This paper presents an overview of the QUARKS survey,which stands for Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures."The QUARKS survey is observing139 m...This paper presents an overview of the QUARKS survey,which stands for Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures."The QUARKS survey is observing139 massive clumps covered by 156 pointings at Atacama Large Millimeter/submillimeter Array(ALMA)Band 6(λ~1.3 mm).In conjunction with data obtained from the ALMA-ATOMS survey at Band 3(λ~3 mm),QUARKS aims to carry out an unbiased statistical investigation of massive star formation process within protoclusters down to a scale of 1000 au.This overview paper describes the observations and data reduction of the QUARKS survey,and gives a first look at an exemplar source,the mini-starburst Sgr B2(M).The wide-b and width(7.5 GHz)and high-angular-resolution(~0."3)observations of the QUARKS survey allow for the resolution of much more compact cores than those could be done by the ATOMS survey,and to detect previously unrevealed fainter filamentary structures.The spectral windows cover transitions of species including CO,SO,N_(2)D^(+),SiO,H_(30)α,H_(2)CO,CH_(3)CN,and many other complex organic molecules,tracing gas components with different temperatures and spatial extents.QUARKS aims to deepen our understanding of several scientific topics of massive star formation,such as the mass transport within protoclusters by(hub-)filamentary structures,the existence of massive starless cores,the physical and chemical properties of dense cores within protoclusters,and the feedback from already formed high-mass young protostars.展开更多
The next generation of very long baseline interferometry(VLBI)is stepping into the era of microarcsecond(μas)astronomy,and pushing astronomy,especially astrometry,to new heights.VLBI with the Square Kilometre Array(S...The next generation of very long baseline interferometry(VLBI)is stepping into the era of microarcsecond(μas)astronomy,and pushing astronomy,especially astrometry,to new heights.VLBI with the Square Kilometre Array(SKA),SKA-VLBI,will increase current sensitivity by an order of magnitude,and reach astrometric precision routinely below 10μas,even challenging 1μas.This advancement allows precise parallax and proper motion measurements of various celestial objects.Such improvements can be used to study objects(including isolated objects,and binary or multiple systems)in different stellar stages(such as star formation,main-sequence stars,asymptotic giant branch stars,pulsars,black holes,white dwarfs,etc.),unveil the structure and evolution of complex systems(such as the Milky Way),benchmark the international celestial reference frame,and reveal cosmic expansion.Furthermore,the theory of general relativity can also be tested with SKA-VLBI using precise measurements of light deflection under the gravitational fields of different solar system objects and the perihelion precession of solar system objects.展开更多
We present large-scale(2°×2°)observations toward the molecular cloud M120.1+3.0,using ^(12)CO,^(13)CO and C^(18)O(J=1-0)data from the Purple Mountain Observatory 13.7 m millimeter telescope.The distance...We present large-scale(2°×2°)observations toward the molecular cloud M120.1+3.0,using ^(12)CO,^(13)CO and C^(18)O(J=1-0)data from the Purple Mountain Observatory 13.7 m millimeter telescope.The distance of the cloud is measured to be~1.1 kpc.Using the ^(13)CO data,we identify a main filament F1 and two sub-filaments F2 and F3 in the cloud,which together show a"hub-filament"structure.Filaments F1 and F2 are thermally supercritical.Furthermore,F1 displays clear localized systematic motions in the ^(13)CO position-velocity diagram,which could be explained by accretion along the filament.The mean estimated accretion rate is~132M_(⊙)Myr^(-1).Approximately 150 ^(13)CO clumps are identified in the cloud,of which 39 are gravitationally bound.Most of these virialized clumps are well distributed along the supercritical filaments F1 and F2.Based on the complementary infrared and optical data,we identify~186 young stellar objects in the observed area and extract five clusters within the dense ridge of F1.The calculated star formation rate(SFR)surface densities(∑_(SFR))in the clusters range from 1.4 to 2.5 M_(⊙)Myr^(-1)pc^(-2),with a mean value of~2.0M_(⊙)Myr^(-1)pc^(-2).We therefore regard them as mini-starburst cluster candidates.The comparison between ∑_(SFR) and column density N_(gas) along the skeleton of F1 suggests that star formation is closely related to the dense gas in the cloud.Along the main filament F1,five bipolar outflows are also found.All these results indicate intense star-forming activities in the M120.1+3.0 molecular cloud.展开更多
Motivated by recent studies of the perturbation of the Magellanic Clouds(MCs)on the Milky Way(MW)and the planned multi-band wide-field deep survey named Chinese Space Station Telescope(CSST),we explore the detection l...Motivated by recent studies of the perturbation of the Magellanic Clouds(MCs)on the Milky Way(MW)and the planned multi-band wide-field deep survey named Chinese Space Station Telescope(CSST),we explore the detection limit of the MW reflex motion due to the MCs infall in different observation precision using an MW-MCs-mass galaxy from MAGPIE simulation to provide a reference for the CSST survey.By involving different errors of distance,proper motion,and radial velocity,we investigate the reflex motion characterized by the velocity shift in each velocity component.We find the strongest shifts in the tangential velocities,which align with the motion direction of the MCs.In the ideal case that distance errors dominate,we find a relative distance error of 10%can allow the reliable detection of velocity shifts in tangential velocities within 100 kpc,and a relative distance error of 30%is the minimum requirement to detect the reliable tangential velocity shifts of about 40kms^(-1)within 50 kpc.Different errors of proper motions in combination with a relative distance error of 10%or 20%show an error of 0.1 mas yr^(-1)in proper motions can guarantee the reliable detection of velocity shifts in V_(l)and V_(b)up to 80-100 kpc and an error of 0.15 mas yr^(-1)is the minimum requirement.In the other ideal case that radial velocity errors dominate,we find a radial velocity error of 20kms^(-1)can present reliable reflex motion in line-of-sight velocity up to 70 kpc,while the detection volume will be reduced to 50 kpc as the radial velocity error increases to 40kms^(-1).When the radial velocity error is larger than 60kms^(-1),the velocity shifts cannot be detected anymore.In addition,we find that reliable detection of reflex motion requires at least 20%of the whole sample.展开更多
基金supported by the National Key R&D Program of China(No.2022YFA1603100)the National Natural Science Foundation of China(NSFC)through grants Nos.12203086,12033005,12073061,12122307,and 12103045+12 种基金supported by CPSF No.2022M723278the international partnership program of Chinese Academy of Sciences through grant No.114231K YSB20200009Shanghai Pujiang Program 20PJ1415500the science research grants from the China Manned Space Project with no.CMS-CSST-2021-B06Yunnan Fundamental Research Project(grant No.202301AT070118)sponsored by Natural Science Foundation of Shanghai(No.23ZR1482100)support from the National Natural Science Foundation of China(NSFC)through grants Nos.12273090&12322305the Chinese Academy of Sciences(CAS)‘Light of West China’Program(No.xbzgzdsys-202212)support from the ANID BASAL project FB210003support from the Fondecyt Regular(project code 1220610)partially supported by a Grant-in-Aid for Scientific Research(KAKENHI Number JP22H01271 and JP23H01221)of JSPSsupported by JSPS KAKENHI(grant No.JP20H05645)sponsored(in part)by the Chinese Academy of Sciences(CAS),through a grant to the CAS South America Center for Astronomy(CASSACA)in Santiago,Chile。
文摘This paper presents an overview of the QUARKS survey,which stands for Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures."The QUARKS survey is observing139 massive clumps covered by 156 pointings at Atacama Large Millimeter/submillimeter Array(ALMA)Band 6(λ~1.3 mm).In conjunction with data obtained from the ALMA-ATOMS survey at Band 3(λ~3 mm),QUARKS aims to carry out an unbiased statistical investigation of massive star formation process within protoclusters down to a scale of 1000 au.This overview paper describes the observations and data reduction of the QUARKS survey,and gives a first look at an exemplar source,the mini-starburst Sgr B2(M).The wide-b and width(7.5 GHz)and high-angular-resolution(~0."3)observations of the QUARKS survey allow for the resolution of much more compact cores than those could be done by the ATOMS survey,and to detect previously unrevealed fainter filamentary structures.The spectral windows cover transitions of species including CO,SO,N_(2)D^(+),SiO,H_(30)α,H_(2)CO,CH_(3)CN,and many other complex organic molecules,tracing gas components with different temperatures and spatial extents.QUARKS aims to deepen our understanding of several scientific topics of massive star formation,such as the mass transport within protoclusters by(hub-)filamentary structures,the existence of massive starless cores,the physical and chemical properties of dense cores within protoclusters,and the feedback from already formed high-mass young protostars.
基金funded by the National Natural Science Foundation of China(NSFC,Grant Nos.12203104 and 11933011)the Natural Science Foundation of Jiangsu Province(grants No.BK20210999)+2 种基金the National SKA Program of China(grant No.2022SKA0120103)the Entrepreneurship and Innovation Program of Jiangsu Provincethe Key Laboratory for Radio Astronomy,CAS。
文摘The next generation of very long baseline interferometry(VLBI)is stepping into the era of microarcsecond(μas)astronomy,and pushing astronomy,especially astrometry,to new heights.VLBI with the Square Kilometre Array(SKA),SKA-VLBI,will increase current sensitivity by an order of magnitude,and reach astrometric precision routinely below 10μas,even challenging 1μas.This advancement allows precise parallax and proper motion measurements of various celestial objects.Such improvements can be used to study objects(including isolated objects,and binary or multiple systems)in different stellar stages(such as star formation,main-sequence stars,asymptotic giant branch stars,pulsars,black holes,white dwarfs,etc.),unveil the structure and evolution of complex systems(such as the Milky Way),benchmark the international celestial reference frame,and reveal cosmic expansion.Furthermore,the theory of general relativity can also be tested with SKA-VLBI using precise measurements of light deflection under the gravitational fields of different solar system objects and the perihelion precession of solar system objects.
基金supported by the National Key R&D Program of China(grant No.2017YFA0402702)the National Natural Science Foundation of China(NSFC,Grant Nos.12041305,12173090 and 12073079)+2 种基金the CAS International Cooperation Program(grant No.114332KYSB20190009)sponsored by the National Key R&D Program of China with grant 2017YFA0402701the CAS Key Research Program of Frontier Sciences with grant QYZDJ-SSW-SLH047。
文摘We present large-scale(2°×2°)observations toward the molecular cloud M120.1+3.0,using ^(12)CO,^(13)CO and C^(18)O(J=1-0)data from the Purple Mountain Observatory 13.7 m millimeter telescope.The distance of the cloud is measured to be~1.1 kpc.Using the ^(13)CO data,we identify a main filament F1 and two sub-filaments F2 and F3 in the cloud,which together show a"hub-filament"structure.Filaments F1 and F2 are thermally supercritical.Furthermore,F1 displays clear localized systematic motions in the ^(13)CO position-velocity diagram,which could be explained by accretion along the filament.The mean estimated accretion rate is~132M_(⊙)Myr^(-1).Approximately 150 ^(13)CO clumps are identified in the cloud,of which 39 are gravitationally bound.Most of these virialized clumps are well distributed along the supercritical filaments F1 and F2.Based on the complementary infrared and optical data,we identify~186 young stellar objects in the observed area and extract five clusters within the dense ridge of F1.The calculated star formation rate(SFR)surface densities(∑_(SFR))in the clusters range from 1.4 to 2.5 M_(⊙)Myr^(-1)pc^(-2),with a mean value of~2.0M_(⊙)Myr^(-1)pc^(-2).We therefore regard them as mini-starburst cluster candidates.The comparison between ∑_(SFR) and column density N_(gas) along the skeleton of F1 suggests that star formation is closely related to the dense gas in the cloud.Along the main filament F1,five bipolar outflows are also found.All these results indicate intense star-forming activities in the M120.1+3.0 molecular cloud.
基金supported by the National Key Research and Development Program of China No.2019YFA0405504the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-B03+4 种基金the National Natural Science Foundation of China(NSFC)grant Nos.11988101,11890694,12103062,12273027,12273053 and 12173046CAS Project for Young Scientists in Basic Research grant No.YSBR-062support from the K.C.Wong Foundationthe Sichuan Youth Science and Technology Innovation Research Team(grant No.21CXTD0038)the Innovation Team Funds of China West Normal University(grant No.KCXTD2022-6)。
文摘Motivated by recent studies of the perturbation of the Magellanic Clouds(MCs)on the Milky Way(MW)and the planned multi-band wide-field deep survey named Chinese Space Station Telescope(CSST),we explore the detection limit of the MW reflex motion due to the MCs infall in different observation precision using an MW-MCs-mass galaxy from MAGPIE simulation to provide a reference for the CSST survey.By involving different errors of distance,proper motion,and radial velocity,we investigate the reflex motion characterized by the velocity shift in each velocity component.We find the strongest shifts in the tangential velocities,which align with the motion direction of the MCs.In the ideal case that distance errors dominate,we find a relative distance error of 10%can allow the reliable detection of velocity shifts in tangential velocities within 100 kpc,and a relative distance error of 30%is the minimum requirement to detect the reliable tangential velocity shifts of about 40kms^(-1)within 50 kpc.Different errors of proper motions in combination with a relative distance error of 10%or 20%show an error of 0.1 mas yr^(-1)in proper motions can guarantee the reliable detection of velocity shifts in V_(l)and V_(b)up to 80-100 kpc and an error of 0.15 mas yr^(-1)is the minimum requirement.In the other ideal case that radial velocity errors dominate,we find a radial velocity error of 20kms^(-1)can present reliable reflex motion in line-of-sight velocity up to 70 kpc,while the detection volume will be reduced to 50 kpc as the radial velocity error increases to 40kms^(-1).When the radial velocity error is larger than 60kms^(-1),the velocity shifts cannot be detected anymore.In addition,we find that reliable detection of reflex motion requires at least 20%of the whole sample.
