The Gravitational wave burst high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a dedicated mission for monitoring the high-energy transients. Here we report the design of the GECAM Scientific Ground Segment (GSGS) in terms of the scientific requirements, including the architecture, the external interfaces, the main function and workflow. Judging from the analysis and verification results during the commissioning phase, the GSGS functions well and is able to monitor the status of the payloads, adjust the parameters, develop the scientific observation plans, generate the scientific data products, and analyze the data, etc. Thus, the on-orbit operation and scientific researches of GECAM are guaranteed.
{"title":"The design of GECAM Scientific Ground Segment","authors":"Shijie Zheng, Liming Song, Xiang Ma, Ping Wang, Rui Qiao, Yue Huang, Xiao-Yun Zhao, Hongmei Zhang, Xiaobo Li, Shaolin Xiong","doi":"10.1088/1674-4527/ad683a","DOIUrl":"https://doi.org/10.1088/1674-4527/ad683a","url":null,"abstract":"\u0000 The Gravitational wave burst high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a dedicated mission for monitoring the high-energy transients. Here we report the design of the GECAM Scientific Ground Segment (GSGS) in terms of the scientific requirements, including the architecture, the external interfaces, the main function and workflow. Judging from the analysis and verification results during the commissioning phase, the GSGS functions well and is able to monitor the status of the payloads, adjust the parameters, develop the scientific observation plans, generate the scientific data products, and analyze the data, etc. Thus, the on-orbit operation and scientific researches of GECAM are guaranteed.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"76 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141798372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-27DOI: 10.1088/1674-4527/ad683d
Hai-Long Huang, Yong Cai, Jun-Qian Jiang, Jun Zhang, Yun-song Piao
Recently, observational hints for supermassive black holes have been accumulating, prompting the question: Can primordial black holes (PBHs) be supermassive, particularly with masses $Mgtrsim 10^{9}M_odot$? A supercritical bubble, containing an inflating baby universe, that nucleated during inflation can evolve into a PBH in our observable Universe. We find that when the inflaton slowly transitions past a neighboring vacuum, the nucleation rate of supercritical bubbles inevitably peaks, leading to a mass distribution of multiverse PBHs with a peak mass up to $Mgtrsim 10^{11}M_odot$. Thus, our mechanism naturally provides a primordial origin for supermassive black holes.
{"title":"Supermassive primordial black holes for nano-Hertz gravitational waves and high-redshift JWST galaxies","authors":"Hai-Long Huang, Yong Cai, Jun-Qian Jiang, Jun Zhang, Yun-song Piao","doi":"10.1088/1674-4527/ad683d","DOIUrl":"https://doi.org/10.1088/1674-4527/ad683d","url":null,"abstract":"\u0000 Recently, observational hints for supermassive black holes have been accumulating, prompting the question: Can primordial black holes (PBHs) be supermassive, particularly with masses $Mgtrsim 10^{9}M_odot$? A supercritical bubble, containing an inflating baby universe, that nucleated during inflation can evolve into a PBH in our observable Universe. We find that when the inflaton slowly transitions past a neighboring vacuum, the nucleation rate of supercritical bubbles inevitably peaks, leading to a mass distribution of multiverse PBHs with a peak mass up to $Mgtrsim 10^{11}M_odot$. Thus, our mechanism naturally provides a primordial origin for supermassive black holes.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"5 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141797349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-16DOI: 10.1088/1674-4527/ad63e6
A. Al Zahrani, Ahmad Al-Jamaa
We study the capture cross-section of charged particles by a weakly charged Schwarzschild black hole. The dependence of the maximum impact parameter for capture on the particle's energy is investigated numerically for different values of the electromagnetic coupling strength between the particle and the black hole. The capture cross-section is then calculated. We show that the capture cross-section is independent of the electromagnetic coupling for ultra-relativistic particles. The astrophysical implications of our results are discussed.
{"title":"Charged Particles Capture Cross-Section by a Weakly Charged Schwarzschild Black Hole","authors":"A. Al Zahrani, Ahmad Al-Jamaa","doi":"10.1088/1674-4527/ad63e6","DOIUrl":"https://doi.org/10.1088/1674-4527/ad63e6","url":null,"abstract":"\u0000 We study the capture cross-section of charged particles by a weakly charged Schwarzschild black hole. The dependence of the maximum impact parameter for capture on the particle's energy is investigated numerically for different values of the electromagnetic coupling strength between the particle and the black hole. The capture cross-section is then calculated. We show that the capture cross-section is independent of the electromagnetic coupling for ultra-relativistic particles. The astrophysical implications of our results are discussed.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"17 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141641935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1088/1674-4527/ad6350
Xuan Zhang, Jin-Zhong Liu, Letian Wang
In this work, we report observations of three comets: 38P/Stephan-Oterma, 64P/Swift-Gehrels, and C/2017 M4 (ATLAS), conducted with the Nanshan one-meter wide- field telescope in August and November 2018, and January 2019. We extracted morphological features through image enhancement techniques and calculated the dust activity parameter, Afρ, along with dust mass loss rates and coma color indices using broadband photometric data. Our morphological analysis uncovered a spectrum of dust characteristics among the ob- served comets, ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/Swift-Gehrels. The Afρ values varied between 148.8 ± 0.3 cm for 64P/Swift-Gehrels and 1118.5 ± 6.2 cm for C/2017 M4 (ATLAS) (measured within a reference aperture radius of ρ = 6 arcsec), indicating a range from moderate to high activity levels. Dust mass loss rates were estimated from 328.1 kg/s for comet 64P/Swift-Gehrels to 1395.5 kg/s for comet C/2017 M4 (ATLAS). The color indices of comets 38P/Stephan-Oterma and C/2017 M4 (ATLAS) closely resemble the average col- ors of active short-period comets (SPCs) and active long-period comets (LPCs), respectively. In contrast, 64P/Swift-Gehrels exhibit a significantly bluer hue than typical Jupiter Family Comets (JFCs).
{"title":"Understanding the activity performance of comets 38P/Stephan-Oterma, 64P/Swift-Gehrels and C/2017 M4 (ATLAS) through broadband photometric observations","authors":"Xuan Zhang, Jin-Zhong Liu, Letian Wang","doi":"10.1088/1674-4527/ad6350","DOIUrl":"https://doi.org/10.1088/1674-4527/ad6350","url":null,"abstract":"\u0000 In this work, we report observations of three comets: 38P/Stephan-Oterma, 64P/Swift-Gehrels, and C/2017 M4 (ATLAS), conducted with the Nanshan one-meter wide- field telescope in August and November 2018, and January 2019. We extracted morphological features through image enhancement techniques and calculated the dust activity parameter, Afρ, along with dust mass loss rates and coma color indices using broadband photometric data. Our morphological analysis uncovered a spectrum of dust characteristics among the ob- served comets, ranging from a significant twisted structure in comet 38P/Stephan-Oterma’s coma to the regular coma envelope surrounding comet 64P/Swift-Gehrels. The Afρ values varied between 148.8 ± 0.3 cm for 64P/Swift-Gehrels and 1118.5 ± 6.2 cm for C/2017 M4 (ATLAS) (measured within a reference aperture radius of ρ = 6 arcsec), indicating a range from moderate to high activity levels. Dust mass loss rates were estimated from 328.1 kg/s for comet 64P/Swift-Gehrels to 1395.5 kg/s for comet C/2017 M4 (ATLAS). The color indices of comets 38P/Stephan-Oterma and C/2017 M4 (ATLAS) closely resemble the average col- ors of active short-period comets (SPCs) and active long-period comets (LPCs), respectively. In contrast, 64P/Swift-Gehrels exhibit a significantly bluer hue than typical Jupiter Family Comets (JFCs).","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":" 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141833449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
X-ray observations play a crucial role in time-domain astronomy. The Einstein Probe (EP), a recently launched X-ray astronomical satellite, emerges as a forefront player in the field of time-domain astronomy and high-energy astrophysics. With a focus on sys tematic surveys in the soft X-ray band, EP aims to discover high-energy transients and monitor variable sources in the universe. To achieve these objectives, a quick and reli able classification of observed sources is essential. In this study, we developed a machine learning classifier for autonomous source classification using data from the EP-WXT Pathfinder - Lobster Eye Imager for Astronomy (LEIA) and EP-WXT simulations. The proposed random forest classifier, built on selected features derived from light curves, en ergy spectra, and location information, achieves an accuracy of approximately 95% on EP simulation data and 98% on LEIA observational data. The classifier is integrated into the LEIA data processing pipeline, serving as a tool for manual validation and rapid classifi cation during observations. This paper presents an efficient method for the classification of X-ray sources based on single observations, along with implications of most effective features for the task. This work facilitates rapid source classification for the EP mission and also provides valuable insights into feature selection and classification techniques for enhancing the efficiency and accuracy of X-ray source classification that can be adapted to other X-ray telescope data.
X 射线观测在时域天文学中发挥着至关重要的作用。爱因斯坦探测器（EP）是最近发射的一颗 X 射线天文卫星，是时域天文学和高能天体物理学领域的先驱。EP 的重点是软 X 射线波段的系统测量，旨在发现高能瞬态并监测宇宙中的可变源。要实现这些目标，必须对观测到的源进行快速可靠的分类。在这项研究中，我们利用来自 EP-WXT 探路者--龙虾眼天文成像仪（LEIA）和 EP-WXT 模拟的数据，开发了一种用于自主源分类的机器学习分类器。所提出的随机森林分类器基于从光曲线、能谱和位置信息中选取的特征，在 EP 模拟数据和 LEIA 观测数据上分别达到了约 95% 和 98% 的准确率。该分类器被集成到 LEIA 数据处理管道中，作为观测过程中手动验证和快速分类的工具。本文介绍了一种基于单次观测数据对 X 射线源进行分类的高效方法，以及该任务最有效特征的含义。这项工作为 EP 任务的快速源分类提供了便利，也为提高 X 射线源分类的效率和准确性的特征选择和分类技术提供了有价值的见解，可适用于其他 X 射线望远镜数据。
{"title":"X-ray Sources Classification Using Machine Learning: A Study with EP-WXT Pathfinder LEIA","authors":"Xiaoxiong Zuo, Yihan Tao, Yuan Liu, Yunfei Xu, Wenda Zhang, Haiwu Pan, Hui Sun, Zhen Zhang, Chenzhou Cui, W. Yuan","doi":"10.1088/1674-4527/ad634f","DOIUrl":"https://doi.org/10.1088/1674-4527/ad634f","url":null,"abstract":"\u0000 X-ray observations play a crucial role in time-domain astronomy. The Einstein Probe (EP), a recently launched X-ray astronomical satellite, emerges as a forefront player in the field of time-domain astronomy and high-energy astrophysics. With a focus on sys tematic surveys in the soft X-ray band, EP aims to discover high-energy transients and monitor variable sources in the universe. To achieve these objectives, a quick and reli able classification of observed sources is essential. In this study, we developed a machine learning classifier for autonomous source classification using data from the EP-WXT Pathfinder - Lobster Eye Imager for Astronomy (LEIA) and EP-WXT simulations. The proposed random forest classifier, built on selected features derived from light curves, en ergy spectra, and location information, achieves an accuracy of approximately 95% on EP simulation data and 98% on LEIA observational data. The classifier is integrated into the LEIA data processing pipeline, serving as a tool for manual validation and rapid classifi cation during observations. This paper presents an efficient method for the classification of X-ray sources based on single observations, along with implications of most effective features for the task. This work facilitates rapid source classification for the EP mission and also provides valuable insights into feature selection and classification techniques for enhancing the efficiency and accuracy of X-ray source classification that can be adapted to other X-ray telescope data.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"100 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141647164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1088/1674-4527/ad634e
Mamatha Rani Gaddam, K. Sriram, Deblina Lahiri, Vijaya Annemalla
Contact binaries at various stages of evolution unveil various operating mechanism that drives them. We report the photometric and period variations analysis of two contact binaries EV Cnc and AH Cnc in open cluster M 67. We observed the cluster from the JCBT 1.3 m telescope and utilized TESS and Kepler observations. The photometric solutions of EV Cnc and AH Cnc revealed a mass ratio of q$sim$0.40 & $sim$0.15 with an inclination of i=42$^{circ}$ & 87$^{circ}$. These solutions suggest that EV Cnc is probably a marginal contact binary and AH Cnc is a deep low mass ratio contact binary. The study of O-C variation analysis indicates that for both the systems, the period is increasing which suggests the mass transfer is occurring from secondary to primary. In the case of AH Cnc and based on simulations by randomly varying the time of minima to fit the LITE solution, we noted the third body orbital period to be around P$_{3}$ = 26.82 $pm$ 2.54 years, which is different from earlier reported values and conclude that future observations are required to confirm this scenario. We compare these two systems with other similar contact binaries to get an estimate of the final configuration of the respective systems.
{"title":"Photometric studies of EV Cnc and AH Cnc in the open cluster M 67","authors":"Mamatha Rani Gaddam, K. Sriram, Deblina Lahiri, Vijaya Annemalla","doi":"10.1088/1674-4527/ad634e","DOIUrl":"https://doi.org/10.1088/1674-4527/ad634e","url":null,"abstract":"\u0000 Contact binaries at various stages of evolution unveil various operating mechanism that drives them. We report the photometric and period variations analysis of two contact binaries EV Cnc and AH Cnc in open cluster M 67. We observed the cluster from the JCBT 1.3 m telescope and utilized TESS and Kepler observations. The photometric solutions of EV Cnc and AH Cnc revealed a mass ratio of q$sim$0.40 & $sim$0.15 with an inclination of i=42$^{circ}$ & 87$^{circ}$. These solutions suggest that EV Cnc is probably a marginal contact binary and AH Cnc is a deep low mass ratio contact binary. The study of O-C variation analysis indicates that for both the systems, the period is increasing which suggests the mass transfer is occurring from secondary to primary. In the case of AH Cnc and based on simulations by randomly varying the time of minima to fit the LITE solution, we noted the third body orbital period to be around P$_{3}$ = 26.82 $pm$ 2.54 years, which is different from earlier reported values and conclude that future observations are required to confirm this scenario. We compare these two systems with other similar contact binaries to get an estimate of the final configuration of the respective systems.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"35 37","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141645658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-11DOI: 10.1088/1674-4527/ad621e
Jun Yao, Jia-cheng Liu, Niu Liu, Zi Zhu, Zhen-Wei Wang
The multi-color imaging sky survey conducted by the China Space Station Telescope (CSST) holds significant promise for advancing the development of the celestial reference frame. In this study, we focus on assessing the astrometric performance of the CSST celestial reference frame (CSST-CRF) in extending the Gaia Celestial Reference Frame 3 (Gaia-CRF3). Firstly, the orientation precision of the CSST reference frame is evaluated using a simulated set of extragalactic sources with CSST g magnitudes ranging from 18 to 25 mag. The estimated orientation uncertainty caused by random error insignificantly affects the alignment between Gaia-CRF3 and the CSST-CRF. Then, the systematic effect of incomplete CSST sky coverage on the alignment between CSST-CRF and Gaia-CRF3 is discussed by analyzing the differences between the subset of Gaia-CRF3 in the CSST observation region ($rm{Gaiambox{-}CRF3'}$) and Gaia-CRF3 as a whole. Using the third International Celestial Reference Frame (ICRF3) S/X band as an intermediate reference frame, the orientation offset between $rm{Gaiambox{-}CRF3'}$ and Gaia-CRF3 is estimated to be 20 $rm{mu as}$. This offset is marginally larger than the orientation offset between Gaia-CRF3 and the ICRF3, approximately 15 $rm{mu as}$. The residual spin and glide rate of $rm{Gaiambox{-}CRF3'}$ are derived from the proper motions, consistent with that of Gaia-CRF3 within the formal error. Finally, we explore the role of CSST in establishing a multi-band celestial reference frame by comparing its limiting magnitude and observation accuracy with existing catalogs in the infrared and ultraviolet bands. Thanks to its broad wavelength coverage and high-precision measurements, CSST is well-positioned to make significant contributions to the development of a multi-band celestial reference frame.
{"title":"The Astrometric Performance of the China Space Station Telescope (CSST) Sky Survey in Extending the Gaia Celestial Reference Frame","authors":"Jun Yao, Jia-cheng Liu, Niu Liu, Zi Zhu, Zhen-Wei Wang","doi":"10.1088/1674-4527/ad621e","DOIUrl":"https://doi.org/10.1088/1674-4527/ad621e","url":null,"abstract":"\u0000 The multi-color imaging sky survey conducted by the China Space Station Telescope (CSST) holds significant promise for advancing the development of the celestial reference frame. In this study, we focus on assessing the astrometric performance of the CSST celestial reference frame (CSST-CRF) in extending the Gaia Celestial Reference Frame 3 (Gaia-CRF3). Firstly, the orientation precision of the CSST reference frame is evaluated using a simulated set of extragalactic sources with CSST g magnitudes ranging from 18 to 25 mag. The estimated orientation uncertainty caused by random error insignificantly affects the alignment between Gaia-CRF3 and the CSST-CRF. Then, the systematic effect of incomplete CSST sky coverage on the alignment between CSST-CRF and Gaia-CRF3 is discussed by analyzing the differences between the subset of Gaia-CRF3 in the CSST observation region ($rm{Gaiambox{-}CRF3'}$) and Gaia-CRF3 as a whole. Using the third International Celestial Reference Frame (ICRF3) S/X band as an intermediate reference frame, the orientation offset between $rm{Gaiambox{-}CRF3'}$ and Gaia-CRF3 is estimated to be 20 $rm{mu as}$. This offset is marginally larger than the orientation offset between Gaia-CRF3 and the ICRF3, approximately 15 $rm{mu as}$. The residual spin and glide rate of $rm{Gaiambox{-}CRF3'}$ are derived from the proper motions, consistent with that of Gaia-CRF3 within the formal error. Finally, we explore the role of CSST in establishing a multi-band celestial reference frame by comparing its limiting magnitude and observation accuracy with existing catalogs in the infrared and ultraviolet bands. Thanks to its broad wavelength coverage and high-precision measurements, CSST is well-positioned to make significant contributions to the development of a multi-band celestial reference frame.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"27 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141658702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We analyze the frequencies of three known roAp stars, TIC 96315731, TIC 72392575, and TIC 318007796, using the light curves from the Transiting Exoplanet Survey Satellite (TESS). For TIC 96315731, the rotational and pulsational frequencies are 0.1498360 d-1 and 165.2609 d-1, respectively. In the case of TIC 72392575, the rotational frequency is 0.25551 d-1. We detect a quintuplet of pulsation frequencies with a center frequency of 135.9233 d-1, along with two signals within the second pair of rotational sidelobes of the quintuplet separated by the rotation frequency. These two signals may correspond to the frequencies of a dipole mode. In TIC 318007796, the rotational and pulsational frequencies are 0.2475021 d-1, 192.73995 d-1, and 196.33065 d-1, respectively. Based on the oblique pulsator model, we calculate the rotation inclination (i) and magnetic obliquity angle (β) for the stars, which provides the geometry of the pulsation modes. Combining the phases of the frequency quintuplets, the pulsation amplitude and phase modulation curves, and the results of spherical harmonic decomposition, we conclude that the pulsation modes of frequency quintuplets in TIC 96315731, TIC 72392575, and TIC 318007796 correspond to distorted dipole mode, distorted quadrupole mode, and distorted dipole mode, respectively.
{"title":"Pulsations of Three Rapidly Oscillating Ap Stars TIC 96315731, TIC 72392575, and TIC 318007796","authors":"Haijian Zhong, Dongxiang Shen, Chun-Hua Zhu, He-Lei Liu, Sufen Guo, Guo-Liang lv","doi":"10.1088/1674-4527/ad621d","DOIUrl":"https://doi.org/10.1088/1674-4527/ad621d","url":null,"abstract":"\u0000 We analyze the frequencies of three known roAp stars, TIC 96315731, TIC 72392575, and TIC 318007796, using the light curves from the Transiting Exoplanet Survey Satellite (TESS). For TIC 96315731, the rotational and pulsational frequencies are 0.1498360 d-1 and 165.2609 d-1, respectively. In the case of TIC 72392575, the rotational frequency is 0.25551 d-1. We detect a quintuplet of pulsation frequencies with a center frequency of 135.9233 d-1, along with two signals within the second pair of rotational sidelobes of the quintuplet separated by the rotation frequency. These two signals may correspond to the frequencies of a dipole mode. In TIC 318007796, the rotational and pulsational frequencies are 0.2475021 d-1, 192.73995 d-1, and 196.33065 d-1, respectively. Based on the oblique pulsator model, we calculate the rotation inclination (i) and magnetic obliquity angle (β) for the stars, which provides the geometry of the pulsation modes. Combining the phases of the frequency quintuplets, the pulsation amplitude and phase modulation curves, and the results of spherical harmonic decomposition, we conclude that the pulsation modes of frequency quintuplets in TIC 96315731, TIC 72392575, and TIC 318007796 correspond to distorted dipole mode, distorted quadrupole mode, and distorted dipole mode, respectively.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"141 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141655985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-11DOI: 10.1088/1674-4527/ad621f
S. Wadhwa, Adam Popowicz, R. Michel, Petar Kosti´c, Oliver Vince, Nick F. H. Tothill, Ain Y. DeHorta, Miroslav Filipovic´
Low mass ratio contact binary systems are more likely to have unstable orbits and potentially merge. In addition, such systems exhibit characteristics such as starspots and high energy emissions (UV) suggestive of chromospheric and magnetic activity. Light curve modelling of ten contact binary systems is reported. All were found to be of extreme low mass ratio ranging from 0.122 to 0.24 and three were found to be potentially unstable and possible merger candidates. Filling of the infrared Calcium absorption lines is a marker of increased chromospheric activity. We use the available LAMOST spectra along with matched standard spectra (broadened for rotation) to measure the excess filling of the central core depression flux of the two main infrared Calcium absorption lines λ8542 and λ8662. We find that all reported contact binaries have excess filling of the core flux in the infrared Calcium lines. Three of the systems reported were also observed by the GALEX mission and we find that all three have features of excess ultraviolet emissions further adding evidence for increased chromospheric activity in low mass ratio contact binaries. Analysis of both orbital stability and absorption line filling is dependent on the determination of geometric and absolute parameters from light curve modelling. Not an insignificant number of contact binary light curves exhibit the O’Connell effect, usually attributed to starspots. We discuss the inclusion of starspots in light curve solutions and how they influence the geometric and absolute parameters.
{"title":"Photometric and Spectroscopic study of Ten Low Mass Ratio ContactBinary Systems: Orbital Stability, O’Connell Effect and Infra-redCalcium Line Filling.","authors":"S. Wadhwa, Adam Popowicz, R. Michel, Petar Kosti´c, Oliver Vince, Nick F. H. Tothill, Ain Y. DeHorta, Miroslav Filipovic´","doi":"10.1088/1674-4527/ad621f","DOIUrl":"https://doi.org/10.1088/1674-4527/ad621f","url":null,"abstract":"\u0000 Low mass ratio contact binary systems are more likely to have unstable orbits and potentially merge. In addition, such systems exhibit characteristics such as starspots and high energy emissions (UV) suggestive of chromospheric and magnetic activity. Light curve modelling of ten contact binary systems is reported. All were found to be of extreme low mass ratio ranging from 0.122 to 0.24 and three were found to be potentially unstable and possible merger candidates. Filling of the infrared Calcium absorption lines is a marker of increased chromospheric activity. We use the available LAMOST spectra along with matched standard spectra (broadened for rotation) to measure the excess filling of the central core depression flux of the two main infrared Calcium absorption lines λ8542 and λ8662. We find that all reported contact binaries have excess filling of the core flux in the infrared Calcium lines. Three of the systems reported were also observed by the GALEX mission and we find that all three have features of excess ultraviolet emissions further adding evidence for increased chromospheric activity in low mass ratio contact binaries. Analysis of both orbital stability and absorption line filling is dependent on the determination of geometric and absolute parameters from light curve modelling. Not an insignificant number of contact binary light curves exhibit the O’Connell effect, usually attributed to starspots. We discuss the inclusion of starspots in light curve solutions and how they influence the geometric and absolute parameters.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"91 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141657741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.1088/1674-4527/ad607d
Jiao Zheng, Peng-fei Zhang, Li Zhang
We report a gradual brightening γ-ray source, 4FGL J1718.5+4237, in 0.1– 500.0 GeV, which may be associated with a blazar NVSS J171822+423948 with a redshift of ~2.7. We analyzed 15.25 yr of γ-ray data recorded by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detected significant γ-ray emissions in the di- rection of the blazar with a test statistic (TS) of ~135. Based on timing analysis using a 1-year time bin, we have observed a gradual brightening γ-ray emissions from the target. In our analysis, we categorize them into two states: Quiet (TS~0) and Loud (TS~226) states, with the distinction occurring in August 2016 (MJD 57602.69). From the Quiet state to the brightest period (the last data point), the γ-ray flux in the 0.1–500.0 GeV increased by more than 12-fold from <0.2×10−8 photons cm−1 s−1 to 2.6×10−8 photons cm−1 s−1. Additionally, we studied the spectral properties in detail for the Loud state and the overall data. While no significant variation was detected, both exhibited a spectral index Γ of ~2.6. The origin of the brightening γ-ray emissions from the target is not yet clear. Future long-term multi- wavelength observations and studies will provide insight into the astrophysical mechanisms of the target.
{"title":"Detection of Increasing Gamma-ray Emissions from 4FGL J1718.5+4237 with Fermi-LAT","authors":"Jiao Zheng, Peng-fei Zhang, Li Zhang","doi":"10.1088/1674-4527/ad607d","DOIUrl":"https://doi.org/10.1088/1674-4527/ad607d","url":null,"abstract":"\u0000 We report a gradual brightening γ-ray source, 4FGL J1718.5+4237, in 0.1– 500.0 GeV, which may be associated with a blazar NVSS J171822+423948 with a redshift of ~2.7. We analyzed 15.25 yr of γ-ray data recorded by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detected significant γ-ray emissions in the di- rection of the blazar with a test statistic (TS) of ~135. Based on timing analysis using a 1-year time bin, we have observed a gradual brightening γ-ray emissions from the target. In our analysis, we categorize them into two states: Quiet (TS~0) and Loud (TS~226) states, with the distinction occurring in August 2016 (MJD 57602.69). From the Quiet state to the brightest period (the last data point), the γ-ray flux in the 0.1–500.0 GeV increased by more than 12-fold from <0.2×10−8 photons cm−1 s−1 to 2.6×10−8 photons cm−1 s−1. Additionally, we studied the spectral properties in detail for the Loud state and the overall data. While no significant variation was detected, both exhibited a spectral index Γ of ~2.6. The origin of the brightening γ-ray emissions from the target is not yet clear. Future long-term multi- wavelength observations and studies will provide insight into the astrophysical mechanisms of the target.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"109 45","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141665867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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