New PARSEC database of alpha enhanced stellar evolutionary tracks and isochrones for Gaia
I'm working with Prof. Alessandro Bressan
and Padova stellar group on PARSEC (the PAdova & TRieste Stellar Evolution
Code). We are now preparing a new database of alpha enhanced evolutionary tracks and isochrones.
The new isochrones are tested against Color-Magnitude Diagrams of well studied Globular Clusters,
tacking into account multiple population effects. They are also compared with observations of dwarf stars in the Solar vicinity.
After these preliminary computations, we will provide the full sets of isochrones with chemical compositions suitable for Globular Clusters and Bulge stars,
that will be fully implemented into galaxy simulators. We will also provide new models suitable for the analysis of unresolved stellar populations
in early type galaxies.
Lithium abundance derived in metal-poor main-sequence stars is about three times lower than the value of primordial Li
predicted by the standard big bang nucleosynthesis. This disagreement is generally referred as the lithium problem.
We reconsider the stellar Li evolution from the pre-main sequence (PMS) to the end of the MS phase by introducing the effects
of convective overshooting and residual mass accretion. we reproduce the Spite plateau for stars with initial mass m0 = 0.62-0.80 M⊙,
and the Li declining branch for lower mass dwarfs, e.g. m0 = 0.57-0.60 M⊙, for a wide range of metallicities (Z = 0.00001 to Z = 0.0005),
starting from the primordial Li abundance A(Li) = 2.72 (Fu, et al, 2015).
This environmental Li evolution model also offers the possibility to interpret the
decrease of Li abundance in extremely metal-poor stars,
the Li disparities in spectroscopic binaries and the low Li abundance in planet hosting stars.
Stars destroy lithium in their normal evolution. The convective envelopes of evolved red giants reach temperatures of millions of kelvin,
hot enough for the 7Li(p, α)4He reaction to burn Li efficiently.
Only about 1% of first-ascent red giants more luminous than the luminosity function bump in the red giant branch exhibit A(Li) > 1.5.
Nonetheless, Li-rich red giants do exist. We discoveried 14 Li-rich red giants among a sample of 2054
red giants in Milky Way dwarf satellite galaxies (Evan Kirby, Xiaoting Fu, Puragra Guhathakurta & Licai Deng, 2012, ApJ, 752, L16).
Because most of the stars have Li abundances larger than the universe's primordial value,
the Li in these stars must have been created rather than saved from destruction.
These Li-rich stars appear like other stars in the same galaxies in every measurable regard other than Li abundance.
I'm interested in the nature of these Li-rich red giant stars, and now working both on the observation and theory to investigate the mechanism.
I was in the LAMOST-PLUS group when I was a master student,
working on the stellar stream in the Milky Way halo. Now I'm a Gaia member.
I'm interested in the chemical evolution and the structure of our galaxy.
Lithium evolution from Pre-Main Sequence
to the Spite plateau: an environmental
solution to the cosmological lithium problem
Gaia-ESO Survey 3rd science meeting • Conference oral talk •Vilnius, Lithuania, December 3, 2015 ESO • lunch talk •Garching, Germany, November 10, 2015 KIAA at Peking University • lunch talk • Beijing, China, December 21, 2015
New PARSEC database of alpha enhanced stellar evolutionary tracks and isochrones for Gaia
IAU GA FM7 • Conference oral talk •Hawaii, USA, August 2015
Lithium problems: on the main sequence and the red giant branch
The University of Science and Technology of China (USTC) • Invited talk •Hefei, China, December 2015 Shanghai Astronomical Observatory • Invited talk •Shanghai, China, December 2014 Nanjing University • Invited talk •Nanjing, China, December 2014
The discovery of 14 lithium-rich red giants in Milky Way dwarf satellite galaxies
Lithium in the Cosmos • Conference oral talk •Institut d'Astrophysique de Paris, France, February 2012 LAMOST - PLUS workshop • Conference oral talk •Rensselaer Polytechnic Institute, New York, USA, June 2011
Education
Ph.D., Astrophysics
International School for Advanced Studies (SISSA)• Trieste, Italy
November 2012 - October 2016
Thesis: Evolution of low mass stars : lithium problem and α-enhanced tracks and isochrones.
[download] advisor: Alessandro Bressan, Paolo Molaro, Léo Girardi
M.S., Astrophysics
National Astronomical Observatories of China (NAOC)•Beijing, China
September 2009 - June 2012 advisor: Licai Deng
B.S., Optical Information Science and Technology
Beijing Jiaotong University (BJTU)•Beijing, China
September 2004 - June 2008
AWARDS
Bronze poster prize
ESO “RUSPUTIN” conference•October 2014
Lithium evolution in POP II pre-main sequence stars with overshoot and accretion
The best runner-up poster prize
IAUS 298 •May 2013
Discovery of super-Li rich red giants in Dwarf Spheroidal galaxies
Student merit award
Graduate University of Chinese Academy of Sciences•July 2012; July 2010
FELLOWSHIPS
SISSA PhD fellowship
International School for Advanced Studies (SISSA)•Nov 2012 - present
CAS Graduate assistantship
Chinese Academy of Sciences (CAS)•Sep. 2009 - Jun. 2012
Observation
experience
Keck II - DEIMOS
Mauna Kea, USA•March 3-5, 2011
Hale telescope - DBSP
Palomar, USA•April 4-6, 2011
2.16m telescope - HRS
Xinglong, China•December 12-15, 2011
LAMOST
Xinglong, China•October 16-18, 2012; February 23-27, 2011
Those pleasure that science gives to me,
I would love to share with everyone.
Sharing the beauty of science to public is always my pleasure.
I have published several articles in amateur astronomer magazines.
I also have rich experiences of giving popular science talks in planetarium,
high school, and other public events.
AND... if you are interested in, here is also a Youtube video of the song I sang in front of Galileo Galilei's house in Padova,
where he uesed his telescopes to observe the sky for the first time in the history of humankind, 1609. The song "shoulders of giants" (in English).
