Pub Date : 2024-05-06DOI: 10.1088/1674-4527/ad47de
Lei Xing, Jianheng Guo, Chuyuan Yang, Dongdong Yan
Observations of transmission spectra reveal that hot Jupiters and Neptunes are likely to possess escaping atmospheres driven by stellar radiation. Numerous models predict that magnetic fields may exert significant influences on the atmospheres of hot planets. Generally, the escaping atmospheres are not entirely ionized, and magnetic fields only directly affect the escape of ionized components within them. Considering the chemical reactions between ionized components and neutral atoms, as well as collision processes, magnetic fields indirectly impact the escape of neutral atoms, thereby influencing the detection signals of planetary atmospheres in transmission spectra. In order to simulate this process, we developed a magneto-hydrodynamic multi-fluid model based on MHD code PLUTO. As an initial exploration, we investigated the impact of magnetic fields on the decoupling of H+ and H in the escaping atmosphere of the hot Neptune GJ436 b. Due to the strong resonant interactions between H and H+ , the coupling between them is tight even if the magnetic field is strong. Of course, alternatively, our work also suggests that merging H and H+ into a single flow can be a reasonable assumption in MHD simulations of escaping atmospheres. However, our simulation results indicate that under the influence of magnetic fields, there are noticeable regional differences in the decoupling of H+ and H. With the increase of magnetic field strength, the degree of decoupling also increases. For heavier particles such as O, the decoupling between O and H+ is more pronounced. Our findings provide important insights for future studies on the decoupling processes of heavy atoms in the escaping atmospheres of hot Jupiters and hot Neptunes under the influence of magnetic fields.
对透射光谱的观测表明，热木星和海王星很可能拥有由恒星辐射驱动的逃逸大气层。许多模型预测，磁场可能会对热行星的大气层产生重大影响。一般来说，逸出大气并非完全电离，磁场只会直接影响其中电离成分的逸出。考虑到电离成分和中性原子之间的化学反应以及碰撞过程，磁场会间接影响中性原子的逸出，从而影响透射光谱中行星大气的探测信号。为了模拟这一过程，我们在 MHD 代码 PLUTO 的基础上开发了磁流体动力学多流体模型。作为初步探索，我们研究了磁场对热海王星 GJ436 b 逸出大气中 H+ 和 H 解耦的影响。当然，我们的工作也表明，在逸出大气的 MHD 模拟中，将 H 和 H+ 合并成单一气流也是一个合理的假设。然而，我们的模拟结果表明，在磁场的影响下，H+ 和 H 的解耦存在明显的区域差异。对于 O 等较重的粒子，O 和 H+ 之间的解耦更为明显。我们的发现为今后研究热木星和热海王星逸出大气中重原子在磁场影响下的解耦过程提供了重要启示。
{"title":"Simulating the Escaping Atmosphere of GJ436 b with two-fluid Magnetohydrodynamic Models","authors":"Lei Xing, Jianheng Guo, Chuyuan Yang, Dongdong Yan","doi":"10.1088/1674-4527/ad47de","DOIUrl":"https://doi.org/10.1088/1674-4527/ad47de","url":null,"abstract":"\u0000 Observations of transmission spectra reveal that hot Jupiters and Neptunes are likely to possess escaping atmospheres driven by stellar radiation. Numerous models predict that magnetic fields may exert significant influences on the atmospheres of hot planets. Generally, the escaping atmospheres are not entirely ionized, and magnetic fields only directly affect the escape of ionized components within them. Considering the chemical reactions between ionized components and neutral atoms, as well as collision processes, magnetic fields indirectly impact the escape of neutral atoms, thereby influencing the detection signals of planetary atmospheres in transmission spectra. In order to simulate this process, we developed a magneto-hydrodynamic multi-fluid model based on MHD code PLUTO. As an initial exploration, we investigated the impact of magnetic fields on the decoupling of H+ and H in the escaping atmosphere of the hot Neptune GJ436 b. Due to the strong resonant interactions between H and H+ , the coupling between them is tight even if the magnetic field is strong. Of course, alternatively, our work also suggests that merging H and H+ into a single flow can be a reasonable assumption in MHD simulations of escaping atmospheres. However, our simulation results indicate that under the influence of magnetic fields, there are noticeable regional differences in the decoupling of H+ and H. With the increase of magnetic field strength, the degree of decoupling also increases. For heavier particles such as O, the decoupling between O and H+ is more pronounced. Our findings provide important insights for future studies on the decoupling processes of heavy atoms in the escaping atmospheres of hot Jupiters and hot Neptunes under the influence of magnetic fields.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"38 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141009366","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}
Recent Submillimeter dust thermal emission observations have unveiled a significant number of inter-arm massive molecular clouds in M31. However, the effectiveness of this technique is limited to its sensitivity, making it challenging to study more distant galaxies. This study introduces an alternative approach, utilizing optical extinctions derived from space-based telescopes, with a focus on the forthcoming China Space Station Telescope (CSST). We first demonstrate the capability of this method by constructing dust extinction maps for 17 inter-arm massive molecular clouds in M31 using the Panchromatic Hubble Andromeda Treasury (PHAT) data. Our analysis reveals that inter-arm massive molecular clouds with an optical extinction (AV) greater than 1.6 magnitudes exhibit a notable AV excess, facilitating their identification. The majority of these inter-arm massive molecular clouds show an AV around 1 magnitude, aligning with measurements from our JCMT data. Further validation using a mock CSST RGB star catalog confirms the method’s effectiveness. We show that the derived AV values using CSST z and y photometries align more closely with the input values. Molecular clouds with AV > 1.6 can also be identified using the CSST mock data. We thus claim that future CSST observation cloud provide an effective way for the detection of inter-arm massive molecular clouds with significant optical extinction in nearby galaxies.
最近的亚毫米波尘埃热辐射观测揭示了 M31 中大量的臂间大质量分子云。然而，这种技术的有效性受限于其灵敏度，因此对更遥远星系的研究具有挑战性。本研究介绍了另一种方法，即利用天基望远镜得出的光学衰减，重点是即将发射的中国空间站望远镜（CSST）。我们首先利用全色哈勃仙女座宝库（PHAT）数据为 M31 中的 17 个臂间大质量分子云绘制了尘埃消光图，展示了这种方法的能力。我们的分析表明，光消光（AV）大于 1.6 等的臂间大质量分子云表现出明显的光消光过量，这为识别它们提供了便利。这些臂间大质量分子云大多显示出 1 等左右的光消光，与 JCMT 数据的测量结果一致。使用模拟 CSST RGB 星表进行的进一步验证证实了该方法的有效性。我们表明，利用 CSST z 和 y 光度计得出的 AV 值与输入值更为接近。使用 CSST 模拟数据还可以识别出 AV > 1.6 的分子云。因此，我们认为未来的CSST观测云可以为探测附近星系中具有显著光学消光的臂间大质量分子云提供有效的方法。
{"title":"Optical Extinctions of Inter-Arm Molecular Clouds in M31: A Pilot Study for the Upcoming CSST Observations","authors":"Cailing Chen, Zheng Zheng, Chao-Wei Tsai, Sihan Jiao, Jing Tang, Jingwen Wu, Di Li, Yun Zheng, Linjing Feng, Yujiao Yang, Yuan Liang","doi":"10.1088/1674-4527/ad47dc","DOIUrl":"https://doi.org/10.1088/1674-4527/ad47dc","url":null,"abstract":"\u0000 Recent Submillimeter dust thermal emission observations have unveiled a significant number of inter-arm massive molecular clouds in M31. However, the effectiveness of this technique is limited to its sensitivity, making it challenging to study more distant galaxies. This study introduces an alternative approach, utilizing optical extinctions derived from space-based telescopes, with a focus on the forthcoming China Space Station Telescope (CSST). We first demonstrate the capability of this method by constructing dust extinction maps for 17 inter-arm massive molecular clouds in M31 using the Panchromatic Hubble Andromeda Treasury (PHAT) data. Our analysis reveals that inter-arm massive molecular clouds with an optical extinction (AV) greater than 1.6 magnitudes exhibit a notable AV excess, facilitating their identification. The majority of these inter-arm massive molecular clouds show an AV around 1 magnitude, aligning with measurements from our JCMT data. Further validation using a mock CSST RGB star catalog confirms the method’s effectiveness. We show that the derived AV values using CSST z and y photometries align more closely with the input values. Molecular clouds with AV > 1.6 can also be identified using the CSST mock data. We thus claim that future CSST observation cloud provide an effective way for the detection of inter-arm massive molecular clouds with significant optical extinction in nearby galaxies.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"58 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141008856","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 : 2024-05-01DOI: 10.1088/1674-4527/ad462c
Xiaohan Chen, Xiaodian Chen, Licai Deng, Shu Wang, Tianlu Chen
Long period variable stars (LPVs) are very promising distance indicators in the infrared bands. We selected asymptotic giant branch (AGB) stars in the Large and Small Magellanic Cloud (LMC and SMC) from the Gaia Data Release 3 (DR3) LPV catalog, and classified them into oxygen-rich (O-rich) and carbon-rich (C-rich) AGB stars. Using the WISE database, we determined the $W1$- and $W2$-bands Period--Luminosity relations (PLRs) for each pulsation-mode sequence of AGB stars. The dispersion of the PLRs of O-rich AGB stars in sequences $rm{C^{'}}$ and C is relatively small, around 0.14 mag. The PLRs of LMC and SMC are consistent in each sequence. % while due to selection effect, {bf the PLR zero points} of Milky Way are significantly underestimated. In the $W2$ band, the PLR of large-amplitude C-rich AGB stars is steeper than that of small-amplitude C-rich AGB stars, due to their more circumstellar dust. By two methods, we find that some PLR sequences of O-rich AGB stars in the LMC are dependent on metallicity. The coefficients of the metallicity effect are $beta = -0.533 pm 0.213 $ mag/dex and $beta= -0.767 pm 0.158$ mag/dex for sequence C in $W1$ and $W2$ bands, respectively. The significance of the metallicity effect in $W1$ band for the four sequences is $2.2-3.5 sigma$. Both of these imply that distance measurements using O-rich Mira maybe need to take the metallicity effect into account.
{"title":"Mid-infrared Period--Luminosity relations of Gaia DR3 Long Period Variables","authors":"Xiaohan Chen, Xiaodian Chen, Licai Deng, Shu Wang, Tianlu Chen","doi":"10.1088/1674-4527/ad462c","DOIUrl":"https://doi.org/10.1088/1674-4527/ad462c","url":null,"abstract":"\u0000 Long period variable stars (LPVs) are very promising distance indicators in the infrared bands. We selected asymptotic giant branch (AGB) stars in the Large and Small Magellanic Cloud (LMC and SMC) from the Gaia Data Release 3 (DR3) LPV catalog, and classified them into oxygen-rich (O-rich) and carbon-rich (C-rich) AGB stars. Using the WISE database, we determined the $W1$- and $W2$-bands Period--Luminosity relations (PLRs) for each pulsation-mode sequence of AGB stars. The dispersion of the PLRs of O-rich AGB stars in sequences $rm{C^{'}}$ and C is relatively small, around 0.14 mag. The PLRs of LMC and SMC are consistent in each sequence. % while due to selection effect, {bf the PLR zero points} of Milky Way are significantly underestimated. In the $W2$ band, the PLR of large-amplitude C-rich AGB stars is steeper than that of small-amplitude C-rich AGB stars, due to their more circumstellar dust. By two methods, we find that some PLR sequences of O-rich AGB stars in the LMC are dependent on metallicity. The coefficients of the metallicity effect are $beta = -0.533 pm 0.213 $ mag/dex and $beta= -0.767 pm 0.158$ mag/dex for sequence C in $W1$ and $W2$ bands, respectively. The significance of the metallicity effect in $W1$ band for the four sequences is $2.2-3.5 sigma$. Both of these imply that distance measurements using O-rich Mira maybe need to take the metallicity effect into account.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141026057","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 : 2024-03-20DOI: 10.1088/1674-4527/ad3618
Quan-Ling Cui, Chuan-peng Zhang, Junjie Wang
Infrared dust bubbles play an important role in the study of star formation and the evolution of the interstellar medium. In this work, we study the infrared dust bubble N75 and the infrared dark cloud G38.93 mainly using the tracers C 18 O, HCO + , HNC, and N 2 H + observed by the 30m IRAM telescope. We also study the targets using data from large-scale surveys: GLIMPSE, MIPSGAL, GRS, NVSS, and BGPS. We found that the C 18 O emission is morphologically similar to the Spitzer IRAC 8.0 µm emission. We also found that the YSOs are mainly located in the compressed regions between bubble N75 and G38.93, suggesting that expanding feedback could have triggered star formation. The dynamical age (∼ 5.1 × 10 5 yr) of the outflow is close to the expanding age (∼ 1.38 × 10 6 yr) of the bubble N75. It could be that they both formed in the same evolutionary period.
{"title":"Multiwavelength Observations of the Infrared Dust Bubble N75 and its Surroundings","authors":"Quan-Ling Cui, Chuan-peng Zhang, Junjie Wang","doi":"10.1088/1674-4527/ad3618","DOIUrl":"https://doi.org/10.1088/1674-4527/ad3618","url":null,"abstract":"\u0000 Infrared dust bubbles play an important role in the study of star formation and the evolution of the interstellar medium. In this work, we study the infrared dust bubble N75 and the infrared dark cloud G38.93 mainly using the tracers C 18 O, HCO + , HNC, and N 2 H + observed by the 30m IRAM telescope. We also study the targets using data from large-scale surveys: GLIMPSE, MIPSGAL, GRS, NVSS, and BGPS. We found that the C 18 O emission is morphologically similar to the Spitzer IRAC 8.0 µm emission. We also found that the YSOs are mainly located in the compressed regions between bubble N75 and G38.93, suggesting that expanding feedback could have triggered star formation. The dynamical age (∼ 5.1 × 10 5 yr) of the outflow is close to the expanding age (∼ 1.38 × 10 6 yr) of the bubble N75. It could be that they both formed in the same evolutionary period.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"4 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140225582","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 : 2024-03-19DOI: 10.1088/1674-4527/ad359a
Hai-Yang Mu, Zhou Fan, Yinan Zhu, Yu Zhang, Hong Wu
This work shows details of an evaluation of an observational system comprising a CMOS detector, 60-cm telescope, and filter complement. The system's photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of supersky flat fields, open clusters, standard stars, and exoplanets. Photometry was precision achieved at the 0.02 mag level, while differential photometry of 0.003 mag precision. Extinction was found to be agreed with previous studies conducted at Xinglong Observatory. Ultimately, the results demonstrate this observing system is capable of precision scientific observations with CCD across the optical wavelengths.
{"title":"Astronomical Test with CMOS on the 60-cm Telescope at the Xinglong Observatory, NAOC","authors":"Hai-Yang Mu, Zhou Fan, Yinan Zhu, Yu Zhang, Hong Wu","doi":"10.1088/1674-4527/ad359a","DOIUrl":"https://doi.org/10.1088/1674-4527/ad359a","url":null,"abstract":"\u0000 This work shows details of an evaluation of an observational system comprising a CMOS detector, 60-cm telescope, and filter complement. The system's photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of supersky flat fields, open clusters, standard stars, and exoplanets. Photometry was precision achieved at the 0.02 mag level, while differential photometry of 0.003 mag precision. Extinction was found to be agreed with previous studies conducted at Xinglong Observatory. Ultimately, the results demonstrate this observing system is capable of precision scientific observations with CCD across the optical wavelengths.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"18 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140230820","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 : 2024-03-17DOI: 10.1088/1674-4527/ad34bb
Yong-Xiong Zhang, Wen-Xiu Guo, Xiao-Ping Lu, Hua Zheng, Hai-bin Zhao, Jun Tian, Wei-Lin Wang
Determining asteroid properties provides valuable physical insights but inverting them from photometric lightcurves remains computationally intensive. This paper presents a new approach that combines a simplified Cellinoid shape model with the Parallel Differential Evolution (PDE) algorithm to accelerate inversion. The PDE algorithm is more efficient than the Differential Evolution (DE) algorithm, achieving an extraordinary speedup of 37.983 with 64 workers on multicore CPUs. The PDE algorithm accurately derives period and pole values from simulated data. The analysis of real asteroid lightcurves validates the method's reliability: in comparison with results published elsewhere, the PDE algorithm accurately recovers the rotational periods and, given adequate viewing geometries, closely matches the pole orientations. The PDE approach converges to solutions within 20,000 iterations and under one hour, demonstrating its potential for large-scale data analysis. This work provides a promising new tool for unveiling asteroid physical properties by overcoming key computational bottlenecks.
{"title":"Accelerating Asteroidal Period and Pole Inversion from Multiple Lightcurves Using Parallel Differential Evolution and Cellinoid Shape Model","authors":"Yong-Xiong Zhang, Wen-Xiu Guo, Xiao-Ping Lu, Hua Zheng, Hai-bin Zhao, Jun Tian, Wei-Lin Wang","doi":"10.1088/1674-4527/ad34bb","DOIUrl":"https://doi.org/10.1088/1674-4527/ad34bb","url":null,"abstract":"\u0000 Determining asteroid properties provides valuable physical insights but inverting them from photometric lightcurves remains computationally intensive. This paper presents a new approach that combines a simplified Cellinoid shape model with the Parallel Differential Evolution (PDE) algorithm to accelerate inversion. The PDE algorithm is more efficient than the Differential Evolution (DE) algorithm, achieving an extraordinary speedup of 37.983 with 64 workers on multicore CPUs. The PDE algorithm accurately derives period and pole values from simulated data. The analysis of real asteroid lightcurves validates the method's reliability: in comparison with results published elsewhere, the PDE algorithm accurately recovers the rotational periods and, given adequate viewing geometries, closely matches the pole orientations. The PDE approach converges to solutions within 20,000 iterations and under one hour, demonstrating its potential for large-scale data analysis. This work provides a promising new tool for unveiling asteroid physical properties by overcoming key computational bottlenecks.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"84 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140234970","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 : 2024-03-15DOI: 10.1088/1674-4527/ad349a
Wencheng Feng, Heng Yu, Haihui Zhao, Xiaolan Hou, Shumei Jia, Chengkui Li, Yulin Cheng, Paolo Tozzi, Ming Sun, Yong chen
We study the structural and dynamical properties of Abell 209 based on Chandra and XMM-Newton observations. We obtain detailed temperature, pressure and entropy maps with the contour binning method, and find a hot region in the NW direction. The X-ray brightness residual map and corresponding temperature profiles reveal a possible shock front in the NW direction and a cold front feature in the SE direction. Combing with the galaxy luminosity density map we propose a weak merger scenario. A young sub-cluster passing from the SE to NW direction could explain the optical subpeak, the ICM temperature map, the X-ray surface brightness excess, and the X-ray peak offset togethe.
{"title":"Weak Merging scenario of the CLASH Cluster A209","authors":"Wencheng Feng, Heng Yu, Haihui Zhao, Xiaolan Hou, Shumei Jia, Chengkui Li, Yulin Cheng, Paolo Tozzi, Ming Sun, Yong chen","doi":"10.1088/1674-4527/ad349a","DOIUrl":"https://doi.org/10.1088/1674-4527/ad349a","url":null,"abstract":"\u0000 We study the structural and dynamical properties of Abell 209 based on Chandra and XMM-Newton observations. We obtain detailed temperature, pressure and entropy maps with the contour binning method, and find a hot region in the NW direction. The X-ray brightness residual map and corresponding temperature profiles reveal a possible shock front in the NW direction and a cold front feature in the SE direction. Combing with the galaxy luminosity density map we propose a weak merger scenario. A young sub-cluster passing from the SE to NW direction could explain the optical subpeak, the ICM temperature map, the X-ray surface brightness excess, and the X-ray peak offset togethe.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"26 48","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140240158","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 : 2024-03-13DOI: 10.1088/1674-4527/ad339f
Zhenyu Wang, Ju-Jia Zhang, X. Er, Jinming Bai
The multi-channel photometric survey telescope (Mephisto) is a real-time, three-color photometric system designed to capture the color evolution of stars and transients accurately. This telescope system can be crucial in cosmological distance measurements of low-redshift (low-z, z $lesssim 0.1$) Type Ia supernovae (SNe Ia). To optimize the capabilities of this instrument, we performed a comprehensive simulation study before its official operation. By considering the impact of atmospheric extinction, weather conditions, and the lunar phase at the observing site involving the instrumental features, we simulated the light curve of SNe Ia obtained by the Mephisto. The best strategy in the case of SNe Ia cosmology is to take the image at an exposure time of 130 s with a cadence of 3 d. In this condition, Mephisto can obtain hundreds of high-quality SNe Ia to achieve a distance measurement better than $4.5%$. Given the on-time spectral classification and monitoring of the Lijiang 2.4m telescope at the same observatory, Mephisto, in the whole operation, can significantly enrich the well-calibrated sample of supernovae at low-z and improve the calibration accuracy of high-redshift (high-z) SNe Ia.
{"title":"Prospects of the multi-channel photometric survey telescope in the cosmological application of Type Ia supernovae","authors":"Zhenyu Wang, Ju-Jia Zhang, X. Er, Jinming Bai","doi":"10.1088/1674-4527/ad339f","DOIUrl":"https://doi.org/10.1088/1674-4527/ad339f","url":null,"abstract":"\u0000 The multi-channel photometric survey telescope (Mephisto) is a real-time, three-color photometric system designed to capture the color evolution of stars and transients accurately. This telescope system can be crucial in cosmological distance measurements of low-redshift (low-z, z $lesssim 0.1$) Type Ia supernovae (SNe Ia). To optimize the capabilities of this instrument, we performed a comprehensive simulation study before its official operation. By considering the impact of atmospheric extinction, weather conditions, and the lunar phase at the observing site involving the instrumental features, we simulated the light curve of SNe Ia obtained by the Mephisto. The best strategy in the case of SNe Ia cosmology is to take the image at an exposure time of 130 s with a cadence of 3 d. In this condition, Mephisto can obtain hundreds of high-quality SNe Ia to achieve a distance measurement better than $4.5%$. Given the on-time spectral classification and monitoring of the Lijiang 2.4m telescope at the same observatory, Mephisto, in the whole operation, can significantly enrich the well-calibrated sample of supernovae at low-z and improve the calibration accuracy of high-redshift (high-z) SNe Ia.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"2012 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140246367","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 : 2024-03-13DOI: 10.1088/1674-4527/ad339e
Hui Li, Rongwang Li, Peng Shu, Yuqiang Li
Attitude is one of the crucial parameters for space objects and plays a vital role in collision prediction and debris removal. Analyzing light curves to determine attitude is the most commonly used method. In photometric observations, outliers may exist in the obtained light curves due to various reasons. Therefore, preprocessing is required to remove these outliers to obtain high quality light curves. Through statistical analysis, the reasons leading to outliers can be categorized into two main types: first, the brightness of the object significantly increases due to the passage of a star nearby, referred to as "stellar contamination," and second, the brightness markedly decreases due to cloudy cover, referred to as "cloudy contamination." Traditional approach of manually inspecting images for contamination is time-consuming and labor-intensive. However, We propose the utilization of machine learning methods as a substitute. Convolutional Neural Networks (CNN) and Support Vector Machines (SVM) are employed to identify cases of stellar contamination and cloudy contamination, achieving accuracies of 100% and 97.12%, respectively. We also explored other machine learning methods such as Residual Network-18 (ResNet-18) and Light Gradient Boosting Machine (lightGBM), then conducted comparative analyses of the results.
{"title":"Machine Learning-Based Identification of Contaminated Images in Light Curves Data Preprocessing","authors":"Hui Li, Rongwang Li, Peng Shu, Yuqiang Li","doi":"10.1088/1674-4527/ad339e","DOIUrl":"https://doi.org/10.1088/1674-4527/ad339e","url":null,"abstract":"\u0000 Attitude is one of the crucial parameters for space objects and plays a vital role in collision prediction and debris removal. Analyzing light curves to determine attitude is the most commonly used method. In photometric observations, outliers may exist in the obtained light curves due to various reasons. Therefore, preprocessing is required to remove these outliers to obtain high quality light curves. Through statistical analysis, the reasons leading to outliers can be categorized into two main types: first, the brightness of the object significantly increases due to the passage of a star nearby, referred to as \"stellar contamination,\" and second, the brightness markedly decreases due to cloudy cover, referred to as \"cloudy contamination.\" Traditional approach of manually inspecting images for contamination is time-consuming and labor-intensive. However, We propose the utilization of machine learning methods as a substitute. Convolutional Neural Networks (CNN) and Support Vector Machines (SVM) are employed to identify cases of stellar contamination and cloudy contamination, achieving accuracies of 100% and 97.12%, respectively. We also explored other machine learning methods such as Residual Network-18 (ResNet-18) and Light Gradient Boosting Machine (lightGBM), then conducted comparative analyses of the results.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140246189","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}
From the mid-19th century to the end of the 20th century, photographic plates served as the primary detectors for astronomical observations. Astronomical photographic observations in China began in 1901, and over a century, a total of approximately 30,000 astronomical photographic plates have been captured. These historical plates play an irreplaceable role in conducting long-term, time-domain astronomical research. To preserve and explore these valuable original astronomical observational data, Shanghai Astronomical Observatory has organized the transportation of plates taken at night from various stations across the country to the Sheshan Plate Archive for centralized preservation. For the first time, plate information statistics was performed. On this basis, the plates were cleaned and digitally scanned, and finally digitized images were acquired for 29,314 plates. In this study, using Gaia DR2 as the reference star catalog, astrometric processing has been carried out successfully on 15,696 single-exposure plates, including object extraction, stellar identification, and plate model computation. As a result, for long focal length telescopes, such as the 40cm double-tube refractor telescope and the 1.56m reflector telescope at the Shanghai Astronomical Observatory and the 1m reflector telescope at the Yunnan Astronomical Observatory, the astrometric accuracy obtained for their plates is approximately 0.1′′ to 0.3′′. The distribution of astrometric accuracy for medium and short focal length telescopes ranges from 0.3′′ to 1.0′′. The relevant data of this batch of plates, including digitized images and stellar catalog of the plates are archived and released by the National Astronomical Data Center. Users can access and download plate data based on keywords such as station, telescope, observation year, and observed celestial coordinates.
{"title":"Digitization of Astronomical Photographic Plate of China and Astrometric Measurement of Single-exposure Plates","authors":"Z. Shang, Yong Yu, Liangliang Wang, Mei-Ting Yang, Jing Yang, Shiyin Shen, Min Liu, 权峰 徐, Chenzhou Cui, Dongwei Fan, Zhenghong Tang, Jian-hai Zhao","doi":"10.1088/1674-4527/ad339d","DOIUrl":"https://doi.org/10.1088/1674-4527/ad339d","url":null,"abstract":"\u0000 From the mid-19th century to the end of the 20th century, photographic plates served as the primary detectors for astronomical observations. Astronomical photographic observations in China began in 1901, and over a century, a total of approximately 30,000 astronomical photographic plates have been captured. These historical plates play an irreplaceable role in conducting long-term, time-domain astronomical research. To preserve and explore these valuable original astronomical observational data, Shanghai Astronomical Observatory has organized the transportation of plates taken at night from various stations across the country to the Sheshan Plate Archive for centralized preservation. For the first time, plate information statistics was performed. On this basis, the plates were cleaned and digitally scanned, and finally digitized images were acquired for 29,314 plates. In this study, using Gaia DR2 as the reference star catalog, astrometric processing has been carried out successfully on 15,696 single-exposure plates, including object extraction, stellar identification, and plate model computation. As a result, for long focal length telescopes, such as the 40cm double-tube refractor telescope and the 1.56m reflector telescope at the Shanghai Astronomical Observatory and the 1m reflector telescope at the Yunnan Astronomical Observatory, the astrometric accuracy obtained for their plates is approximately 0.1′′ to 0.3′′. The distribution of astrometric accuracy for medium and short focal length telescopes ranges from 0.3′′ to 1.0′′. The relevant data of this batch of plates, including digitized images and stellar catalog of the plates are archived and released by the National Astronomical Data Center. Users can access and download plate data based on keywords such as station, telescope, observation year, and observed celestial coordinates.","PeriodicalId":509923,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"311 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140247106","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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