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Molecular outflows and gas rotation associated with G20.08–0.14N

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Research in Astronomy and Astrophysics 2013年第11期13卷 1295-1306页

作者： nai-ping yu Jun-Jie Wang National Astronomical Observatories Chinese Academy of Sciences NAOC-TU Joint Center for Astrophysics

We present the results of a high-resolution study with the Submillimeter Array （SMA） toward the massive star-forming complex G20.08-0.14N. With the SMA data, we have detected and analyzed the transitions in the 12CO （3-2） and 12CO （2-1） molecular lines as well as CHaCN. The millimeter observations reveal highly collimated bipolar molecular outflows, traced by high-velocity 12CO （2-1） and 12CO （3-2） emissions. Using a rotation temperature diagram, we derive that the rota- tional temperature and the column density of CHaCN are 244 K and 1.2 ~ 1015 cm-2, respectively. We also suggest that the minor outflow is probably driven by the hy- percompact （HC） HII region A that is inside. We find the molecular gas （traced by ClrO, SO, CH3OH and SO2） surrounding G20.08-0.14N appears to be undergoing bulk rotation. The HCHII region A that is inside is most probably the main source of accretion and heating for G20.08-0.14N.

关键词： ISM: individual objects (G20.08-0.14N) -- ISM: molecules -- radiolines: ISM -- stars: formation-- ISM: kinematics and dynamics

A multi-transition molecular line study of infrared dark cloud G331.71+00.59

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Research in Astronomy and Astrophysics 2013年第1期13卷 28-38页

作者： nai-ping yu Jun-Jie Wang National Astronomical Observatories Chinese Academy of Sciences NAOC-TU Joint Center for Astrophysics

Using archive data from the Millimeter Astronomy Legacy Team Survey at 90 GHz （MALT90）, carried out using the Mopra 22-m telescope, we made the first multi-transition molecular line study of infrared dark cloud （IRDC） MSXDC G331.71＋00.59. Two molecular cores were found embedded in this IRDC. Each of these cores is associated with a known extended green object （EGO）, indicating places of massive star formation. The HCO＋（1-0） and HNC （1-0） transitions show promi- nent blue or red asymmetric structures, suggesting outflow and inflow activities of young stellar objects （YSOs）. Other detected molecular lines include H13CO＋（1- 0）, C2H （1-0）, HC3N （10-9）, HNCO（40,4-30,3） and SiO （2-1）, which are typical of hot cores and outflows. We regard the two EGOs as evolving from the IRDC to hot cores. Using public GLIMPS data, we investigate the spectral energy distribution of EGO G331.71＋0.60. Our results support this EGO being a massive YSO driving the outflow. G331.71＋0.58 may be at an earlier evolutionary stage.

关键词： stars: formation -- ISM: outflows -- ISM: molecules

HNCO： a molecule that traces low-velocity shocks

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Research in Astronomy and Astrophysics 2018年第2期18卷 19-36页

作者： nai-ping yu Jing-Long Xu Jun-Jie Wang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China NAOC-TU Joint Center for Astrophysics Lhasa 850000 China

Using data from Millimetre Astronomy Legacy Team Survey at 90 GHz （MALT90）, we present a molecular line study of a sample of APEX Telescope Large Area Survey of the Galaxy （ATLASGAL） clumps. Twelve emission lines have been detected in all. We found that in most sources, emissions of HC3N, HN13C, CH3CN, HNCO and SiO show more compact distributions than those of HCO＋, HNC, HCN and N2H＋. By comparing with other molecular lines, we found that the abun- dance of HNCO （x（HNCO）） correlates well with other species such as HC3N, HNC, C2H, H13CO＋ and N2H＋. Previous studies indicate the HNCO abundance could be enhanced by shocks. However, in this study, we find the abundance of HNCO does not correlate well with that of SiO, which is also a good tracer of shocks. We suggest this may be because HNCO and SiO trace different parts of shocks. Our analysis indicates that the velocity of a shock traced by HNCO tends to be lower than that traced by SiO. In the low-velocity shocks traced by HNCO, the HNCO abundance increases faster than that of SiO. While in the relatively high-velocity shocks traced by SiO, the SiO abundance increases faster than that of HNCO. We suggest that in the infrared dark cloud MSXDC G331.71＋00.59, high-velocity shocks are destroying the molecule HNCO.

关键词： stars: formation- ISM: abundances- ISM: clouds- ISM: molecules

Radio recombination line observations at 1.0-1.5 GHz with FAST

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Research in Astronomy and Astrophysics 2021年第8期21卷 269-274页

作者： Chuan-Peng Zhang Jin-Long Xu Guang-Xing Li Li-Gang Hou nai-ping yu Peng Jiang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China South-Western Institute for Astronomy Research Yunnan UniversityKunming 650500China

H Ⅱ regions made of gas ionized by radiations from young massive stars,are widely distributed in the Milky *** are tracers for star formation,and their distributions are correlated with the Galactic spiral *** recombination lines(RRLs) of hydrogen and other atoms allow for the most precise determination of physical parameters such as temperature and ***,RRLs at around 1.4 GHz from HⅡ regions are weak and their detections are *** a result,only a limited number of detections have been obtained *** 19-beam receiver on board of the Five-hundred-meter Aperture Spherical radio Telescope(FAST) can simultaneously cover 23 RRLs for Hnα,Henα,and Cnα(n=164-186),***,combined with its unparalleled collecting area,makes FAST the most powerful telescope to detect weak *** this pilot survey,we use FAST to observe nine HⅡ regions at L *** allocate20 minutes pointing time for each source to achieve a sensitivity of around 9 mK in a velocity resolution of2.0 km s^(-1).In total,21 RRLs for Hnα and Cnα at 1.0-1.5 GHz have been simultaneously detected with strong emission ***,the detection rates for the H167α and C167α RRLs are 100%,while that for the He167α RRL is 33.3%.Using hydrogen and helium RRLs,we measure the electron density,electron temperature,and pressure for three HⅡ *** pilot survey demonstrates the capability of FAST in RRL measurements,and a statistically meaningful sample with RRL detection,through which knowledge about Galactic spiral structure and evolution can be obtained,is expected in the future.

关键词： telescopes:FAST HⅡregions radio lines:ISM galaxies:star formation

HI detection of J030417.78+002827.4 by the Five-hundred-meter Aperture Spherical Radio Telescope

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Research in Astronomy and Astrophysics 2021年第4期21卷 282-286页

作者： nai-ping yu Lei Qian Chuan-Peng Zhang Peng Jiang Jin-Long Xu Jun-Jie Wang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China

We present the first HI 21 cm spectroscopy detection of J030417.78+002827.4,which is an active galactic nucleus(AGN)with an intermediate-mass black hole(IMBH)in the *** observations were carried out with the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)last *** relied on the ON-OFF observing approach with the 19-beam receiver covering 1.05-1.45 *** a total integration time of about 20 min,the root mean square(RMS)of our data reaches 1.2 mJy beam-1,at a velocity resolution of 1.6 km s^(-1).Radio frequency interference(RFI)is checked and excluded during the data *** detected HI spectroscopy shows a dual-horned profile with a line width of 223.5 km s^(-1),indicating gas rotation around this *** redshift of this galaxy derived from our HI observation *** calculate the atomic gas mass by the integrated flux of the HI emission *** total gas mass in this galaxy is estimated to be 1.8×10^(10)M☉.We find the fraction of gas-to-stellar mass ratio in J030417.78+002827.4 is more than 50%.This ratio is much higher than the typical value found in other AGNs with supermassive black holes(SMBHs),and is comparable to some star-forming galaxies recently observed by FAST.

关键词： galaxies:ISM radio line:profiles

Searching for initial stage of massive star formation around the HⅡ region G18.2–0.3

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Research in Astronomy and Astrophysics 2017年第6期17卷 77-88页

作者： Chuan-Peng Zhang Jing-Hua yuan Jin-Long Xu Xiao-Lan Liu nai-ping yu Nan Li Li-ping He Guo-Yin Zhang Jun-Jie Wang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

Sometimes, early star formation can be found in cold and dense molecular clouds, such as an infrared dark cloud. Considering that star formation often occurs in clusters, H II regions may be triggering a new generation of star formation, so we can search for the initial stage of massive star formation around H II regions. Based on the above, this work introduces one method to search for the initial stage of massive star formation around H II regions. Towards one section of the H II region G18.2-0.3, multiwavelength observations are carried out to investigate its physical properties. Through analysis, we find three potential initial stages of massive star formation, suggesting that it is feasible to use in searching for the initial stage of massive star formation around H II regions.

关键词： infrared stars - stars formation - initial stage - H II regions

The FAST all sky HI survey(FASHI):The first release of catalog

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 112-133页

作者： Chuan-Peng Zhang Ming Zhu Peng Jiang Cheng Cheng Jing Wang Jie Wang Jin-Long Xu Xiao-Lan Liu nai-ping yu Lei Qian Haiyang yu Mei Ai Yingjie Jing Chen Xu Ziming Liu Xin Guan Chun Sun Qingliang Yang Menglin Huang Qiaoli Hao FAST Collaboration Guizhou Radio Astronomical Observatory Guizhou UniversityGuiyang 550000China National Astronomical Observatories Chinese Academy of Sciences(CAS)Beijing 100101China Chinese Academy of Sciences South America Center for Astronomy National Astronomical ObservatoriesCASBeijing 100101China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

The FAST All Sky HI survey(FASHI)was designed to cover the entire sky observable by the Five-hundred-meter Aperture Spherical radio Telescope(FAST),spanning approximately 22000 square degrees of declination between-14°and+66°,and in the frequency range of 1050-1450 MHz,with the expectation of eventually detecting more than 100000 HI *** August 2020 and June 2023,FASHI had covered more than 7600 square degrees,which is approximately 35%of the total sky observable by *** has a median detection sensitivity of around 0.76 m Jy beam-1and a spectral line velocity resolution of~6.4 km s-1at a frequency of~1.4 *** of now,a total of 41741 extragalactic HI sources have been detected in the frequency range 1305.5-1419.5 MHz,corresponding to a redshift limit of z■*** cross-matching FASHI sources with the Siena Galaxy Atlas(SGA)and the Sloan Digital Sky Survey(SDSS)catalogs,we found that 16972(40.7%)sources have spectroscopic redshifts and 10975(26.3%)sources have only photometric *** of the remaining 13794(33.0%)HI sources are located in the direction of the Galactic plane,making their optical counterparts difficult to identify due to high extinction or high contamination of Galactic stellar *** on current survey results,the FASHI survey is an unprecedented blind extragalactic H I *** has higher spectral and spatial resolution and broader coverage than the Arecibo Legacy Fast ALFA Survey(ALFALFA).When completed,FASHI will provide the largest extragalactic HI catalog and an objective view of HI content and large-scale structure in the local universe.

关键词： surveys redshifts galaxies telescope radio lines HI line

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New HⅠObservations Toward the NGC 5055 Galaxy Group with FAST

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Research in Astronomy and Astrophysics 2024年第7期24卷 249-256页

作者： Xiao-Lan Liu Ming Zhu Jin-Long Xu Peng Jiang Chuan-Peng Zhang nai-ping yu Jun-Jie Wang Yan-Bin Yang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Guizhou Radio Astronomical Observatory Guizhou UniversityGuiyang 550000China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China GEPI Observatoire de ParisUniversite PSLCNRSPlace Jules Janssen92195 MeudonFrance

We report a new high-sensitivity HⅠmapping observation of the NGC 5055 galaxy group over an area of 1°.5×0°.75 with the Five-hundred-meter Aperture Spherical radio Telescope(FAST).Our observation reveals that the warped HⅠdisk of NGC 5055 is more extended than what was previously observed by WSRT,out to239(61.7 kpc).The total HⅠmass of NGC 5055 is determined to be~1.1×10^(10)M_Θ.We identified three HⅠclouds with HⅠmasses of the order of~10^(7)M_Θat the southeastern edge of the HⅠdisk,as well as a candidate high-velocity cloud with an HⅠmass of(1.2±0.5)×10^(6)M_Θto the north of NGC *** HⅠcontent of UGCA337 is robustly detected for the first time by the FAST *** has a narrow HⅠlinewidth of W_(50)=17.4±3.8 km s^(-1)with a total HⅠmass of(3.5±0.3)×10^(6)M_Θ.Comparing the gas content and g-r color of UGCA 337 with typical low-mass dwarf galaxies,UGCA 337 appears relatively gas-poor despite its blue *** suggests that UGCA 337 may have undergone gas stripping in the *** also analyzed the possible origin of the diffuse HⅠclouds located at the outskirts of NGC 5055,and speculate that they might be the remnant features of a merger event in the past.

关键词： galaxies evolution-galaxies structure-galaxies individual(NGC 5055)-galaxies kinematics and dynamics-galaxies interactions

Probing star formation and feedback using CCOSMA and archival data in the CFG028.68–0.28 quasi-sinusoidal filament

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Research in Astronomy and Astrophysics 2019年第12期19卷 305-317页

作者： Jin-Long Xu Jirgen Stutzki yuefang Wu Xin Guan Jun-Jie Wang M.Miller Yang Chen Sheng-Li Qin Jun-Zhi Wang Chang-Chun Ning Danzengluobu Tian-Lu Chen nai-ping yu Chuan-Peng Zhang Xiao-Lan Liu Jian-Bin L Karl Jacobs Urs UGraf Gang Xu Nan Li Guo-Yin Zhang and Qi Wu National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China I.Physikalisches Institut Universitat zu KolnZilpicher Str.7750937 KolnGermany Department of Astronomy Peking UniversityBeijing 100871China School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Department of Astronomy Yunnan Universityand Key Laboratory of Astroparticle Physics of Yunnan ProvinceKunming 650091China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Tibet University LhasaTibet 850000China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China NAOC-TU Joint Center for Astrophysics Lhasa 850000China

We have performed a multi-wavelength study toward a quasi-sinusoidal filament(CFG028.68–0.28). A new large-scale ^12CO J = 3-2 map was obtained from the China-Cologne Observation for Sub Millimeter Astronomy(CCOSMA) 3m radio telescope. Based on the ATLASGAL catalog, we have identified 27 dust clumps in the filament. Through the relationship between the mass and radius of these clumps, 67% of these clumps are dense and massive enough to potentially form massive stars. The obtained CFE is ~11% in the filament. The filament has a linear mass density of ~305 M⊙pc^-1, which is smaller than its critical mass to length ratio. This suggests that the external pressure from the neighboring H Ⅱ regions may help prevent the filament from dispersing under the effects of turbulence. Comparing the energy injection from outflows and H Ⅱ regions in the filament, the ionization feedback from the H Ⅱ regions can help maintain the observed turbulence.

关键词： stars:formation stars:early-type ISM:HⅡregions ISM:individual(CFG028.68-0.28,IRDC G28.53-0.25,and N49)