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
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.
{"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":"32 1","pages":""},"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}
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$+$1718 could be an extragalactic object with a redshifted Fe line.
{"title":"Plasma diagnostics of supernova remnant 3C 400.2 by Suzaku observations","authors":"Masataka Onuma, Kumiko K Nobukawa, Masayoshi Nobukawa, Shigeo Yamauchi, Hideki Uchiyama","doi":"10.1093/pasj/psae081","DOIUrl":"https://doi.org/10.1093/pasj/psae081","url":null,"abstract":"We report on the results of plasma diagnostics of the supernova remnant (SNR) 3C 400.2, which has been reported to have a recombining plasma by previous studies. For careful background estimation, we simultaneously fitted spectra extracted from the SNR and background regions and evaluated the SNR emission contaminating the background-region spectrum as well as the background emission in the source-region spectrum. The SNR emission is explained by the collisional ionization equilibrium plasma originating from the interstellar medium and the ionizing plasma originating from the ejecta, in contrast to previous studies. In addition, we found an unidentified X-ray source near the SNR, Suzaku J1937.4$+$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$+$1718 could be an extragalactic object with a redshifted Fe line.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"40 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fumika Demachi, Yasuo Fukui, Rin I Yamada, Kengo Tachihara, Takahiro Hayakawa, Kazuki Tokuda, Shinji Fujita, Masato I N Kobayashi, Kazuyuki Muraoka, Ayu Konishi, Kisetsu Tsuge, Toshikazu Onishi, Akiko Kawamura
We investigated the giant molecular clouds (GMCs) in M 74 (NGC 628), using data obtained from the PHANGS (Physics at High Angular resolution in Nearby GalaxieS) project. We applied GMC types according to the activity of star formation: Type I without star formation, Type II with H$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.
我们利用 PHANGS（Physics at High Angular Resolution in Nearby GalaxieS）项目获得的数据研究了 M 74（NGC 628）中的巨分子云（GMC）。我们根据恒星形成的活跃程度划分了 GMC 类型：I型没有恒星形成，II型的H$alpha$光度（$L_{mathrm{Halpha }}$）小于$10^{37.5}rm{ergs ^{-1}}$，III型的$L_{mathrm{Halpha }}$大于$10^{37.5}rm{ergs ^{-1}}$。总共发现了 432 个 GMC，其中 I 型、II 型和 III 型分别有 59 个、201 个和 172 个 GMC。GMC的大小和质量范围分别为23到238 pc和10^{4.9}$到10^{7.1}/, M_{odot }$，表明从I型到III型，质量和半径都在增加。小于 4 Myr 的星团和 H ii 区域都集中在一个 GMC 的 150 pc 范围内，这表明这些年轻天体和 GMC 之间有着紧密的联系。从Ⅰ型到Ⅲ型，virial 比率都在下降，表明Ⅲ型 GMC 是三种类型中引力最松弛的。我们解释说，GMCs 从 I 型演化到 III 型，就像以前在大麦哲伦云中观测到的那样。根据稳态假设，I、II 和 III 型的演化时间尺度分别为 1、5 和 4 Myr。我们假设 III 型的时间尺度等于相关星团的年龄，这表明大麦哲伦云的寿命为 10 Myr 或更长。尽管 Chevance 等人（2020，MNRAS，493，2872）使用相同的 M 74 PHANGS 数据集研究了 GMC，但他们并没有定义 GMC，而是得出了非恒星形成阶段持续时间为 20 Myr 的演化图景，这比 4 Myr 长了五倍。我们将目前的结果与 Chevance 等人（2020，MNRAS，493，2872）的结果进行了比较，认为定义单个 GMC 对于理解 GMC 演化是至关重要的。
{"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":"60 1","pages":""},"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}
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
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.
巨分子云（GMCs）是高质恒星形成的主要场所，其演化是揭示星系演化的一个重要过程。利用ALMA-ACA（阿塔卡马大型毫米波/亚毫米波阵列-阿塔卡马紧凑阵列）巡天得到的M 33的巨分子云目录，我们根据848个巨分子云与H ii区的关联以及它们的H$alpha$光度$L, (rm{H}alpha)$把它们分成了三种类型：I 型不与任何 H ii 区域相关；II 型与 H ii 区域的亮度为 $L, (rm{H}alpha )$$lt 10^{37.5}$ erg s$^{-1}$；III 型与 H ii 区域的亮度为 $L, (rm{H}alpha )$$geqq$ $10^{37.5}$ erg s$^{-1}$。根据这些标准，得出了 224 个 I 型 GMCs、473 个 II 型 GMCs 和 151 个 III 型 GMCs。不同类型的 GMC 在物理性质上有不同的变化；从 I 型到 III 型，GMC 的质量、半径、速度弥散和 $^{13}$CO 检测率都在系统地增加，此外，III 型 GMC 最接近病毒平衡。III型GMC与小于$10:$Myr的星团的空间相关性最高，II型GMC的相关性适中，而I型GMC几乎没有相关性。我们认为这些类型表明了一个从Ⅰ型到Ⅱ型，再到Ⅲ型的演化序列，其时间尺度分别为4 Myr、13 Myr和5 Myr，假设Ⅱ型GMC的时间尺度与大麦哲伦云相同，则表明GMC的寿命为22 Myr。演化后的 GMC 都集中在旋臂上，而年轻的 GMC 则远离旋臂，无论是在旋臂的前侧还是后侧。这表明GMC通过螺旋势能相互碰撞，导致GMC压缩，并引发高质恒星形成，这可能支持动态螺旋模型。总之，我们认为GMC演化概念有助于阐明星系的演化，包括旋臂的形成。
{"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":"45 1","pages":""},"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}
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.
{"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":"60 1","pages":""},"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}
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.
碳氢化合物尘埃是星际尘埃的主要成分之一，主要由多环芳香烃和脂肪烃组成。虽然碳氢化合物尘埃被认为是在星际辐射场或冲击中被处理的，但详细的处理机制还不完全清楚。我们通过分析138个红移为$z lt 0.3$的恒星形成星系中碳氢化合物尘埃发出的光度与总红外光度$(L_{mathrm{IR}})$之间的关系来研究碳氢化合物尘埃的处理过程。利用AKARI获得的2.5-5, mu {rm m}$近红外光谱，我们得出了3.3, mu {rm m}$处的芳香烃特征（$L_mathrm{aromatic}$）和3.4-3.6, mu {rm m}$处的脂肪烃特征（$L_mathrm{aliphatic}$）的光度。我们还利用AKARI、WISE和IRAS的测光数据，对138个星系的光谱能量分布进行建模，得出了$L_mathrm{IR}$和辐射场强。我们发现$L_mathrm{IR}$较高的星系往往表现出较低的$L_mathrm{脂肪族}/L_mathrm{芳香族}$比率。此外，我们还发现$L_mathrm{aliphatic}/L_mathrm{aromatic}$比值与辐射场强之间存在反相关关系，而且低$L_mathrm{aliphatic}/L_mathrm{aromatic}$比值的星系主要是合并星系。这些结果支持这样一种观点，即碳氢化合物尘埃是在星系合并过程中，在强辐射场和/或冲击下通过光解离处理的；在这种恶劣的星际条件下，$L_mathrm{脂肪族}/L__mathrm{芳香族}$比值很可能会降低，因为众所周知脂肪族键的化学性质比芳香族键弱。
{"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":"65 1","pages":""},"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}
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.
{"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":"60 1","pages":""},"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}
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.
M 31圆盘的西北侧被称为近侧，因为从其摄影测光中发现了球状星团的不同变红现象。本文报告了一个简单的几何模型，用于评估该效应的可见度，并将其应用于已发表的关于三个螺旋星系（M 31、M 33 和 NGC 253）球状星团系统的 CCD 摄影测量。在 M 31 和 NGC 253 中，球状星团系统的色差是由不同的变红引起的，这一点得到了证实；但是 M 33 的数据不够充分。分析结果再次证实了目前所采用的解释，即星系盘小轴线上的一侧是离我们较近的一侧，在这一侧可以看到更明显的尘埃特征和星际变红现象，并为利用具有已识别螺旋缠绕（S 向或 Z 向）的螺旋星系来研究宇宙中星系的大尺度自旋分布提供了新的依据。
{"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":"111 1","pages":""},"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}
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.
{"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":"47 1","pages":""},"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}
Yao Li, Duo Cao, Yi Zhang, Xiaoyong He, Feng Liu, Wangzhou Shi, Chenggang Shu
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.
{"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":"22 1","pages":""},"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}
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