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arXiv 2023年

作者： Tanaka, Masaomi Domoto, Nanae Aoki, Wako Ishigaki, Miho N. Wanajo, Shinya Hotokezaka, Kenta Kawaguchi, Kyohei Kato, Daiji Lee, Jae-Joon Lee, Ho-Gyu Hirano, Teruyuki Kotani, Takayuki Kuzuhara, Masayuki Nishikawa, Jun Omiya, Masashi Tamura, Motohide Ueda, Akitoshi Astronomical Institute Tohoku University Aoba Sendai980-8578 Japan Division for the Establishment of Frontier Sciences Organization for Advanced Studies Tohoku University Sendai980-8577 Japan National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Astronomical Science Program The Graduate University for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Am Mühlenberg 1 Potsdam-GolmD-14476 Germany Research Center for the Early Universe Graduate School of Science University of Tokyo Bunkyo Tokyo113-0033 Japan UTIAS The University of Tokyo Chiba Kashiwa277-8583 Japan Institute for Cosmic Ray Research The University of Tokyo Chiba Kashiwa277-8582 Japan Center for Gravitational Physics Yukawa Institute for Theoretical Physics Kyoto University Kyoto606-8502 Japan National Institute for Fusion Science 322-6 Oroshi-cho Toki509-5292 Japan Interdisciplinary Graduate School of Engineering Sciences Kyushu University Fukuoka Kasuga816-8580 Japan Korea Astronomy and Space Science Institute 776 Daedeok-daero Yuseong-gu Daejeon34055 Korea Republic of Space Policy Research Center Science and Technology Policy Institute 370 Sicheong-daero Sejong30147 Korea Republic of Astrobiology Center 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan

Observations of the kilonova from a neutron star merger event GW170817 opened a way to directly study r-process nucleosynthesis by neutron star mergers. It is, however, challenging to identify the individual elements in the kilonova spectra due to lack of complete atomic data, in particular, at near-infrared wavelengths. In this paper, we demonstrate that spectra of chemically peculiar stars with enhanced heavy element abundances can provide us with an excellent astrophysical laboratory for kilonova spectra. We show that the photosphere of a late B-type chemically peculiar star HR 465 has similar lanthanide abundances and ionization degrees with those in the line forming region in a kilonova at ∼ 2.5 days after the merger. The near-infrared spectrum of HR 465 taken with Subaru/IRD indicates that Ce III lines give the strongest absorption features around 16,000 Å and there are no other comparably strong transitions around these lines. The Ce III lines nicely match with the broad absorption features at 14,500 Å observed in GW170817 with a blueshift of v = 0.1c, which supports recent identification of this feature as Ce III by Domoto et al. (2022). © 2023, CC BY.

关键词： Absorption spectroscopy

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programmable time-domain digital-coding metasurface for non-linear harmonic manipulation and new wireless communication systems

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National science Review 2019年第2期6卷 231-238页

作者： Jie Zhao Xi Yang Jun Yan Dai Qiang Cheng Xiang Li Ning Hua Qi Jun Chen Ke Guo Dong Bai Shuo Liu Shi Jin Andrea Alù Tie Jun Cui State Key Laboratory of Millimeter Waves Southeast University National Mobile Communication Research Laboratory Southeast University Synergetic Innovation Center of Wireless Communication Technology Southeast University Photonics Initiative Advanced Science Research Center City University of New York Physics Program The Graduate Center City University of New York Department of Electrical Engineering City College of New York Jiangsu Cyber-Space Science & Technology Co. Ltd

Optical non-linear phenomena are typically observed in natural materials interacting with light at high intensities, and they benefit a diverse range of applications from communication to sensing. However,controlling harmonic conversion with high efficiency and flexibility remains a major issue in modern optical and radio-frequency systems. Here, we introduce a dynamic time-domain digital-coding metasurface that enables efficient manipulation of spectral harmonic distribution. By dynamically modulating the local phase of the surface reflectivity, we achieve accurate control of different harmonics in a highly programmable and dynamic fashion, enabling unusual responses, such as velocity illusion. As a relevant application, we propose and realize a novel architecture for wireless communication systems based on the time-domain digital-coding metasurface, which largely simplifies the architecture of modern communication systems, at the same time yielding excellent performance for real-time signal transmission. The presented work, from new concept to new system, opens new pathways in the application of metamaterials to practical technology.

关键词： metasurface time-domain digital coding non-linear harmonics control new architecture of communication

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The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites

arXiv

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arXiv 2024年

作者： Spitzer, Fridolin Kleine, Thorsten Burkhardt, Christoph Hopp, Timo Yokoyama, Tetsuya Abe, Yoshinari Aléon, Jérôme OD. Alexander, Conel M. Amari, Sachiko Amelin, Yuri Bajo, Ken-Ichi Bizzarro, Martin Bouvier, Audrey Carlson, Richard W. Chaussidon, Marc Choi, Byeon-Gak Dauphas, Nicolas Davis, Andrew M. Rocco, Tommaso Di Fujiya, Wataru Fukai, Ryota Gautam, Ikshu Haba, Makiko K. Hibiya, Yuki Hidaka, Hiroshi Homma, Hisashi Hoppe, Peter Huss, Gary R. Ichida, Kiyohiro Iizuka, Tsuyoshi Ireland, Trevor R. Ishikawa, Akira Itoh, Shoichi Kawasaki, Noriyuki Kita, Noriko T. Kitajima, Kouki Komatani, Shintaro Krot, Alexander N. Liu, Ming-Chang Masuda, Yuki Morita, Mayu Moynier, Fréderic Motomura, Kazuko Nakai, Izumi Nagashima, Kazuhide Nguyen, Ann Nittler, Larry Onose, Morihiko Pack, Andreas Park, Changkun Piani, Laurette Qin, Liping Russell, Sara S. Sakamoto, Naoya Schönbächler, Maria Tafla, Lauren Tang, Haolan Terada, Kentaro Terada, Yasuko Usui, Tomohiro Wada, Sohei Wadhwa, Meenakshi Walker, Richard J. Yamashita, Katsuyuki Yin, Qing-Zhu Yoneda, Shigekazu Young, Edward D. Yui, Hiroharu Zhang, Ai-Cheng Nakamura, Tomoki Naraoka, Hiroshi Noguchi, Takaaki Okazaki, Ryuji Sakamoto, Kanako Yabuta, Hikaru Abe, Masanao Miyazaki, Akiko Nakato, Aiko Nishimura, Masahiro Okada, Tatsuaki Yada, Toru Yogata, Kasumi Nakazawa, Satoru Saiki, Takanao Tanaka, Satoshi Terui, Fuyuto Tsuda, Yuichi Watanabe, Sei-Ichiro Yoshikawa, Makoto Tachibana, Shogo Yurimoto, Hisayoshi Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany Department of Earth and Planetary Sciences Tokyo Institute of Technology Tokyo152-8551 Japan Graduate School of Engineering Materials Science and Engineering Tokyo Denki University Tokyo120-8551 Japan Institut de Minéralogie de Physique des Matériaux et de Cosmochimie Sorbonne Université Museum National d'Histoire Naturelle CNRS UMR 7590 IRD Paris75005 France Earth and Planets Laboratory Carnegie Institution for Science WashingtonDC20015 United States McDonnell Center for the Space Sciences and Physics Department Washington University 35 St. LouisMO63130 United States Geochemical Research Center The University of Tokyo Tokyo113-0033 Japan Guangzhou Institute of Geochemistry Chinese Academy of Sciences GD Guangzhou510640 China Departement of Natural History Sciences Hokkaido University Sapporo001-0021 Japan Centre for Star and Planet Formation Globe Institute University of Copenhagen Copenhagen1350 Denmark Bayerisches Geoinstitut Universität Bayreuth Bayreuth95447 Germany Université Paris Cité Institut de Physique du Globe de Paris CNRS Paris75005 France Department of Earth Science Education Seoul National University Seoul08826 Korea Republic of Department of the Geophysical Sciences Enrico Fermi Institute The University of Chicago 5734 South Ellis Avenue Chicago60637 United States Faculty of Geosciences and Geography University of Göttingen GöttingenD-37077 Germany Faculty of Science Ibaraki University Mito310-8512 Japan ISAS/JSEC JAXA Sagamihara252-5210 Japan Research Center for Advanced Science and Technology The University of Tokyo Tokyo153-8904 Japan Research Institute for Marine Resources Utilization Japan Agency for Marine-Earth Science and Technology Kanagawa237-0061 Japan Departement of Earth and Planetary Sciences Nagoya University Nagoya464-8601 Japan Osaka Application Laboratory SBUWDX Rigaku Corporation Osaka569-1

The isotopic compositions of samples returned from Cb-type asteroid Ryugu and Ivuna-type (CI) chondrites are distinct from other carbonaceous chondrites, which has led to the suggestion that Ryugu/CI chondrites formed in a different region of the accretion disk, possibly around the orbits of Uranus and Neptune. We show that, like for Fe, Ryugu and CI chondrites also have indistinguishable Ni isotope anomalies, which differ from those of other carbonaceous chondrites. We propose that this unique Fe and Ni isotopic composition reflects different accretion efficiencies of small FeNi metal grains among the carbonaceous chondrite parent bodies. The CI chondrites incorporated these grains more efficiently, possibly because they formed at the end of the disk’s lifetime, when planetesimal formation was also triggered by photoevaporation of the disk. Isotopic variations among carbonaceous chondrites may thus reflect fractionation of distinct dust components from a common reservoir, implying CI chondrites/Ryugu may have formed in the same region of the accretion disk as other carbonaceous chondrites. © 2024, CC BY.

关键词： Nickel

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The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). X. Hot Gas Reveals Deeply Embedded Star Formation

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Astrophysical Journal 2024年第2期963卷 163-163页

作者： Izumi, Natsuko Sanhueza, Patricio Koch, Patrick M. Lu, Xing Li, Shanghuo Sabatini, Giovanni Olguin, Fernando A. Zhang, Qizhou Nakamura, Fumitaka Tatematsu, Ken’ichi Morii, Kaho Sakai, Takeshi Tafoya, Daniel Institute of Astronomy and Astrophysics Academia Sinica No. 1 Section 2 Roosevelt Road Taipei 10617 Taiwan National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo 181-8588 Japan Astronomical Science Program The Graduate University for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo 181-8588 Japan Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai 200030 China Max Planck Institute for Astronomy Konigstuhl 17 Heidelberg D-69117 Germany INAF Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 Firenze I-50125 Italy Institute of Astronomy National Tsing Hua University Hsinchu 30013 Taiwan Center for Astrophysics Harvard & Smithsonian 60 Garden Street Cambridge 02138 MA United States Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan Graduate School of Informatics and Engineering The University of Electro-Communications Chofu Tokyo 182-8585 Japan Department of Space Earth and Environment Chalmers University of Technology Onsala Space Observatory Onsala SE-439 92 Sweden

Massive infrared dark clouds (IRDCs) are considered to host the earliest stages of high-mass star formation. In particular, 70 μm dark IRDCs are the colder and more quiescent clouds. At a scale of about 5000 au using formaldehyde (H₂CO) emission, we investigate the kinetic temperature of dense cores in 12 IRDCs obtained from the pilot Atacama Large Millimeter/submillimeter Array Survey of 70 μm dark High-mass clumps in Early Stages (ASHES). Compared to the 1.3 mm dust continuum and other molecular lines, such as C¹⁸O and deuterated species, we find that H₂CO is mainly sensitive to low-velocity outflow components rather than to quiescent gas expected in the early phases of star formation. The kinetic temperatures of these components range from 26 to 300 K. The Mach number reaches about 15 with an average value of about 4, suggesting that the velocity distribution of gas traced by H₂CO is significantly influenced by a supersonic nonthermal component. In addition, we detect warm line emission from HC₃N and OCS in 14 protostellar cores, which requires high excitation temperatures (E _u/k ∼ 100 K). These results show that some of the embedded cores in the ASHES fields are in an advanced evolutionary stage, previously unexpected for 70 μm dark IRDCs. © 2024. The Author(s). Published by the American Astronomical Society.

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The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). XI. Statistical Study of Early Fragmentation

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Astrophysical Journal 2024年第2期966卷 171-171页

作者： Morii, Kaho Sanhueza, Patricio Zhang, Qizhou Nakamura, Fumitaka Li, Shanghuo Sabatini, Giovanni Olguin, Fernando A. Beuther, Henrik Tafoya, Daniel Izumi, Natsuko Tatematsu, Ken’ichi Sakai, Takeshi Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo 181-8588 Japan Astronomical Science Program Graduate Institute for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo 181-8588 Japan Center for Astrophysics Harvard & Smithsonian 60 Garden Street Cambridge 02138 MA United States Max Planck Institute for Astronomy Königstuhl 17 Heidelberg D-69117 Germany INAF-Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 Firenze I-50125 Italy Institute of Astronomy National Tsing Hua University Hsinchu 30013 Taiwan Department of Space Earth and Environment Chalmers University of Technology Onsala Space Observatory Onsala 439 92 Sweden Academia Sinica Institute of Astronomy and Astrophysics 11F of AS/NTU Astronomy-Mathematics Building No.1 Section 4 Roosevelt Road Taipei 10617 Taiwan Graduate School of Informatics and Engineering The University of Electro-Communications Chofu Tokyo 182-8585 Japan

Fragmentation during the early stages of high-mass star formation is crucial for understanding the formation of high-mass clusters. We investigated fragmentation within 39 high-mass star-forming clumps as part of the Atacama Large Millimeter/submillimeter Array Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES) survey. Considering projection effects, we have estimated core separations for 839 cores identified from the continuum emission and found mean values between 0.08 and 0.32 pc within each clump. We find compatibility of the observed core separations and masses with the thermal Jeans length and mass, respectively. We also present subclump structures revealed by the 7 m array continuum emission. Comparison of the Jeans parameters using clump and subclump densities with the separation and masses of gravitationally bound cores suggests that they can be explained by clump fragmentation, implying the simultaneous formation of subclumps and cores within rather than a step-by-step hierarchical fragmentation. The number of cores in each clump positively correlates with the clump surface density and the number expected from the thermal Jeans fragmentation. We also find that the higher the fraction of protostellar cores, the larger the dynamic range of the core mass, implying that the cores are growing in mass as the clump evolves. The ASHES sample exhibits various fragmentation patterns: aligned, scattered, clustered, and subclustered. Using the Q -parameter, which can help distinguish between centrally condensed and subclustered spatial core distributions, we finally find that in the early evolutionary stages of high-mass star formation, cores tend to follow a subclustered distribution. © 2024. The Author(s). Published by the American Astronomical Society.

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The ALMA Survey of 70 µm Dark High-mass Clumps in Early Stages (ASHES). X: Hot Gas Reveals Deeply Embedded Star Formation

arXiv

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arXiv 2023年

作者： Izumi, Natsuko Sanhueza, Patricio Koch, Patrick M. Lu, Xing Li, Shanghuo Sabatini, Giovanni Olguin, Fernando A. Zhang, Qizhou Nakamura, Fumitaka Tatematsu, Ken'ichi Morii, Kaho Sakai, Takeshi Tafoya, Daniel Institute of Astronomy and Astrophysics Academia Sinica No. 1 Section 4 Roosevelt Road Taipei10617 Taiwan National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Astronomical Science Program The Graduate University for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Max Planck Institute for Astronomy Konigstuhl 17 HeidelbergD-69117 Germany INAF Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 FirenzeI-50125 Italy Institute of Astronomy National Tsing Hua University Hsinchu30013 Taiwan Center for Astrophysics |Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Department of Astronomy Graduate School of Science The University of Tokyo Bunkyo-ku Tokyo113-0033 Japan Graduate School of Informatics and Engineering The University of Electro-Communications Chofu Tokyo182-8585 Japan Department of Space Earth and Environment Chalmers University of Technology Onsala Space Observatory OnsalaSE-439 92 Sweden

Massive infrared dark clouds (IRDCs) are considered to host the earliest stages of high-mass star formation. In particular, 70 µm dark IRDCs are the colder and more quiescent clouds. At a scale of about 5000 au using formaldehyde (H2CO) emission, we investigate the kinetic temperature of dense cores in 12 IRDCs obtained from the pilot ALMA Survey of 70 µm dark High-mass clumps in Early Stages (ASHES). Compared to 1.3 mm dust continuum and other molecular lines, such as C18O and deuterated species, we find that H2CO is mainly sensitive to low-velocity outflow components rather than to quiescent gas expected in the early phases of star formation. The kinetic temperatures of these components range from 26 to 300 K. The Mach number reaches about 15 with an average value of about 4, suggesting that the velocity distribution of gas traced by H2CO is significantly influenced by a supersonic non-thermal component. In addition, we detect warm line emission from HC3N and OCS in 14 protostellar cores, which requires high excitation temperatures (Eu/k ∼ 100 K). These results show that some of the embedded cores in the ASHES fields are in an advanced evolutionary stage, previously unexpected for 70 µm dark IRDCs. Copyright © 2023, The Authors. All rights reserved.

关键词： Giant stars

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Experimentally shock-induced melt veins in basalt: Improving the shock classification of eucrites

arXiv

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arXiv 2022年

作者： Ono, Haruka Kurosawa, Kosuke Niihara, Takafumi Mikouchi, Takashi Tomioka, Naotaka Isa, Junko Kagi, Hiroyuki Matsuzaki, Takuya Sakuma, Hiroshi Genda, Hidenori Sakaiya, Tatsuhiro Kondo, Tadashi Kayama, Masahiro Koike, Mizuho Sano, Yuji Murayama, Masafumi Satake, Wataru Matsui, Takafumi Planetary Exploration Research Center Chiba Institute of Technology 2-17-1 Tsudanuma Narashino Chiba275-0016 Japan Department of Applied Science Okayama University of Science 1-1 Ridaicho Kita-ku Okayama-shi700-0005 Japan The University Museum The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan 200 Monobe Otsu Kochi Nankoku783-8502 Japan Geochemical Research Center Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan Center for Advanced Marine Core Research Kochi University 200 Monobe Otsu Kochi Nankoku783-8502 Japan Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Ibaraki Tsukuba305-0044 Japan Earth–Life Science Institute Tokyo Institute of Technology 2-12-1 Ookayama Meguro-ku Tokyo152-8550 Japan Department of Earth and Space Science Graduate School of Science Osaka University 1-1 Machikaneyama Osaka Toyonaka560-0043 Japan Department of General Systems Studies Graduate School of Arts and Sciences The Univ. of Tokyo 3-8-1 Komaba Meguro-ku Tokyo153-8902 Japan Earth and Planetary Systems Science Program Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashi–Hiroshima Hiroshima739-8526 Japan Institute of Geo-Cosmology Chiba Institute of Technology 2-17-1 Tsudanuma Chiba Narashino275-0016 Japan

Basaltic rocks occur widely on the terrestrial planets and differentiated asteroids, including the asteroid 4 Vesta. We conducted a shock recovery experiment with decaying compressive pulses on a terrestrial basalt at Chiba Institute of technology, Japan. The sample recorded a range of pressures, and shock physics modeling was conducted to add a pressure scale to the observed shock features. The shocked sample was examined by optical and electron microscopy, electron back-scattered diffractometry, and Raman spectroscopy. We found that localized melting occurs at a lower pressure (~10 GPa) than previously thought (>20 GPa). The shocked basalt near the epicenter represents "shock degree C" of a recently proposed classification scheme for basaltic eucrites and, as such, our results provide a pressure scale for the classification scheme. Finally, we estimated the total fraction of the basaltic eucrites classified as shock degree C to be ~15% by assuming the impact velocity distribution onto Vesta. © 2022, CC BY-NC-SA.

关键词： Basalt

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Intermediate-luminosity Type IIP SN 2021gmj: a low-energy explosion with signatures of circumstellar material

arXiv

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arXiv 2024年

作者： Murai, Yuta Tanaka, Masaomi Kawabata, Miho Taguchi, Kenta Teja, Rishabh Singh Nakaoka, Tatsuya Maeda, Keiichi Kawabata, Koji S. Nagao, Takashi Moriya, Takashi J. Sahu, D.K. Anupama, G.C. Tominaga, Nozomu Morokuma, Tomoki Imazawa, Ryo Inutsuka, Satoko Isogai, Keisuke Kasuga, Toshihiro Kobayashi, Naoto Kondo, Sohei Maehara, Hiroyuki Mori, Yuki Niino, Yuu Ogawa, Mao Ohsawa, Ryou Okumura, Shin-Ichiro Saito, Sei Sako, Shigeyuki Takahashi, Hidenori Uno, Kohki Yamanaka, Masayuki Astronomical Institute Tohoku University Sendai980-8578 Japan Division for the Establishment of Frontier Sciences Organization for Advanced Studies Tohoku University Sendai980-8577 Japan Nishi-Harima Astronomical Observatory Center for Astronomy University of Hyogo 407-2 Nishigaichi Sayo-cho Hyogo Sayo679-5313 Japan Department of Astronomy Kyoto University Kitashirakawa-Oiwake-cho Sakyo-ku Kyoto606-8502 Japan Indian Institute of Astrophysics Koramangala 2nd Block Bangalore560034 India Pondicherry University Chinna Kalapet Kalapet Puducherry605014 India Hiroshima Astrophysical Science Centre Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Department of Physics Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Department of Physics and Astronomy University of Turku TurkuFI-20014 Finland Aalto University Metsähovi Radio Observatory Metsähovintie 114 Kylmälä02540 Finland Aalto University Department of Electronics and Nanoengineering P.O. BOX 15500 AaltoFI-00076 Finland National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo181-8588 Japan School of Physics and Astronomy Faculty of Science Monash University ClaytonVIC3800 Australia Astronomical Science Program Graduate Institute for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Physics Faculty of Science and Engineering Konan University 8-9-1 Okamoto Hyogo Kobe658-8501 Japan The University of Tokyo 5-1-5 Kashiwanoha Chiba Kashiwa277-8583 Japan Planetary Exploration Research Center Chiba Institute of Technology 2-17-1 Tsudanuma Chiba Narashino275-0016 Japan Institute of Astronomy Graduate School of Science The University of Tokyo 2-21-1 Osawa Mitaka Tokyo181-0015 Japan Okayama Observatory Kyoto University 3037-5 Honjo Kamogatacho Okayama Asakuchi719-0232 Japan Dep

We present photometric, spectroscopic and polarimetric observations of the intermediate-luminosity Type IIP supernova (SN) 2021gmj from 1 to 386 days after the explosion. The peak absolute V-band magnitude of SN 2021gmj is −15.5 mag, which is fainter than that of normal Type IIP SNe. The spectral evolution of SN 2021gmj resembles that of other sub-luminous supernovae: the optical spectra show narrow P-Cygni profiles, indicating a low expansion velocity. We estimate the progenitor mass to be about 12 M☉ from the nebular spectrum and the 56Ni mass to be about 0.02 M☉ from the bolometric light curve. We also derive the explosion energy to be about 3×1050 erg by comparing numerical light curve models with the observed light curves. Polarization in the plateau phase is not very large, suggesting nearly spherical outer envelope. The early photometric observations capture the rapid rise of the light curve, which is likely due to the interaction with a circumstellar material (CSM). The broad emission feature formed by highly-ionized lines on top of a blue continuum in the earliest spectrum gives further indication of the CSM at the vicinity of the progenitor. Our work suggests that a relatively low-mass progenitor of an intermediate-luminosity Type IIP SN can also experience an enhanced mass loss just before the explosion, as suggested for normal Type IIP SNe. © 2024, CC BY.

关键词： Supernovae

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The Process We Call Earth: Relationships Between Dynamic Feedbacks and the Search for Gaiasignatures in a New Paradigm of Earthlikeness

Perspectives of Earth and Space Scientists

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Perspectives of Earth and space Scientists 2024年第1期5卷

作者： Michael L. Wong Marissa Duckett Emilia S. Hernandez Vahab Rajaei Kayla J. Smith Earth and Planets Laboratory Carnegie Institution for Science Washington DC USA NASA Hubble Fellowship Program Space Telescope Science Institute Baltimore MD USA M. L. Wong Population Biology Ecology and Evolution Graduate Program Graduate Division of Biological & Biomedical Sciences Emory University Atlanta GA USA Department of Earth and Planetary Sciences University of California Davis Davis CA USA Alaska Center for Energy and Power University of Alaska Fairbanks Fairbanks AK USA School of Chemistry and Biochemistry Georgia Institute of Technology Atlanta GA USA NASA Center for the Origins of Life Georgia Institute of Technology Atlanta GA USA Environmental Engineering Program Department of Water Resources Management Central State University Wilberforce OH USA

Standard notions of an “Earthlike” planet rely solely on physical and material properties, like planetary mass, radius, and surface temperature. Here, we introduce a novel, relational perspective on what defines “Earthlikeness.” In our process-based framework, rocky planets are local pockets of free energy that have the potential to drive the emergence of dynamically persistent systems that coevolve with one another. Examples of dynamically persistent planetary phenomena include magnetic dynamos, mantle convection, tectonic regimes, deep volatile cycles, global climate feedbacks, biogeochemical cycles, and the biosphere. When two or more processes couple to one another such that they gain causal efficacy over one another's persistence, some degree of planetary-scale homeostasis may emerge. In astrobiology, Earthlike exoplanets are often considered to be priority targets for the search for life elsewhere. We suggest that a process-based framework for Earthlikeness has the potential to widen our search space and inspire novel planetary-scale biosignatures, or “Gaiasignatures,” that may be essential for detecting exoplanetary biospheres. Additionally, a process-based view of life can influence the development of agnostic biosignatures at all scales. In contrast to the dominant scientific perspective, which has tended to engender a materialistic worldview, relational ontologies may contribute to our scientific understanding of Earth as a network of dynamically persistent systems, humanity as an integral part of nature, and the search for life in the universe. A process-based framework may offer a better gauge of a planetary body's degree of “Earthlikeness” than physical or material considerations The search for life on exoplanets may require looking for “Gaiasignatures”—signs of a biosphere coupling with its geosphere in a dynamically persistent fashion By virtue of contrasting with dominant scientific worldviews, the ontology of relationality intrinsic to a process-bas

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Effects of galaxy environment on merger fraction?

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Astronomy and Astrophysics 2024年 686卷

作者： Pearson, W.J. Santos, D.J.D. Goto, T. Huang, T.-C. Kim, S.J. Matsuhara, H. Pollo, A. Ho, S.C.-C. Hwang, H.S. Malek, K. Nakagawa, T. Romano, M. Serjeant, S. Suelves, L.E. Shim, H. White, G.J. National Centre for Nuclear Research Pasteura 7 Warszawa02-093 Poland Max Planck Institute for Extraterrestrial Physics Gießenbachstraße 1 Garching85748 Germany Institute of Astronomy National Tsing Hua University 101 Section 2. Kuang-Fu Road Hsinchu30013 Taiwan Department of Space and Astronautical Science Graduate University for Advanced Studies SOKENDAI Shonankokusaimura Hayama Miura District Kanagawa240-0193 Japan Institute of Space and Astronautical Science Japan Aerospace Exploration Agency 3-1-1 Yoshinodai Chuo-ku Kanagawa Sagamihara252-5210 Japan Research School of Astronomy and Astrophysics The Australian National University CanberraACT2611 Australia Centre for Astrophysics and Supercomputing Swinburne University of Technology PO Box 218 HawthornVIC3122 Australia OzGrav The Australian Research Council Centre of Excellence for Gravitational Wave Discovery HawthornVIC3122 Australia ASTRO3D The Australian Research Council Centre of Excellence for All-sky Astrophysics in 3D CanberraACT2611 Australia Astronomy Program Department of Physics and Astronomy Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of SNU Astronomy Research Center Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of INAF – Osservatorio Astronomico di Padova Vicolo dell’Osservatorio 5 Padova35122 Italy School of Physical Sciences The Open University Walton Hall Milton KeynesMK7 6AA United Kingdom Department of Earth Science Education Kyungpook National University 80 Daehak-ro Buk-gu Daegu41566 Korea Republic of Space Science and Technology Division RALSpace STFC Rutherford Appleton Laboratory Chilton DidcotOX11 0QX United Kingdom

Aims. In this work we examine how environment influences the merger fraction, from the low density field environment to higher density groups and clusters. We also study how the properties of a group or cluster, as well as the position of a galaxy in the group or cluster, influences the merger fraction. Methods. We identified galaxy groups and clusters in the North Ecliptic Pole using a friends-of-friends algorithm and the local density. Once identified, we determined the central galaxies, group radii, velocity dispersions, and group masses of these groups and clusters. Merging systems were identified with a neural network as well as visually. With these identifications and properties of groups and clusters and merging galaxy identifications, we examined how the merger fraction changes as the local density changes for all galaxies as well as how the merger fraction changes as the properties of the groups or clusters change. Results. We find that the merger fraction increases as local density increases and decreases as the velocity dispersion increases, as is often found in the literature. A decrease in merger fraction as the group mass increases is also found. We also find that groups with larger radii have higher merger fractions. The number of galaxies in a group does not influence the merger fraction. Conclusions. The decrease in merger fraction as group mass increases is a result of the link between group mass and velocity dispersion. Hence, this decrease in merger fraction with increasing mass is a result of the decrease of merger fraction with velocity dispersion. The increasing relation between group radii and merger fraction may be a result of larger groups having smaller velocity dispersion at a larger distance from the centre or larger groups hosting smaller, infalling groups with more mergers. However, we do not find evidence of smaller groups having higher merger fractions. c The Authors 2024.

关键词： Galaxies

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