利用赫歇尔空间望远镜的H-ATLAS(Herschel Astrophysical Terahertz Large Area Survey)SDP(Science Demonstration Phase)天区从紫外到亚毫米波段数据,结合星族合成方法和尘埃模型,计算了星系的红外总光度.在此基础上,分别针对强恒星...利用赫歇尔空间望远镜的H-ATLAS(Herschel Astrophysical Terahertz Large Area Survey)SDP(Science Demonstration Phase)天区从紫外到亚毫米波段数据,结合星族合成方法和尘埃模型,计算了星系的红外总光度.在此基础上,分别针对强恒星形成星系和弱恒星形成星系,研究了利用紫外光度、红外光度和Hα谱线计算得到的恒星形成率(Star Formation Rate,SFR)的差异以及导致差异的内在物理起因.发现对于恒星形成活动强的星系,这3种恒星形成率指针给出的结果基本一致,弥散较小、只是在高恒星形成率端,利用紫外光度算得的恒星形成率比利用Hα谱线流量算得的恒星形成率略微偏小;而在低恒星形成率端,紫外光度指针偏大于Hα谱线指针;红外光度指针与Hα谱线指针在两端无明显偏差.对弱恒星形成星系,紫外光度、Hα谱线和红外光度3种恒星形成率指针存在明显的差异,且弥散较大.利用紫外光度和Hα谱线计算得到的恒星形成率的弥散和系统偏差随着星系年龄、质量的增加而增大.系统偏差增大的主要原因是利用紫外连续谱斜率β定标恒星形成活动较弱星系的消光时,高估了这些星系的紫外消光,使得消光改正后的紫外光度偏大.另外,MPA/JHU(Max Planck Institute for Astrophysics/Johns Hopkins University)数据库中弱恒星形成星系的恒星形成率SFR(Hα)比真实值偏低.展开更多
Molecular line emissions are commonly used to trace the distribution and properties of molecular Interstella Medium.However,the emissions are heavily blended on the Galactic disk toward the inner Galaxy because of th ...Molecular line emissions are commonly used to trace the distribution and properties of molecular Interstella Medium.However,the emissions are heavily blended on the Galactic disk toward the inner Galaxy because of th relatively large line widths and the velocity overlaps of spiral arms.Structure identification methods based on voxe connectivity in Position-Position-Velocity(PPV)data cubes often produce unrealistically large structures,which i the“over-linking”problem.Therefore,identifying molecular cloud structures in these directions is not trivial.W propose a new method based on Gaussian decomposition and graph theory to solve the over-linking problem named InterStellar Medium Gaussian Component Clustering(ISMGCC).Using the Milky Way Imaging Scrol Painting(MWISP)^(13)CO(1-0)data in the range of 13°.5≤l≤14°.5,|b|≤0°.5,and-100≤V_(lsr)≤+200 km s^(-1),our method identified three hundred molecular gas structures with at least 16 pixels.These structures contain 92%of the total flux in the raw data cube and show single-peaked line profiles on more than 93%of their pixels.Th ISMGCC method could distinguish gas structures in crowded regions and retain most of the flux without globa data clipping or assumptions on the structure geometry,meanwhile,allowing multiple Gaussian components fo complicated line profiles.展开更多
Molecules reside broadly in the interstellar space and can be detected via spectroscopic observations.To date,more than 271 molecular species have been identified in interstellar medium or circumstellar envelopes.Mole...Molecules reside broadly in the interstellar space and can be detected via spectroscopic observations.To date,more than 271 molecular species have been identified in interstellar medium or circumstellar envelopes.Molecular spectroscopic parameters measured in laboratory make the identification of new species and derivation of physical parameters possible.These spectroscopic parameters are systematically collected into databases,two of the most commonly used being the CDMS and JPL databases.While new spectroscopic parameters are continuously measured/calculated and added to those databases,at any point in time it is the existing spectroscopic data that ultimately limits what molecules can possibly be identified in astronomical data.In this work,we conduct a meta-analysis of the CDMS and JPL databases.We show the statistics of transition frequencies and their uncertainties in these two databases,and discuss the line confusion problem under certain physical environments.We then assess the prospects of detecting molecules in common ISM environments using a few facilities that are expected to be conducting spectroscopic observations in the future.Results show that CSST/HSTDM and SKA1-mid have the potential to detect some complex organic molecules,or even amino acids,with reasonable assumptions about ISM environments.展开更多
针对微纳卫星的测控数传需求,利用业务无线电及ISM(Industrial-Scientific-Medical,工业-科学-医疗)频段和设备,设计了适用微纳卫星的便携式测控站,包括ISM和VHF/UHF(Very High Frequency/Ultra High Frequency,甚高频/超高频)2个通道;...针对微纳卫星的测控数传需求,利用业务无线电及ISM(Industrial-Scientific-Medical,工业-科学-医疗)频段和设备,设计了适用微纳卫星的便携式测控站,包括ISM和VHF/UHF(Very High Frequency/Ultra High Frequency,甚高频/超高频)2个通道;优选了COTS(Commercial Off The Shelf,商用现货)ISM通信电台和VHF/UHF全模式电台、VHF/UHF八木天线、S频段花瓣式网状抛物面天线等部组件,3副天线共用1个伺服机构;并对ISM和VHF/UHF信道的上/下行链路电平进行估算。结果表明:该多频段多通道便携测控站的设计方案可行性好,效费比高,并已在相关微纳卫星的测控应用中得到验证。展开更多
文摘利用赫歇尔空间望远镜的H-ATLAS(Herschel Astrophysical Terahertz Large Area Survey)SDP(Science Demonstration Phase)天区从紫外到亚毫米波段数据,结合星族合成方法和尘埃模型,计算了星系的红外总光度.在此基础上,分别针对强恒星形成星系和弱恒星形成星系,研究了利用紫外光度、红外光度和Hα谱线计算得到的恒星形成率(Star Formation Rate,SFR)的差异以及导致差异的内在物理起因.发现对于恒星形成活动强的星系,这3种恒星形成率指针给出的结果基本一致,弥散较小、只是在高恒星形成率端,利用紫外光度算得的恒星形成率比利用Hα谱线流量算得的恒星形成率略微偏小;而在低恒星形成率端,紫外光度指针偏大于Hα谱线指针;红外光度指针与Hα谱线指针在两端无明显偏差.对弱恒星形成星系,紫外光度、Hα谱线和红外光度3种恒星形成率指针存在明显的差异,且弥散较大.利用紫外光度和Hα谱线计算得到的恒星形成率的弥散和系统偏差随着星系年龄、质量的增加而增大.系统偏差增大的主要原因是利用紫外连续谱斜率β定标恒星形成活动较弱星系的消光时,高估了这些星系的紫外消光,使得消光改正后的紫外光度偏大.另外,MPA/JHU(Max Planck Institute for Astrophysics/Johns Hopkins University)数据库中弱恒星形成星系的恒星形成率SFR(Hα)比真实值偏低.
基金sponsored by the National Key R&D Program of China under grants 2023YFA1608000,2017YFA0402701the CAS Key Research Program of Frontier Sciences under grant QYZDJ-SSW-SLH047+1 种基金supported by the National Natural Science Foundation of China(NSFC,grant Nos.U2031202,12373030,and 11873093)the Natural Science Foundation of Jiangsu Province(grant No.BK20231509)。
文摘Molecular line emissions are commonly used to trace the distribution and properties of molecular Interstella Medium.However,the emissions are heavily blended on the Galactic disk toward the inner Galaxy because of th relatively large line widths and the velocity overlaps of spiral arms.Structure identification methods based on voxe connectivity in Position-Position-Velocity(PPV)data cubes often produce unrealistically large structures,which i the“over-linking”problem.Therefore,identifying molecular cloud structures in these directions is not trivial.W propose a new method based on Gaussian decomposition and graph theory to solve the over-linking problem named InterStellar Medium Gaussian Component Clustering(ISMGCC).Using the Milky Way Imaging Scrol Painting(MWISP)^(13)CO(1-0)data in the range of 13°.5≤l≤14°.5,|b|≤0°.5,and-100≤V_(lsr)≤+200 km s^(-1),our method identified three hundred molecular gas structures with at least 16 pixels.These structures contain 92%of the total flux in the raw data cube and show single-peaked line profiles on more than 93%of their pixels.Th ISMGCC method could distinguish gas structures in crowded regions and retain most of the flux without globa data clipping or assumptions on the structure geometry,meanwhile,allowing multiple Gaussian components fo complicated line profiles.
基金financially supported by the National Natural Science Foundation of China through grants 12041305 and 11873094by the China Manned Space Project。
文摘Molecules reside broadly in the interstellar space and can be detected via spectroscopic observations.To date,more than 271 molecular species have been identified in interstellar medium or circumstellar envelopes.Molecular spectroscopic parameters measured in laboratory make the identification of new species and derivation of physical parameters possible.These spectroscopic parameters are systematically collected into databases,two of the most commonly used being the CDMS and JPL databases.While new spectroscopic parameters are continuously measured/calculated and added to those databases,at any point in time it is the existing spectroscopic data that ultimately limits what molecules can possibly be identified in astronomical data.In this work,we conduct a meta-analysis of the CDMS and JPL databases.We show the statistics of transition frequencies and their uncertainties in these two databases,and discuss the line confusion problem under certain physical environments.We then assess the prospects of detecting molecules in common ISM environments using a few facilities that are expected to be conducting spectroscopic observations in the future.Results show that CSST/HSTDM and SKA1-mid have the potential to detect some complex organic molecules,or even amino acids,with reasonable assumptions about ISM environments.
文摘针对微纳卫星的测控数传需求,利用业务无线电及ISM(Industrial-Scientific-Medical,工业-科学-医疗)频段和设备,设计了适用微纳卫星的便携式测控站,包括ISM和VHF/UHF(Very High Frequency/Ultra High Frequency,甚高频/超高频)2个通道;优选了COTS(Commercial Off The Shelf,商用现货)ISM通信电台和VHF/UHF全模式电台、VHF/UHF八木天线、S频段花瓣式网状抛物面天线等部组件,3副天线共用1个伺服机构;并对ISM和VHF/UHF信道的上/下行链路电平进行估算。结果表明:该多频段多通道便携测控站的设计方案可行性好,效费比高,并已在相关微纳卫星的测控应用中得到验证。
