Publications of the Astronomical Society of Japan最新文献

{"title":"Low abundances of TiO and VO on the dayside of KELT-9 b: Insights from ground-based photometric observations","authors":"Yuya Hayashi, Norio Narita, Akihiko Fukui, Quentin Changeat, Kiyoe Kawauchi, Kai Ikuta, Enric Palle, Felipe Murgas, Hannu Parviainen, Emma Esparza-Borges, Alberto Peláez-Torres, Pedro Pablo Meni Gallardo, Giuseppe Morello, Gareb Fernández-Rodríguez, Néstor Abreu García, Sara Muñoz Torres, Yéssica Calatayud Borrás, Pilar Montañés Rodríguez, John H Livingston, Noriharu Watanabe, Jerome P de Leon, Yugo Kawai, Keisuke Isogai, Mayuko Mori","doi":"10.1093/pasj/psae075","DOIUrl":"https://doi.org/10.1093/pasj/psae075","url":null,"abstract":"We present ground-based photometric observations of secondary eclipses of the hottest known planet KELT-9 b using MuSCAT2 and Sinistro. We detect secondary eclipse signals in i and $z_{rm s}$ with eclipse depths of $373^{+74}_{-75}$ and $638^{+199}_{-178}$ parts per million, respectively. We perform an atmospheric retrieval on the emission spectrum combined with the data from HST/WFC3, Spitzer, TESS, and CHEOPS to obtain the temperature profile and chemical abundances, including TiO and VO, which have been thought to produce temperature inversion structures in the dayside of ultra-hot Jupiters. While we confirm a strong temperature inversion structure, we find low abundances of TiO and VO with mixing ratios of $rm {log(TiO)}=-7.80^{+0.15}_{-0.30}$ and $rm {log(VO)}=-9.60^{+0.64}_{-0.57}$, respectively. The low abundances of TiO and VO are consistent with theoretical predictions for such an ultra-hot atmosphere. In such low abundances, TiO and VO have little effect on the temperature structure of the atmosphere. The abundance of ${rm e}^{-}$, which serves as a proxy for ${rm H}^{-}$ ions in this study, is found to be high, with $rm {log(e^-)}=-4.89pm {0.06}$. These results indicate that the temperature inversion in KELT-9 b’s dayside atmosphere is likely not caused by ${rm TiO/VO}$, but rather by the significant abundance of ${rm H}^{-}$ ions. The best-fitting model cannot fully explain the observed spectrum, and chemical species not included in the retrieval may introduce modeling biases. Future observations with broader wavelength coverage and higher spectral resolution are expected to provide more accurate diagnostics on the presence and abundances of ${rm TiO/VO}$. These advanced observations will overcome the limitations of current data from HST and photometric facilities, which are constrained by narrow wavelength coverage and instrumental systematics.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plasma diagnostics of supernova remnant 3C 400.2 by Suzaku observations","authors":"Masataka Onuma, Kumiko K Nobukawa, Masayoshi Nobukawa, Shigeo Yamauchi, Hideki Uchiyama","doi":"10.1093/pasj/psae081","DOIUrl":"https://doi.org/10.1093/pasj/psae081","url":null,"abstract":"We report on the results of plasma diagnostics of the supernova remnant (SNR) 3C 400.2, which has been reported to have a recombining plasma by previous studies. For careful background estimation, we simultaneously fitted spectra extracted from the SNR and background regions and evaluated the SNR emission contaminating the background-region spectrum as well as the background emission in the source-region spectrum. The SNR emission is explained by the collisional ionization equilibrium plasma originating from the interstellar medium and the ionizing plasma originating from the ejecta, in contrast to previous studies. In addition, we found an unidentified X-ray source near the SNR, Suzaku J1937.4$+$1718, which is accompanied by an emission line at $sim$4.4 keV with a $2.8sigma$ confidence level. Because there is no striking atomic line at the energy in the rest frame, Suzaku J1937.4$+$1718 could be an extragalactic object with a redshifted Fe line.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Giant molecular clouds and their type classification in M 74: Toward understanding star formation and cloud evolution","authors":"Fumika Demachi, Yasuo Fukui, Rin I Yamada, Kengo Tachihara, Takahiro Hayakawa, Kazuki Tokuda, Shinji Fujita, Masato I N Kobayashi, Kazuyuki Muraoka, Ayu Konishi, Kisetsu Tsuge, Toshikazu Onishi, Akiko Kawamura","doi":"10.1093/pasj/psae071","DOIUrl":"https://doi.org/10.1093/pasj/psae071","url":null,"abstract":"We investigated the giant molecular clouds (GMCs) in M 74 (NGC 628), using data obtained from the PHANGS (Physics at High Angular resolution in Nearby GalaxieS) project. We applied GMC types according to the activity of star formation: Type I without star formation, Type II with H$alpha$ luminosity ($L_{mathrm{Halpha }}$) less than $10^{37.5} rm{erg s ^{-1}}$, and Type III with $L_{mathrm{Halpha }}$ greater than $10^{37.5} rm{erg s^{-1}}$. A total of 432 GMCs were identified, with 59, 201, and 172 GMCs, for Types I, II, and III, respectively. The size and mass of the GMCs range from 23 to 238 pc and $10^{4.9}$ to $10^{7.1}, M_{odot }$, indicating that the mass and radius increase from Types I to III. Clusters younger than 4 Myr and H ii regions are concentrated within 150 pc of a GMC, indicating a tight association between these young objects and GMCs. The virial ratio decreases from Type I to Type III, indicating that Type III GMCs are the most gravitationally relaxed among the three. We interpret that the GMCs evolve from Type I to Type III, as previously observed in the Large Magellanic Cloud. Based on a steady-state assumption, the estimated evolutionary timescales of Types I, II, and III are 1, 5, and 4 Myr, respectively. We assume that the timescale of Type III is equal to the age of the associated clusters, indicating a GMC lifetime of 10 Myr or longer. Although Chevance et al. (2020, MNRAS, 493, 2872) investigated GMCs using the same PHANGS dataset of M 74, they did not define a GMC, reaching an evolutionary picture with a 20 Myr duration of the non-star-forming phase, which is five times longer than 4 Myr. We compare the present results with those of Chevance et al. (2020, MNRAS, 493, 2872) and argue that defining individual GMCs is essential for understanding GMC evolution.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ACA CO(J = 2–1) mapping of the nearest spiral galaxy M 33. II. Exploring the evolution of giant molecular clouds","authors":"Ayu Konishi, Kazuyuki Muraoka, Kazuki Tokuda, Shinji Fujita, Yasuo Fukui, Rin I Yamada, Fumika Demachi, Kengo Tachihara, Masato I N Kobayashi, Nario Kuno, Kisetsu Tsuge, Hidetoshi Sano, Rie E Miura, Akiko Kawamura, Toshikazu Onishi","doi":"10.1093/pasj/psae073","DOIUrl":"https://doi.org/10.1093/pasj/psae073","url":null,"abstract":"The evolution of giant molecular clouds (GMCs), the main sites of high-mass star formation, is an essential process to unravel the galaxy evolution. Using a GMC catalogue of M 33 from the ALMA-ACA (Atacama Large Millimeter/submillimeter Array–Atacama Compact Array) survey, we classified 848 GMCs into three types based on the association with H ii regions and their H$alpha$ luminosities $L, (rm{H}alpha )$: Type I is associated with no H ii regions; Type II with H ii regions of $L, (rm{H}alpha )$ $lt 10^{37.5}$ erg s$^{-1}$; and Type III with H ii regions of $L, (rm{H}alpha )$ $geqq$ $10^{37.5}$ erg s$^{-1}$. These criteria yield 224 Type I GMCs, 473 Type II GMCs, and 151 Type III GMCs. GMCs show changes in their physical properties according to the types; mass, radius, velocity dispersion, and $^{13}$CO detection rate of GMCs systematically increase from Type I to Type III, and additionally, Type III GMCs are closest to virial equilibrium. Type III GMCs show the highest spatial correlation with clusters younger than $10:$Myr, Type II GMCs moderate correlation, and Type I GMCs are almost uncorrelated. We interpret that these types indicate an evolutionary sequence from Type I to Type II, and then to Type III with timescales of 4 Myr, 13 Myr, and 5 Myr, respectively, indicating a GMC lifetime of 22 Myr by assuming that a Type II GMC has the same timescale as the Large Magellanic Cloud. The evolved GMCs are concentrated on the spiral arms, while the younger GMCs are apart from the arm, both to the leading and trailing sides. This indicates that GMCs collide with each other via the spiral potential, leading to the compression of GMCs and the triggering of high-mass star formation, which may support the dynamic spiral model. Overall, we suggest that the GMC evolution concept helps illuminate the galaxy evolution, including the spiral arm formation.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MK-like spectral classification for hot subdwarf stars with LAMOST spectra","authors":"Xuan Zou, Zhenxin Lei","doi":"10.1093/pasj/psae072","DOIUrl":"https://doi.org/10.1093/pasj/psae072","url":null,"abstract":"An MK-like spectral classification has been conducted for 1224 hot subdwarf stars with LAMOST DR9 low-resolution spectra. The whole sample was divided into four categories according to the spectral line characteristics: He-normal, He-weak, He-strong C, and He-strong. Each selected spectrum was assigned a spectral class, a luminosity class, and a helium class by comparing the line depth and width with standard spectra selected in LAMOST. Relationships between atmospheric parameters and spectral classification are also presented.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Processing of hydrocarbon dust in star-forming galaxies revealed with AKARI","authors":"Tsubasa Kondo, Akino Kondo, Katsuhiro L Murata, Takuma Kokusho, Shinki Oyabu, Toyoaki Suzuki, Risako Katayama, Hidehiro Kaneda","doi":"10.1093/pasj/psae069","DOIUrl":"https://doi.org/10.1093/pasj/psae069","url":null,"abstract":"Hydrocarbon dust is one of the dominant components of interstellar dust, which mainly consists of polycyclic aromatic hydrocarbons and aliphatic hydrocarbons. While hydrocarbon dust is thought to be processed in interstellar radiation fields or shocks, detailed processing mechanisms are not completely understood yet. We investigate the processing of hydrocarbon dust by analyzing the relation between the luminosities emitted by hydrocarbon dust and the total infrared luminosities $(L_{mathrm{IR}})$ for 138 star-forming galaxies at redshift $z lt 0.3$. Using near-infrared 2.5–5$, mu {rm m}$ spectra obtained with AKARI, we derived the luminosities of the aromatic hydrocarbon feature at 3.3$, mu {rm m}$ ($L_mathrm{aromatic}$) and the aliphatic hydrocarbon feature at 3.4–3.6$, mu {rm m}$ ($L_mathrm{aliphatic}$). We also derived $L_mathrm{IR}$ and the radiation field strength by modeling the spectral energy distributions of the 138 galaxies with AKARI, WISE, and IRAS photometry data. We find that galaxies with higher $L_mathrm{IR}$ tend to exhibit lower $L_mathrm{aliphatic}/L_mathrm{aromatic}$ ratios. Furthermore, we find that there is an anti-correlation between $L_mathrm{aliphatic}/L_mathrm{aromatic}$ ratios and the radiation field strength, and also that the galaxies with low $L_mathrm{aliphatic}/L_mathrm{aromatic}$ ratios are dominated by merger galaxies. These results support the suggestion that hydrocarbon dust is processed through photodissociation in strong radiation fields and/or shocks during merging processes of galaxies; the $L_mathrm{aliphatic}/L_mathrm{aromatic}$ ratio is likely to decrease in such harsh interstellar conditions since the aliphatic bonds are known to be chemically weaker than the aromatic bonds.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141948816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Upper limit on the coronal cosmic ray energy budget in Seyfert galaxies","authors":"Yoshiyuki Inoue, Shinsuke Takasao, Dmitry Khangulyan","doi":"10.1093/pasj/psae065","DOIUrl":"https://doi.org/10.1093/pasj/psae065","url":null,"abstract":"The IceCube Collaboration has reported possible detections of high-energy neutrinos from nearby Seyfert galaxies. While central hot coronae are proposed as the primary neutrino production site, the exact coronal cosmic ray energy budget has been loosely constrained. In this study, we propose a new stringent upper bound on the coronal cosmic ray energy budget of Seyfert galaxies, considering both accretion dynamics and observed properties of radio-quiet Seyfert galaxies. Notably, even under the calorimetric condition where cosmic rays lose all their energy, our limit indicates that the coronal neutrino flux of NGC 1068 is about an order of magnitude fainter than the observed levels. This discrepancy suggests the need for further theoretical and observational investigations on the IceCube signals from Seyfert galaxies.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diffraction modelling of a 2023 March 5 stellar occultation by subkilometer-sized asteroid (98943) 2001 CC21","authors":"Ko Arimatsu, Fumi Yoshida, Tsutomu Hayamizu, Miyoshi Ida, George L Hashimoto, Takashi Abe, Hiroshi Akitaya, Akari Aratani, Hidekazu Fukuda, Yasuhide Fujita, Takao Fujiwara, Toshihiro Horikawa, Tamio Iihoshi, Kazuyoshi Imamura, Ryo Imazawa, Hisashi Kasebe, Ryosuke Kawasaki, Hiroshi Kishimoto, Kazuhisa Mishima, Machiko Miyachi, Masanori Mizutani, Maya Nakajima, Hiroyoshi Nakatani, Kazuhiko Okamura, Misaki Okanobu, Masataka Okuda, Yuji Suzuki, Naoto Tatsumi, Masafumi Uno, Hidehito Yamamura, Mikoto Yasue, Hideki Yoshihara, Masatoshi Hirabayashi, Makoto Yoshikawa","doi":"10.1093/pasj/psae060","DOIUrl":"https://doi.org/10.1093/pasj/psae060","url":null,"abstract":"We present an analysis of a stellar occultation event caused by a near-Earth asteroid (98943) 2001 CC21, an upcoming flyby target in the Hayabusa2 extended mission, on 2023 March 5. To determine the asteroid’s shape from diffraction-affected light curves accurately, we developed a novel data-reduction technique named the Diffracted Occultation’s United Simulator for Highly Informative Transient Explorations (DOUSHITE). Using DOUSHITE-generated synthetic models, we derived constraints on (98943) 2001 CC21’s shadow shape from the single-chord occultation data. Our results suggest a significant elongation of the shadow with an axis ratio of $b/a = 0.37pm 0.09$. This shape could be crucial for planning Hayabusa2’s high-speed flyby to optimise the limited imaging opportunities.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spin parity of spiral galaxies. IV. Differential reddening of globular cluster systems of nearby spiral galaxies","authors":"Masanori Iye, Masafumi Yagi","doi":"10.1093/pasj/psae064","DOIUrl":"https://doi.org/10.1093/pasj/psae064","url":null,"abstract":"The north-west side of the disk of M 31 is known as the near side because of the differential reddening of globular clusters found from their photographic photometry. This paper reports a simple geometric model to evaluate the visibility of the effect and its application to published CCD photometry on globular cluster systems of three spiral galaxies, M 31, M 33, and NGC 253. The color difference of globular cluster systems due to differential reddening was confirmed for M 31 and NGC 253; however, the data for M 33 were insufficient. The analysis reaffirms the currently adopted interpretation that the side on the minor axis of the galactic disk, where more conspicuous dust features and interstellar reddening are visible, is the nearer side to us and provides an additional basis for using spiral galaxies with identified spiral windings, S-wise or Z-wise, to study the large-scale spin distribution of galaxies in the universe.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new LHe-free cryostat for the heterodyne SIS receiver for the Leighton Chajnantor Telescope","authors":"Yao Li, Duo Cao, Yi Zhang, Xiaoyong He, Feng Liu, Wangzhou Shi, Chenggang Shu","doi":"10.1093/pasj/psae063","DOIUrl":"https://doi.org/10.1093/pasj/psae063","url":null,"abstract":"The Leighton Chajnantor Telescope (LCT) is an international collaborative program among Caltech, Shanghai Normal University (ShNU), and Universidad de Concepción (UdeC), aiming at the refurbishment and relocation of the Caltech Submillimeter Observatory (CSO) telescope from Mauna Kea, Hawaii, to the Chajnantor Plateau, northern Chile. A suite of excellent-sensitivity heterodyne superconductor–insulator–superconductor (SIS) receivers will be deployed to the telescope as the first set of instrumentations for high-resolution spectral observation. However, the current refrigeration technology for this receiver utilizes liquid helium (LHe), which greatly increases the cost of cooling and labor. To address this problem, a new LHe-free cryostat for the LCT heterodyne SIS receiver has been designed, fabricated, and tested. Mechanical and thermal analyses were performed to ensure that the cryostat meets the requirements of the telescope pointing accuracy and the SIS junction working environment, respectively. The experiment testing results are in good agreement with the calculation and analysis, indicating that the proposed LHe-free cryostat meets the operational requirements of the telescope at the new site.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141739638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}