known dwarf galaxy NGC 1023A, while the other member is a newly detected dark galaxy FAST 0240+3905. Besides, the binary galaxy shows a Keplerian rotation, implying that two members of the binary is merging. Our result suggests that even if dark galaxies exist, they can merge with other nearby galaxies in a short time scale. Being merged could provide another important clues to the missing satellite problem.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::8d6258cf62b3985b3cf6a63b0a660c16Test
https://doi.org/10.21203/rs.3.rs-1859764/v1Test