About Me

Welcome to my personal webpage

I am an astronomer, and currently a postdoctoral researcher at the Max-Planck-Institute for Radio Astronomy (MPIfR), mainly focus on the multi-band (from radio to NIR) continuum and lines study toward ISM related to star formation in our Galaxy, using interferometer and single-dish telescopes.

Education & Background:

  • Since 2018 PostDoc at the Max-Planck-Institute for Radio Astronomy (MPIfR)
  • 2016-2017 SKA Joint Ph.D. University of Hertfordshire, UK
  • 2014-2018 Ph.D. National Astronomical Observatories of China (NAOC)

    • Main focus:

  • The birth of HII regions: HCHII and UCHII regions
  • Line study to investigate the outflow properties of the massive star formation
  • Multi-band continuum (from radio to NIR) study of ISM related to star formation
  • Observations of radio interferometer and single-dish telescopes
  • Multi-band (from radio to submm) RRLs study
  • Young PNe: kinematic distances and masers

    • Language and Skills:

  • Computer Language: python, C, R, and HTML
  • Language: English (fluent); Deutsch(beginner); Chinese(first language)
  • software: CASA, Obit, KVIS, TOPCAT, DS9, and GILDAS

    • Honors and Awards:

  • CAS Presidential Scholarship, "中科院院长奖" (2018)
  • China Scholarship Council Scholarship, SKA project, China-UK, "国家留学基金委奖学金" (2016)
  • National Scholarship of China, "国家奖学金" (2016)
  • Advanced Micro Devices (AMD) Scholarship at NAOC (2015), "AMD 奖学金"
  • Merit Student at NAOC, “中科院三好学生” (2015)
  • Volunteer of the CAS Public Science Day, “中科院公众科学日志愿者” (2013)
  • Valuable volunteer of IAU XXIII General Assembly, “第28届国际天文学联合大会(IAU)志愿者” (2012)
  • Enrolled in CAS without entrance examination, "推荐免试中科院研究生" (2011)
  • Outstanding student leader of College of Physics Science and Technology at XJU (2009)
  • Government grants for outstanding students (2007-2011)

    • Presentations:

  • Workshop talk, The SEDIGISM workshop, Bonn, Germany, Sep. 2021, Molecular outflows in the SEDIGISM survey
  • Talk at the MPIfR, Bonn, Germany, March. 2020, Hypercompact HII regions identified from young HII regions
  • Talk at the MPIfR, Bonn, Germany, Nov. 2018, Multi-band study of ISM related to massive star formation
  • Seminar talk, Chinese radio astronomy annual conference, Hefei, Anhui, China, Nov. 2017, Searching for hyper-compact HII regions using JVLA survey data
  • Seminar talk, the 2th Chinese annual conference of SKA, Shanghai, China, Dec., 2017, A search for steep positive radio spectrum object: make prediction for SKA and its precursors

    • Contact:

  • Email: ayyang@mpifr-bonn.mpg.de
  • Address: Auf dem Hügel 69, 53121, Bonn, Germany

    • Research

    Project I: Molecular outflows
    The formation processes of massive stars are unclear. Molecular outflows are common in the massive star formation, which is a usefull tool to understand the formation process of high-mass star. Outflows can be identified as CO lines showing high-velocity wings, with two spatially separated lobes that are respectively blue and red velocity shifted.

  • We undertake the largest outflow search toward clumps in the ATLASGAL survey using the 13CO and C18O spectra from the Galactic plane surveys of CHIMPS and SEDIGISM. We obtained the largest outflow sample so far, ~1500, and systematically discuss when outflow switches on, how it evolves, and what the impact on the matal clumps, with full details in Yang et al. 2018 and Yang et al. 2021b.

    • Massive Outflow Clumps, the birth places of massive stars
    The outflow wings identification processes are shown in slides (1) and (2), and the outflow lobes are mapped as presented in slide (3) and (4). Slide (5) displays the total sky region of outflow search as well as the ATLASGAL clumps (black dots and yellow circles) in the area. We discussed the correlations between outflow properties and clumps properties in slides (6) and (7). We also discussed the outflow energy and clump turbulence energy as clumps evolve in slide (8) and (9).
    Copyright© Yang et al. 2018 & Yang et al. 2021b

    Project II--- The birth of HII regions

    When a massive star has “switched on” its UV illumination and ionised the surroundings gas to form an ionised region, i.e., HII region. As massive stars reach the main sequence while still accreting material, the youngest and most compact HII region is a key phase to investigate the early development of massive stars. Hyper-compact HII regions (HCHII) are commonly known as the youngest and densest HII regions, however, To date, only a few of HCHII regions have been discovered and many details remain unknown. To find new HCHII region candidates,

  • We undertook the largest search of HCHII regions using data from Galactic plane surveys of Radio ( CORNISH, MAGPIS, and THOR), submillimeter ATLASGAL, and far-infrared Hi-GAL, mid-infrared MIPSGAL and GLIMPSE, and near-infrared UKIDSS, and obtained a sample of 120 HCHII regions candidates ( Yang et al. 2019).
  • We observed the 120 candidates at X-band and K-band continuum (JVLA17A-070, JVLA18B-065, PI: Aiyuan Yang), to build their spectral energy distribution (SED) between 1-26 GHz, and measure their properties from the SED. Finally, we identified 16 HCHII regions with 7 newly reported, enlarged the sample size by 0.5, giving 23 HCHII regions in total Yang et al. 2021a.
    • The youngest HII regions, HCHII regions, are distinguished from the next class, ultra-compact HII,(UCHII) regions, primarily because they show extremely broad radio recombination lines (RRLs). Thus, RRL is the key to understanding the nature of HCHII regions. To study the RRL in details,
  • we conducted RRL surveys for a sample of 120 HCHII regions and UCHII regions using PI data from the APEX, IRAM 30m, and Effelsberg 100m telescopes, and the RRL observations at high-resolutions (0.2''-1'') using JVLA toward HCHII regions.
    • Young HII regions: HCHII and UCHII
    Slide (1) shows the expected detection level of HII regions in the radio surveys. The multiband emission of young HII regions in slide (2). Slide (3) shows the continumm at C-band, X-band, and K-band, and build the radio SED in slide (4). Slide (5) shows the distribution of physical properties, and their evolution from HCHII regions to UCHII regions. Slide (6) shows the multi-band emission properties of HCHII regions, marked with masers. The early evolution of HII regions are presented in slide (7). Slide (8) shows the luminosity against lyman continuum flux of young HII regions, indicating possible radio jets and dust absorption.
    Copyright© Yang et al. 2019, MNRAS, 482, 268 & Yang et al. 2021,A&A, 645, 110

    Project III---Young Planetary nebulae: kinematic distance and masers

    ISM gas photoionized by low-mass central stars also forms HII regions, called planetary nebulae (PNe). So the physics governing PNe are basically the same as HII regions, with rising radio spectra for free-free emission. The formation of PNe is one of the most poorly understood stages of stellar evolution. The presence of maser emissions are not expected in PNe unless these are extremely young. To date, only five PNe with H2O maser and seven PNe with OH maser have been confirmed ( Zhang 2017). Maser-emitting PNe are thus closely related to the formation and early evolution of PNe
    However, the distances of young PNe are not well determined. Among the total of 3500 PNe ( Kwitter et al. 2014), only about 30 PNe have distance measurements with uncertainties less than 20% ( Yang et al. 2015). Owing to the broadly distributed HI and CO emission, we measured the kinematic distances of young and radio bright PNe, using the method in Tian&Leahy 2008 to resolve the distance ambiguity, giving distance uncertainties ranging from 10% to 50%. This is a significant improvement with uncertainties of a factor of two or three smaller than most previous distance measurements for the young PNe with high extinction in the Galactic Plane ( Yang et al. 2016).

    Young Planetary nebulae: Distances and Masers
    Copyright© Yang et al. 2015, PrA, 33, 284 & Yang et al. 2016, ApJS, 223, 6

    Publications

    NASA/ADS ORCID Proposals

    1. Jun Yang; Yongjun Chen, Leonid I. Gurvits; Zsolt Paragi, A. Y. Yang, Xiaolong Yang and Zhiqiang Shen; "Structural and spectral properties of Galactic plane variable radio sources" ; 2021, MNRAS, In Press;
    2. Urquhart, J. S. ; Wells, M. R. A. ; Pillai, T. ; Leurini, S. ; Giannetti, A. ; Moore, T. J. T. ; Thompson, M. A. ; Figura, C. ; Colombo, D. ; A. Y. Yang; Koenig, C. ; Wyrowski, F. ; Menten, K. M. ; Rigby, A. J. ; Eden, D. J. ; Ragan, S. E. "ATLASGAL -- Evolutionary trends in high-mass star formation" ; 2021, MNRAS, In Press;
    3. D. Colombo, A. Duarte-Cabral, A. R. Pettitt, J. S. Urquhart, F. Wyrowski, T. Csengeri, K. R. Neralwar, F. Schuller, K. M. Menten, L. Anderson, P. Barnes, H. Beuther, L. Bronfman, D. Eden, A. Ginsburg, T. Henning, C. König, M.-Y. Lee, M. Mattern, S. Medina, S. Ragan, A. J. Rigby, Á. Sánchez-Monge, A. Traficante, A. Y. Yang, M. Wienen, "The SEDIGISM survey: the influence of spiral arms on the molecular gas distribution of the inner Milky Way" ;2021, A&A, In Press;
    4. A. Y. Yang; Urquhart, J. S.; Thompson, M. A.; Menten, K. M. ; Wyrowski, F.; & The SEDIGISM Team, 2021; "The SEDIGISM survey: a search for molecular outflows" ; 2021, A&A, In Press;
    5. A. Y. Yang; Urquhart, J. S. ; Thompson, M. A.; Menten, K. M. ; Wyrowski, F. ; Brunthaler, A. ; Tian, W. W.; Rugel, M. ; Yang, X. L. ; Yao, S. ; Mutale, M.; "A population of hypercompact HII regions identified from young H II regions" ; 2021, A&A, 645A, 110Y;
    6. Brunthaler, A.; Menten, K. M. ; Dzib, S. A. ; Cotton, W. D. ; Wyrowski, F. ; Dokara, R.; Gong, Y. ; Medina, S. -N. X. ; Müller, P. ; Nguyen, H. ; Ortiz-León, G. N. ; Reich, W. ; Rugel, M. R. ; Urquhart, J. S.; Winkel, B. ; A. Y. Yang; Beuther, H. ; Billington, S. ; Carrasco-Gonzalez, C.; Csengeri, T. Murugeshan, C.; Pandian, J. D. ; Roy, N.; "A global view on star formation: The GLOSTAR Galactic Plane Survey. I. Overview and first results for the Galactic longitude range: 28◦ < l < 36◦" ;2021, A&A, 651A, 85B; MPIFR/NRAO press release;
    7. Ortiz-León, Gisela N.; Menten, Karl M.; Brunthaler, Andreas; Csengeri, Timea ; Urquhart, James S.; Wyrowski, Friedrich; Gong, Yan; Rugel, Michael R.; Dzib, Sergio A.; A. Y. Yang; Nguyen, Hans; Cotton, William D. ; Medina, Sac Nicté X. ; Dokara, Rohit; König, Carsten; Beuther, Henrik; Pandian, Jagadheep D.; Reich, Wolfgang; Roy, Nirupam; "A Global View on Star Formation: The GLOSTAR Galactic Plane Survey III. 6.7 GHz Methanol maser survey in Cygnus X" , A&A, 651, A87; MPIFR/NRAO press release;
    8. Nguyen, H.; Rugel, M. R.; Menten, K. M. ;Brunthaler, A. ; Dzib, S. A. ; A. Y. Yang; Kauffmann, J.; Pillai, T. G. S. ; Nandakumar, G. ; Schultheis, M. ; Urquhart, J. S.; Dokara, R.; Gong, Y. ; Medina, S. -N. X. ; Ortiz-León, G. N. ; Reich, W. ; Wyrowski, F. ; Beuther, H. ; Cotton, W. D. ; Csengeri, T. Pandian, J. D. ; Roy, N.; "A global view on star formation: The GLOSTAR Galactic plane survey IV. Radio continuum detections of young stellar objects in the Galactic Centre region" , 2021; A&A, 651, A88, MPIFR/NRAO press release
    9. Dokara, R.; Brunthaler, A.; Menten, K. M.; Dzib, S. A.; Reich, W.; Cotton, W. D.; Anderson, L. D.; Chen, C. -H. R.; Gong, Y.; Medina, S. -N. X.; Ortiz-León, G. N.; Rugel, M.; Urquhart, J. S.; Wyrowski, F.; A. Y. Yang; Beuther, H.; Billington, S. J.; Csengeri, T.; Carrasco-González, C.; Roy, N.; "A global view on star formation: The GLOSTAR Galactic plane survey. II. Supernova Remnants in the first quadrant of the Milky Way" , 2021, A&A, 651, A86, MPIFR/NRAO press release ;
    10. Eden, D. J., ..., A. Y. Yang, ..., & The CHIMPS Team; "CHIMPS2: survey description and 12CO emission in the Galactic Centre" , 2020, MNRAS, 498, 5936E;
    11. Shan, Su-Su; Zhu, Hui; Tian, Wen-Wu ; Zhang, Hai-Yan ; A. Y. Yang; Zhang, Meng-Fei; "The distance measurements of supernova remnants in the fourth Galactic quadrant" , 2019, RAA, 19, 92S;
    12. A. Y. Yang; Thompson M. A.; W. W. Tian, S. Bihr; H. Beuther; L. Hindson; "A search for hyper-compact HII regions in the Galactic Plane" , MNRAS, 482, 2681Y, 2019;
    13. Shan, S. S.; Zhu, H.; Tian, W. W.; Zhang, M. F.; Zhang, H. Y.; Wu, D.; A. Y. Yang; Zhang, Meng-Fei; "Distances of Galactic Supernova Remnants Using Red Clump Stars" , 2019, ApJS, 236, 35S;
    14. A. Y. Yang; Thompson M. A.; Urquhart J.S.; W. W. Tian; "Massive Outflows Associated with ATLASGAL Clumps" , 2018, ApJS, 235, 3;
    15. A. Y. Yang; W. W. Tian; H. Zhu; D. Wu; "Kinematic Distances of Galactic Planetary Nebulae"; 2016, ApJS, 223, 6;
    16. Thompson M. A.; ...; A. Y. Yang; ...; "MeerGAL: the MeerKAT Galactic Plane Survey";2016;
    17. A. Y. Yang; H. Zhu; W. W. Tian; D. Wu; "The Current Research of Planetary Nebulae Distance"; 2015, Progress in Astronomy (Chinese),33, 284;
    18. A. Y. Yang; J. L. Han; N. Wang; "A New Method to Analysis Pulsar Nulling Phenomena", 2014, SCIENCE CHINA Physics, Mechanics & Astronomy, 57(8), 1600-1606;