Abstract We developed a multiregion radiation model for the evolution of flux and spectral index with time. In this model, each perturbation component in the jet produces an independent flare. The model can be used to study the decomposition of microvariability, the structural scale of the perturbed components, and the physical parameters of the acceleration processes. Based on the shock acceleration model for a relativistic jet, the influence of the acceleration parameters on multiband flare parameters is calculated. We present the results of multiband optical microvariability of the blazar BL Lacertae observed during 89 nights in the period from 2009 to 2021, and use them as a sample for model fitting. The results show that both the amplitude and duration of flares decomposed from the microvariability light curves conform to a log-normal distribution. The time delays between the optical bands follow a normal distribution and amount to several minutes, which corroborate with both predictions from the theoretical model and the calculation of the discrete correlation function. Using the spectral index evolution and the simultaneous fitting of the multiband variability curves, we obtain the acceleration and radiation parameters to constrain and distinguish the origins of different flares. Based on the flare decomposition, we can effectively reproduce the time-domain evolution trends of the optical variations and energy spectrum, and explain the various redder-when-brighter and bluer-when-brighter behaviors.
{"title":"A Small-scale Structure Model of a Jet Based on Observations of Microvariability","authors":"Jingran Xu, Shaoming Hu, Xu Chen, Yunguo Jiang, Sofya Alexeeva","doi":"10.3847/1538-4365/aceda8","DOIUrl":"https://doi.org/10.3847/1538-4365/aceda8","url":null,"abstract":"Abstract We developed a multiregion radiation model for the evolution of flux and spectral index with time. In this model, each perturbation component in the jet produces an independent flare. The model can be used to study the decomposition of microvariability, the structural scale of the perturbed components, and the physical parameters of the acceleration processes. Based on the shock acceleration model for a relativistic jet, the influence of the acceleration parameters on multiband flare parameters is calculated. We present the results of multiband optical microvariability of the blazar BL Lacertae observed during 89 nights in the period from 2009 to 2021, and use them as a sample for model fitting. The results show that both the amplitude and duration of flares decomposed from the microvariability light curves conform to a log-normal distribution. The time delays between the optical bands follow a normal distribution and amount to several minutes, which corroborate with both predictions from the theoretical model and the calculation of the discrete correlation function. Using the spectral index evolution and the simultaneous fitting of the multiband variability curves, we obtain the acceleration and radiation parameters to constrain and distinguish the origins of different flares. Based on the flare decomposition, we can effectively reproduce the time-domain evolution trends of the optical variations and energy spectrum, and explain the various redder-when-brighter and bluer-when-brighter behaviors.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135199608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-28DOI: 10.3847/1538-4365/acec79
Kenneth P. Dere, G. Del Zanna, P. R. Young, E. Landi
Abstract The CHIANTI atomic database provides sets of assessed data that are used for simulating spectral observations of astrophysical plasmas. This article describes updates that will be released as version 10.1 of the database. A key component of CHIANTI is the provision of ionization and recombination rates that are used to compute the ionization balance of a plasma over a range of temperatures. Parameters for calculating the ionization rates of all stages of ions from H through Zn were compiled and inserted into the CHIANTI database in 2009. These were based on all measurements that were available at the time and supplemented with distorted wave calculations. Since then, there have been a number of new laboratory measurements for ions that produce spectral lines that are commonly observed. Parameters have been fit to these new measurements to provide improved ability to reproduce the ionization cross sections and rate coefficients, and these are added to the database. CHIANTI 10.1 also includes new recombination rates for the phosphorus isoelectronic sequence, and the updated ionization and recombination rates have been used to calculate a new ionization equilibrium file. In addition, CHIANTI 10.1 has new electron collision and radiative data sets for eight ions in the nitrogen and oxygen isoelectronic sequences and updated energy level and wavelength data for six other ions.
{"title":"CHIANTI—An Atomic Database for Emission Lines. XVII. Version 10.1: Revised Ionization and Recombination Rates and Other Updates*","authors":"Kenneth P. Dere, G. Del Zanna, P. R. Young, E. Landi","doi":"10.3847/1538-4365/acec79","DOIUrl":"https://doi.org/10.3847/1538-4365/acec79","url":null,"abstract":"Abstract The CHIANTI atomic database provides sets of assessed data that are used for simulating spectral observations of astrophysical plasmas. This article describes updates that will be released as version 10.1 of the database. A key component of CHIANTI is the provision of ionization and recombination rates that are used to compute the ionization balance of a plasma over a range of temperatures. Parameters for calculating the ionization rates of all stages of ions from H through Zn were compiled and inserted into the CHIANTI database in 2009. These were based on all measurements that were available at the time and supplemented with distorted wave calculations. Since then, there have been a number of new laboratory measurements for ions that produce spectral lines that are commonly observed. Parameters have been fit to these new measurements to provide improved ability to reproduce the ionization cross sections and rate coefficients, and these are added to the database. CHIANTI 10.1 also includes new recombination rates for the phosphorus isoelectronic sequence, and the updated ionization and recombination rates have been used to calculate a new ionization equilibrium file. In addition, CHIANTI 10.1 has new electron collision and radiative data sets for eight ions in the nitrogen and oxygen isoelectronic sequences and updated energy level and wavelength data for six other ions.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135343809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-28DOI: 10.3847/1538-4365/acee73
Kai Xiao, Haibo Yuan, Bowen Huang, Ruoyi Zhang, Lin Yang, Shuai Xu
Abstract In this work, we perform the recalibration of Pan-STARRS1 (PS1) photometry by correcting for position-dependent systematic errors using the spectroscopy-based stellar color regression (SCR) method, the photometry-based SCR method, and the Gaia BP/RP synthetic photometry method. We confirm the significant large-scale and small-scale spatial variation of the magnitude offsets for all the grizy filters. We show that the PS1 photometric calibration precisions in the grizy filters are around 5–7 mmag when averaged over 14′ regions. We note a much larger calibration error up to 0.04 mag in the Galactic plane, which is probably caused by the systematic errors of the PS1 magnitudes in crowded fields. The results of the three methods are consistent with each other within 1–2 mmag or better for all the filters. We provide 2D maps and a Python package to correct for position-dependent magnitude offsets of PS1, which can be used for high-precision investigations and as a reference to calibrate other surveys.
{"title":"Improvement of Pan-STARRS Photometric Calibration with LAMOST and Gaia","authors":"Kai Xiao, Haibo Yuan, Bowen Huang, Ruoyi Zhang, Lin Yang, Shuai Xu","doi":"10.3847/1538-4365/acee73","DOIUrl":"https://doi.org/10.3847/1538-4365/acee73","url":null,"abstract":"Abstract In this work, we perform the recalibration of Pan-STARRS1 (PS1) photometry by correcting for position-dependent systematic errors using the spectroscopy-based stellar color regression (SCR) method, the photometry-based SCR method, and the Gaia BP/RP synthetic photometry method. We confirm the significant large-scale and small-scale spatial variation of the magnitude offsets for all the grizy filters. We show that the PS1 photometric calibration precisions in the grizy filters are around 5–7 mmag when averaged over 14′ regions. We note a much larger calibration error up to 0.04 mag in the Galactic plane, which is probably caused by the systematic errors of the PS1 magnitudes in crowded fields. The results of the three methods are consistent with each other within 1–2 mmag or better for all the filters. We provide 2D maps and a Python package to correct for position-dependent magnitude offsets of PS1, which can be used for high-precision investigations and as a reference to calibrate other surveys.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135344773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-27DOI: 10.3847/1538-4365/aced88
Zhi 志 Li 李, Yan 焱 Li 李
Abstract To explore overshoot mixing and rotational mixing beyond the convective core during the core He-burning phase in massive stars, we computed a grid of stellar models, both rotating and nonrotating, with the k − ω model at Z = 0.02, covering a mass range of 25–120 M ⊙ . The rotating models start with a rotation rate of v ini / v crit = 0.4 at the zero-age main sequence, and the evolution is computed until the end of the central carbon-burning phase. Models with the k − ω model provide larger convective cores and a broadening of the main-sequence width. The diffusive-overshoot models with f ov = 0.027 are, on average, closer to the k − ω models for massive stars at Z = 0.02, particularly for the stars with masses greater than 40 M ⊙ . The final masses of the Wolf–Rayet (WR) stars range from 9.5–17.5 M ⊙ and 10–23 M ⊙ for the rotating and nonrotating models, respectively. In the rotating models, the C/N ratio decreases slowly below 0.1 outside the convective core, resulting in a flatter element transition region. In addition, the lifetimes of the WNC phase are 1–4 × 10 4 yr, which is about 1 order of magnitude longer than that in the nonrotating models. The masses of the WNC stars are dominated by internal mixing processes and the maximum masses of the He-burning convective cores during the core He-burning phase are in the range of 15–35 M ⊙ . The expected WNC/WR ratios are 0.059 and 0.004 for the rotating and nonrotating models, respectively.
{"title":"Grids of Wolf–Rayet Stars Using MESA with the k − ω Model: From 25 to 120 M <sub>⊙</sub> at Z = 0.02","authors":"Zhi 志 Li 李, Yan 焱 Li 李","doi":"10.3847/1538-4365/aced88","DOIUrl":"https://doi.org/10.3847/1538-4365/aced88","url":null,"abstract":"Abstract To explore overshoot mixing and rotational mixing beyond the convective core during the core He-burning phase in massive stars, we computed a grid of stellar models, both rotating and nonrotating, with the k − ω model at Z = 0.02, covering a mass range of 25–120 M ⊙ . The rotating models start with a rotation rate of v ini / v crit = 0.4 at the zero-age main sequence, and the evolution is computed until the end of the central carbon-burning phase. Models with the k − ω model provide larger convective cores and a broadening of the main-sequence width. The diffusive-overshoot models with f ov = 0.027 are, on average, closer to the k − ω models for massive stars at Z = 0.02, particularly for the stars with masses greater than 40 M ⊙ . The final masses of the Wolf–Rayet (WR) stars range from 9.5–17.5 M ⊙ and 10–23 M ⊙ for the rotating and nonrotating models, respectively. In the rotating models, the C/N ratio decreases slowly below 0.1 outside the convective core, resulting in a flatter element transition region. In addition, the lifetimes of the WNC phase are 1–4 × 10 4 yr, which is about 1 order of magnitude longer than that in the nonrotating models. The masses of the WNC stars are dominated by internal mixing processes and the maximum masses of the He-burning convective cores during the core He-burning phase are in the range of 15–35 M ⊙ . The expected WNC/WR ratios are 0.059 and 0.004 for the rotating and nonrotating models, respectively.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135538972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-27DOI: 10.3847/1538-4365/acebe6
X. J. Yang, Aigen Li
Abstract The so-called “unidentified infrared emission” (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μ m ubiquitously seen in a wide variety of astrophysical regions are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. Astronomical PAHs often have an aliphatic component (e.g., aliphatic sidegroups like methyl –CH 3 may be attached as functional groups to PAHs) as revealed by the detection in many UIE sources of the aliphatic C–H stretching feature at 3.4 μ m. With its unprecedented sensitivity and spatial resolution, and high spectral resolution, the James Webb Space Telescope (JWST) holds great promise for revolutionizing the studies of aliphatics and aromatics in the Universe. To facilitate analyzing JWST observations, we present a theoretical framework for determining the aliphatic fractions ( η ali ) of PAHs (the fractions of C atoms in aliphatic units) from the emission intensity ratios of the 3.4 μ m aliphatic C–H feature to the 3.3 μ m aromatic C–H feature. To demonstrate the effectiveness of this framework, we compile the 3.3 and 3.4 μ m UIE data obtained in the pre-JWST era for an as-complete-as-possible sample, and then apply the framework to these pre-JWST data. We derive a median aliphatic fraction of 〈 η ali 〉 ≈ 5.4%, and find that the aliphatic fractions are the highest in protoplanetary nebulae illuminated by cool stars lacking ultraviolet radiation. Nevertheless, the “hardness” of stellar photons is not the only factor affecting the PAH aliphaticity, and other factors such as the starlight intensity may also play an important role.
在各种天体物理区域中普遍存在的3.3、6.2、7.7、8.6和11.3 μ m的所谓“不明红外发射”(UIE)特征通常归因于多环芳烃(PAH)分子。天文上的多环芳烃通常含有脂肪族成分(例如，脂肪族侧基如甲基- ch3可能作为官能团附着在多环芳烃上)，这是在许多UIE源中检测到的3.4 μ m的脂肪族C-H拉伸特征。詹姆斯韦伯太空望远镜(JWST)以其前所未有的灵敏度和空间分辨率，以及高光谱分辨率，有望革命性地研究宇宙中的脂肪族和芳烃。为了便于分析JWST观测结果，我们提出了一个从3.4 μ m脂肪族C - h特征与3.3 μ m芳香族C - h特征的发射强度比来确定多环芳烃的脂肪族分数(脂肪族单位中C原子的分数)的理论框架。为了证明该框架的有效性，我们对jwst前时代获得的3.3和3.4 μ m UIE数据进行了尽可能完整的样本编译，然后将该框架应用于jwst前时代的数据。我们得到了中间脂肪分数< η ali >≈5.4%，并发现在没有紫外线辐射的冷恒星照射的原行星状星云中脂肪分数最高。然而，恒星光子的“硬度”并不是影响多环芳烃脂肪性的唯一因素，星光强度等其他因素也可能发挥重要作用。
{"title":"Aliphatics and Aromatics in the Universe: The Pre-JWST Era","authors":"X. J. Yang, Aigen Li","doi":"10.3847/1538-4365/acebe6","DOIUrl":"https://doi.org/10.3847/1538-4365/acebe6","url":null,"abstract":"Abstract The so-called “unidentified infrared emission” (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μ m ubiquitously seen in a wide variety of astrophysical regions are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. Astronomical PAHs often have an aliphatic component (e.g., aliphatic sidegroups like methyl –CH 3 may be attached as functional groups to PAHs) as revealed by the detection in many UIE sources of the aliphatic C–H stretching feature at 3.4 μ m. With its unprecedented sensitivity and spatial resolution, and high spectral resolution, the James Webb Space Telescope (JWST) holds great promise for revolutionizing the studies of aliphatics and aromatics in the Universe. To facilitate analyzing JWST observations, we present a theoretical framework for determining the aliphatic fractions ( η ali ) of PAHs (the fractions of C atoms in aliphatic units) from the emission intensity ratios of the 3.4 μ m aliphatic C–H feature to the 3.3 μ m aromatic C–H feature. To demonstrate the effectiveness of this framework, we compile the 3.3 and 3.4 μ m UIE data obtained in the pre-JWST era for an as-complete-as-possible sample, and then apply the framework to these pre-JWST data. We derive a median aliphatic fraction of 〈 η ali 〉 ≈ 5.4%, and find that the aliphatic fractions are the highest in protoplanetary nebulae illuminated by cool stars lacking ultraviolet radiation. Nevertheless, the “hardness” of stellar photons is not the only factor affecting the PAH aliphaticity, and other factors such as the starlight intensity may also play an important role.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135536789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-22DOI: 10.3847/1538-4365/acebca
Gourab Giri, Bhargav Vaidya, Christian Fendt
Abstract X-shaped radio galaxies (XRGs) develop when certain extragalactic jets deviate from their propagation path. An asymmetric ambient medium (backflow model) or complex active galactic nucleus activity (jet-reorientation model) enforcing the jet direction to deviate may cause these structures. In this context, the present investigation focuses on the modeling of XRGs by performing 3D relativistic magnetohydrodynamic simulations. We implement different jet-propagation models applying an initially identical jet-ambient medium configuration to understand distinctive features. This study, the first of its kind, demonstrates that all adopted models produce XRGs with notable properties, thereby challenging the notion of a universal model. Jet reorientation naturally explains several contentious properties of XRGs, including wing alignment along the ambient medium’s primary axis, development of collimated lobes, and the formation of noticeably longer wings than active lobes. These XRGs disrupt the cluster medium by generating isotropic shocks and channeling more energy than in the backflow scenario. Our synthetic thermal X-ray maps of the cluster medium reveal four clear elongated cavities associated with the wing-lobe alignment, regardless of projection effects, but they affect their age estimation. We show that the depth and geometric alignment of the evolved cavities may qualify as promising characteristics of XRGs, which may be used to disentangle different formation scenarios.
{"title":"Deciphering the Morphological Origins of X-shaped Radio Galaxies: Numerical Modeling of Backflow versus Jet Reorientation","authors":"Gourab Giri, Bhargav Vaidya, Christian Fendt","doi":"10.3847/1538-4365/acebca","DOIUrl":"https://doi.org/10.3847/1538-4365/acebca","url":null,"abstract":"Abstract X-shaped radio galaxies (XRGs) develop when certain extragalactic jets deviate from their propagation path. An asymmetric ambient medium (backflow model) or complex active galactic nucleus activity (jet-reorientation model) enforcing the jet direction to deviate may cause these structures. In this context, the present investigation focuses on the modeling of XRGs by performing 3D relativistic magnetohydrodynamic simulations. We implement different jet-propagation models applying an initially identical jet-ambient medium configuration to understand distinctive features. This study, the first of its kind, demonstrates that all adopted models produce XRGs with notable properties, thereby challenging the notion of a universal model. Jet reorientation naturally explains several contentious properties of XRGs, including wing alignment along the ambient medium’s primary axis, development of collimated lobes, and the formation of noticeably longer wings than active lobes. These XRGs disrupt the cluster medium by generating isotropic shocks and channeling more energy than in the backflow scenario. Our synthetic thermal X-ray maps of the cluster medium reveal four clear elongated cavities associated with the wing-lobe alignment, regardless of projection effects, but they affect their age estimation. We show that the depth and geometric alignment of the evolved cavities may qualify as promising characteristics of XRGs, which may be used to disentangle different formation scenarios.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136060876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-22DOI: 10.3847/1538-4365/acea61
Benjamin F. Williams, Meredith Durbin, Dustin Lang, Julianne J. Dalcanton, Andrew E. Dolphin, Adam Smercina, Petia Yanchulova Merica-Jones, Daniel R. Weisz, Eric F. Bell, Karoline M. Gilbert, Léo Girardi, Karl Gordon, Puragra Guhathakurta, L. Clifton Johnson, Tod R. Lauer, Anil Seth, Evan Skillman
Abstract We present the final legacy version of stellar photometry for the Panchromatic Hubble Andromeda Treasury (PHAT) survey. We have reprocessed all of the Hubble Space Telescope Wide Field Camera 3 and Advanced Camera for Surveys near-ultraviolet (F275W, F336W), optical (F475W, F814W), and near-infrared (F110W, F160W) imaging from the PHAT survey using an improved method that optimized the survey depth and chip-gap coverage by including all overlapping exposures in all bands in the photometry. An additional improvement was gained through the use of charge transfer efficiency (CTE)–corrected input images, which provide more complete star finding as well as more reliable photometry for the NUV bands, which had no CTE correction in the previous version of the PHAT photometry. While this method requires significantly more computing resources and time than earlier versions where the photometry was performed on individual pointings, it results in smaller systematic instrumental completeness variations as demonstrated by cleaner maps in stellar density, and it results in optimal constraints on stellar fluxes in all bands from the survey data. Our resulting catalog has 138 million stars, 18% more than the previous catalog, with lower density regions gaining as much as 40% more stars. The new catalog produces nearly seamless population maps that show relatively well-mixed distributions for populations associated with ages older than 1–2 Gyr and highly structured distributions for the younger populations.
{"title":"The Panchromatic Hubble Andromeda Treasury. XXI. The Legacy Resolved Stellar Photometry Catalog","authors":"Benjamin F. Williams, Meredith Durbin, Dustin Lang, Julianne J. Dalcanton, Andrew E. Dolphin, Adam Smercina, Petia Yanchulova Merica-Jones, Daniel R. Weisz, Eric F. Bell, Karoline M. Gilbert, Léo Girardi, Karl Gordon, Puragra Guhathakurta, L. Clifton Johnson, Tod R. Lauer, Anil Seth, Evan Skillman","doi":"10.3847/1538-4365/acea61","DOIUrl":"https://doi.org/10.3847/1538-4365/acea61","url":null,"abstract":"Abstract We present the final legacy version of stellar photometry for the Panchromatic Hubble Andromeda Treasury (PHAT) survey. We have reprocessed all of the Hubble Space Telescope Wide Field Camera 3 and Advanced Camera for Surveys near-ultraviolet (F275W, F336W), optical (F475W, F814W), and near-infrared (F110W, F160W) imaging from the PHAT survey using an improved method that optimized the survey depth and chip-gap coverage by including all overlapping exposures in all bands in the photometry. An additional improvement was gained through the use of charge transfer efficiency (CTE)–corrected input images, which provide more complete star finding as well as more reliable photometry for the NUV bands, which had no CTE correction in the previous version of the PHAT photometry. While this method requires significantly more computing resources and time than earlier versions where the photometry was performed on individual pointings, it results in smaller systematic instrumental completeness variations as demonstrated by cleaner maps in stellar density, and it results in optimal constraints on stellar fluxes in all bands from the survey data. Our resulting catalog has 138 million stars, 18% more than the previous catalog, with lower density regions gaining as much as 40% more stars. The new catalog produces nearly seamless population maps that show relatively well-mixed distributions for populations associated with ages older than 1–2 Gyr and highly structured distributions for the younger populations.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136060875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-21DOI: 10.3847/1538-4365/acf0be
Julia Martikainen, Olga Muñoz, Teresa Jardiel, Juan Carlos Gómez Martín, Marco Peiteado, Yannick Willame, Antti Penttilä, Karri Muinonen, Gerhard Wurm, Tim Becker
Abstract We present an advanced light-scattering model to retrieve the optical constants of three Martian dust analogs: Johnson Space Center regolith simulant, Enhanced Mojave Mars Simulant, and Mars Global Simulant. The samples are prepared to have narrow particle-size distributions within the geometric-optics domain. We carry out laboratory measurements to obtain the particle-size distributions, shapes, and diffuse reflectance spectra of the Martian analogs deposited on a surface. Our model framework includes a ray-optics code to compute scattering properties for individual particles, and a radiative-transfer treatment to simulate the surface. The irregular shapes of the dust particles are taken into account in the model. We compare our derived imaginary parts of the refractive indices with those in the literature and find that they are much smaller than the ones that are commonly used for Martian dust. A sensitivity study shows that the retrieved optical constants are sensitive to the particle shape, which needs to be accounted for in applications that use different shapes. Finally, the derived values are validated by using them to reproduce the reflectance spectrum of the Martian surface regolith as observed by the Nadir and Occultation for Mars Discovery instrument on board the ExoMars mission.
本文提出了一种先进的光散射模型，用于获取三种火星尘埃类似物的光学常数:约翰逊航天中心风化层模拟物、增强型莫哈韦火星模拟物和火星全球模拟物。制备的样品在几何光学域内具有狭窄的粒径分布。我们进行了实验室测量，以获得沉积在火星表面的类似物的颗粒大小分布、形状和漫反射光谱。我们的模型框架包括一个射线光学代码来计算单个粒子的散射特性，以及一个辐射传输处理来模拟表面。模型中考虑了尘埃颗粒的不规则形状。我们将推导出的折射率虚部与文献中的折射率虚部进行了比较，发现它们比通常用于火星尘埃的折射率虚部小得多。灵敏度研究表明，检索到的光学常数对粒子形状很敏感，在使用不同形状的应用中需要考虑到这一点。最后，通过对ExoMars任务上的Nadir和Occultation for Mars Discovery仪器观测到的火星表面风化层的反射光谱进行再现，验证了所得值的有效性。
{"title":"Optical Constants of Martian Dust Analogs at UV–Visible–Near-infrared Wavelengths","authors":"Julia Martikainen, Olga Muñoz, Teresa Jardiel, Juan Carlos Gómez Martín, Marco Peiteado, Yannick Willame, Antti Penttilä, Karri Muinonen, Gerhard Wurm, Tim Becker","doi":"10.3847/1538-4365/acf0be","DOIUrl":"https://doi.org/10.3847/1538-4365/acf0be","url":null,"abstract":"Abstract We present an advanced light-scattering model to retrieve the optical constants of three Martian dust analogs: Johnson Space Center regolith simulant, Enhanced Mojave Mars Simulant, and Mars Global Simulant. The samples are prepared to have narrow particle-size distributions within the geometric-optics domain. We carry out laboratory measurements to obtain the particle-size distributions, shapes, and diffuse reflectance spectra of the Martian analogs deposited on a surface. Our model framework includes a ray-optics code to compute scattering properties for individual particles, and a radiative-transfer treatment to simulate the surface. The irregular shapes of the dust particles are taken into account in the model. We compare our derived imaginary parts of the refractive indices with those in the literature and find that they are much smaller than the ones that are commonly used for Martian dust. A sensitivity study shows that the retrieved optical constants are sensitive to the particle shape, which needs to be accounted for in applications that use different shapes. Finally, the derived values are validated by using them to reproduce the reflectance spectrum of the Martian surface regolith as observed by the Nadir and Occultation for Mars Discovery instrument on board the ExoMars mission.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136101498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-20DOI: 10.3847/1538-4365/acf3e3
Dejian Liu, Ye Xu, Chaojie Hao, Shuaibo Bian, Zehao Lin, Yingjie Li, Jingjing Li
Abstract Using young open clusters and O–B2-type stars in Gaia Data Release 3, we investigate the kinematics of the local spiral structure. In general, the young sources in the outer spiral arms may present larger peculiar motions than those in the inner spiral arms. The young open clusters appear to have smaller peculiar motions than the O–B2-type stars, and the sources in both the Perseus and Local Arms may show an inward motion toward the Galactic center and rotate slower than Galactic rotation. Meanwhile, the sources in the Carina Arm may move in the opposite direction from the Sun to the Galactic center and rotate marginally faster than Galactic rotation. In addition, using young open clusters and O–B2-type stars, we have improved the distance estimations of kinematic methods for several regions near the Sun.
{"title":"Kinematics of the Local Spiral Structure Revealed by Young Stars in Gaia DR3","authors":"Dejian Liu, Ye Xu, Chaojie Hao, Shuaibo Bian, Zehao Lin, Yingjie Li, Jingjing Li","doi":"10.3847/1538-4365/acf3e3","DOIUrl":"https://doi.org/10.3847/1538-4365/acf3e3","url":null,"abstract":"Abstract Using young open clusters and O–B2-type stars in Gaia Data Release 3, we investigate the kinematics of the local spiral structure. In general, the young sources in the outer spiral arms may present larger peculiar motions than those in the inner spiral arms. The young open clusters appear to have smaller peculiar motions than the O–B2-type stars, and the sources in both the Perseus and Local Arms may show an inward motion toward the Galactic center and rotate slower than Galactic rotation. Meanwhile, the sources in the Carina Arm may move in the opposite direction from the Sun to the Galactic center and rotate marginally faster than Galactic rotation. In addition, using young open clusters and O–B2-type stars, we have improved the distance estimations of kinematic methods for several regions near the Sun.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136308086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2023-09-20DOI: 10.3847/1538-4365/acee00
ZiQian 自乾 Shang 尚, Zhao 昭 Wu 武, Yan 岩 Liu 刘, Yu 宇 Bai 白, Guang 光 Lu 路, YuanYuan 园园 Zhang 张, Lei 磊 Zhang 张, YanRui 艳蕊 Su 苏, Yao 耀 Chen 陈, FaBao 发宝 Yan 严
Abstract Calibrating solar radio flux has always been a concern in the solar community. Previously, fluxes were calibrated by matching load or the new Moon for relative calibration, and at times with the assistance of other stations’ data. Moreover, the frequency coverage seldom exceeded 26 GHz. This paper reports the upgraded and calibrated Chashan Broadband Solar millimeter spectrometer (CBS) working from 35 to 40 GHz at the Chashan Solar Observatory (CSO). Initially, the calibration of the solar radiation brightness temperature is accomplished using the new Moon as the definitive source. Subsequently, the 35–40 GHz standard flux is achieved by establishing the correlation between the solar radio flux, brightness temperature, and frequency. Finally, the calibration of the solar radio flux is implemented by utilizing a constant temperature-controlled noise source as a reference. The calibration in 2023 February and March reveals that the solar brightness temperature is 11,636 K at 37.25 GHz with a standard deviation (STD) of 652 K. The solar radio flux’s intensity is ∼3000–4000 solar flux units (SFU) in the range of 35–40 GHz with a consistency bias of ±5.3%. The system sensitivity is about ∼5–8 SFU by a rough evaluation, a noise factor of about 200 K, and the coefficient of variation of the system transmission slope of 6.5% @ 12 hr at 37.25 GHz. It is expected that the upgraded CBS will capture more activity during the upcoming solar cycle.
{"title":"The Calibration of the 35–40 GHz Solar Radio Spectrometer with the New Moon and a Noise Source","authors":"ZiQian 自乾 Shang 尚, Zhao 昭 Wu 武, Yan 岩 Liu 刘, Yu 宇 Bai 白, Guang 光 Lu 路, YuanYuan 园园 Zhang 张, Lei 磊 Zhang 张, YanRui 艳蕊 Su 苏, Yao 耀 Chen 陈, FaBao 发宝 Yan 严","doi":"10.3847/1538-4365/acee00","DOIUrl":"https://doi.org/10.3847/1538-4365/acee00","url":null,"abstract":"Abstract Calibrating solar radio flux has always been a concern in the solar community. Previously, fluxes were calibrated by matching load or the new Moon for relative calibration, and at times with the assistance of other stations’ data. Moreover, the frequency coverage seldom exceeded 26 GHz. This paper reports the upgraded and calibrated Chashan Broadband Solar millimeter spectrometer (CBS) working from 35 to 40 GHz at the Chashan Solar Observatory (CSO). Initially, the calibration of the solar radiation brightness temperature is accomplished using the new Moon as the definitive source. Subsequently, the 35–40 GHz standard flux is achieved by establishing the correlation between the solar radio flux, brightness temperature, and frequency. Finally, the calibration of the solar radio flux is implemented by utilizing a constant temperature-controlled noise source as a reference. The calibration in 2023 February and March reveals that the solar brightness temperature is 11,636 K at 37.25 GHz with a standard deviation (STD) of 652 K. The solar radio flux’s intensity is ∼3000–4000 solar flux units (SFU) in the range of 35–40 GHz with a consistency bias of ±5.3%. The system sensitivity is about ∼5–8 SFU by a rough evaluation, a noise factor of about 200 K, and the coefficient of variation of the system transmission slope of 6.5% @ 12 hr at 37.25 GHz. It is expected that the upgraded CBS will capture more activity during the upcoming solar cycle.","PeriodicalId":8588,"journal":{"name":"Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136308082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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