Chengyuan LI: The VMC Survey. XII. Radial Stellar Population Gradients in the Galactic Globular Cluster 47 Tucanae

TitleThe VMC Survey. XII. Radial Stellar Population Gradients in the Galactic Globular Cluster 47 Tucanae

Speaker: Chengyuan LI (DoA/KIAA-PKU)

Time: Friday, March 7, 3pm-5pm

Place: A408, NAOC 

We present a deep near-infrared color–magnitude diagram of the Galactic globular cluster 47 Tucanae, obtained with the Visible and Infrared Survey Tele- scope for Astronomy (VISTA) as part of the VISTA near-infrared Y, J, Ks survey of the Magellanic System (VMC). The cluster stars comprising both the subgiant and red giant branches exhibit distinct, continuous variations in color–magnitude space as a function of radius. Subgiant-branch stars at larger radii are systemati- cally brighter than their counterparts closer to the cluster core; similarly, red giant branch stars in the cluster’s periphery are bluer than their more centrally located cousins. The observations can very well be described by adopting radial gradients in both the cluster’s helium abundance (Y) and metallicity (Z), which gradually change from (Y = 0.28, Z = 0.009) in the cluster core to (Y = 0.25, Z = 0.003) in its periphery. We conclude that the cluster’s inner regions host a significant fraction of second-generation stars, which decreases with increasing radius.

Next Teeminars

Time Plan 2019/2018/2017


Time and Place: Friday; 3:00 - 5:00 p.m., NAOC (unless noted otherwise); tbc = to be confirmed

  • March 19: (KIAA, 2nd floor meeting room, note unusual Tuesday!):

Pau Amaro-Seoane (ICE, KIAA): X-MRIs: Extremely large mass-ratio inspirals
Fupeng Zhang (Zhongshan U): Binary Black Holes in Galactic Nuclei
Tai Zhou (KIAA): Binary Extreme Mass Ratio Inspiral Numerical Simulation

  • March 12: (note unusual Tuesday!)

Arkadiusz (Arek) Hypki (A. Mickiewicz U, Poznan, Poland): On BEANS and simulation data

  • March 8:

Mohammed Mardini (NAOC): Decoding the history of our universe using carbon-enhanced metal-poor star                                                             

Bhusan Kayastha (NAOC)/Albrecht Kamlah (NAOC/U Göttingen, Germany): progress report

Time and Place: 3:00 - 5:00 p.m., NAOC (unless noted otherwise); tbc = to be confirmed
  • Dec. 25: (note unusual Tuesday!): Sambaran Banerjee (Argelander Inst., Univ. Bonn, Germany): Stellar-mass black holes in open clusters: implications for gravitational-wave generation
  • Dec. 21: no tea seminar, MIDAS meeting
  • Dec. 11 (note unusual Tuesday!): Kohei Inayoshi (KIAA): Black hole accretion in the present-day and early universe; and general discussion on supercomputing in China
  • Dec. 7: no tea seminar, KCK10 at Suzhou
  • Nov. 30: no tea seminar
  • Nov. 23: Agostino Leveque (CAMK, Poland): The C MOCCA version: a step toward AMUSE
  • Nov. 16: Discussion with Mirek Giersz (CAMK, Poland)
  • Nov. 9: Sergey Khoperskov (Moscow/Garching)
  • Oct. 19/Nov. 2: no tea seminar
  • Oct. 12:
  • Oct. 5: vacation?
  • Sep. 28:Jongsuk Hong (KIAA): Stellar Evolution in Star Clusters: Applications
  • Sep. 21: Rainer Spurzem (NAOC): Discussion Meeting on Status of Stellar Evolution in NBODY simulations
  • Sep. 14: Planning Session and Reports
  • May 18: Shuo Li (NAOC): Multi-mass galaxy merger simulations




  • Dec. 15: note location and changed speaker: at KIAA Room 208: Shu Qi: Dynamic evolution of free-floating comets in star cluster / Taras Panamarev: N-body model of galactic center
  • Dec. 8: Li Shuo: Tidal disruption in galaxy mergers with Multi-mass and stellar evolution model.
  • Nov. 17: Verónica Vázquez: The merger of two quarks stars. A SPH Newtonian simulation
  • Oct. 27: Mirek Giersz (CAMK Warsaw, Poland): MOCCA - Survey Data Base - Projects (Black Holes and Gravitational Waves from Star Clusters)
  • Oct. 25 Lunch Seminar at KIAA (12:00 p.m.): Holger Baumgardt (Queensland Univ., Australia): The formation of the smallest galaxies
  • Oct. 20: Bohdan Novosyadlyj & Valerii Shulga (Ivan Franko Natl. Univ. of Lviv, Ukraine and Jilin Univ. China): Dark matter and dark energy probes: from Dark Ages to Giant Voids
  • Sep. 15: Xiaoying Pang: Open clusters from SDSS DR 14 | Bai Jing: Short Report on Galev Work | Rainer Spurzem: Short Status Report and Discussion of DRAGON Data Project
    • Sep. 7: Yohai Meiron (Eötvös University, Budapest, Hungary):  Relaxation and mixing of constants of motion in globular clusters
  • Sep. 1: Planning Meeting (Tea Seminar, Conferences, Travel)
      • Next Seminars:

  • Dec. 22: No tea seminar (KCK9)
  • Dec. 29:?


———Summer Break——————————————————

  • May 5: no tea seminar (Lazenby KIAA colloquium overlaps)
  • May 12: Alexandr Zhuk (Odessa  National University, Ukraine and Jilin University, China):  Cosmic screening of the gravitational interaction in the Universe (Abstract)
  • May 19: Xian Chen (DoA, PKU):   Retrieving the rest mass of GW150914  and Rainer Spurzem (Silk Road NAOC): News on NBODY6++GPU and Galactic Center DRAGON



  • Oct. 28: no tea seminar (EANAM7)
  •     Nov. 4: no tea seminar (CAS2016 Wuhan)
  •     Nov. 11: no tea seminar (KIAA Astro Forum)
  •     Nov. 14: DoA/PKU Lunch Talk: Abbas Askar: Monte Carlo Models
  •     Nov. 18: Li Shuo: Binary Black Holes in Merging Galaxies
  •     Nov. 25/Dec. 2: no tea seminar (China/South Africa workshop)
  •     Dec. 9: Matthias Kühtreiber: Galaxy Evolution Models
  •     Dec. 16: Shu Qi: Comets and Planets in Star Clusters/Taras Panamarev: N-Body models of Galactic Center
  •     Dec. 23: Jongsuk Hong: Multiple Populations in star clusters
  •     Dec. 28: Shuo Li: postponed to next year


Past Seminars in this period:


  • Sep. 16 Discussion Meeting with Guests
    1.) Thijs Kouwenhoven, Xian Jiaotong/Liverpool Univ. at Suzhou:
    Disk fragmentation and brown dwarfs in the Galactic field
     2.) Xiaoying Pang, Shanghai Inst. of Technology, on open clusters
     3.) Yohai Meiron, Eoetvoes Univ. Budapest, Hungary, on stellar disks in AGN
  • Sep. 23 at Room 410, Morningside Center of Mathematics near AMSS/CAS (location see link), 4:00 p.m.: Yohai Meiron, Eötvös University (Budapest, Hungary)Triple companion in gravitational wave signals (Abstract) (notice: postponed: Fabian Klein on Initial Models for AGN Disks using pluto)



Past Seminars