I am a fourth-year graduate student at MPIA. I have a physics background and am generally working on interstellar medium, dust extinction, and machine learning
Education:
2021-present, Graduate student @ MPIA
2021, Bachelor's degree of Natural Science @ Dep. of Physics, THU
Research Interests:
Topics: Chemical evolution of the interstellar medium |
3D dust maps of the MW | PAHs
Methods: Machine learning with large spectroscopic and photometric surveys
Instruments: Gaia | JWST | SPHEREx | Rubin/LSST
I come from Baotou, "the city of deers". Besides astronomy, I like spending all day at history museums learning random facts that are fun, such as:
This is how astronomers in 16th century measured stellar coordinates.
(Shot by me in the Ancient Observatory, Beijing, 2018)
Thanks for your like(s)!
Research
Parameters of 220 million stars from Gaia BP/RP spectra
Gaia DR3 contains low-resolution XP spectra of over 220 million stars, giving a unique opportunity to measure dust extinction and its vatiation in 3D.
We build a forward model that maps (Teff, [Fe/H], logg) to Gaia XP, and ultilize this model to determine the stellar types, extinction and distances for all 220 million Gaia XP stars.
For more details, please take a look at
our paper.
Variation of dust extinction in the milky way
The variation of dust extinction is modelled by the parmeter R(V) (โก A(V)/E(B-V) ), which is determined by the size distribution and chemical composition of the interstellar dust. Dust Rv is an also important tracer of local physical and chemical environment, such as SNe, star formation and molecular clouds.
Ultilizing Gaia XP spectra, we determine Rv for ~ 130 million high-extinction stars in the Milky Way, LMC and SMC, which is the largest Rv catalog (zenodo) up to 2024.
This paper is under review, arXiv:2407.14594
Physical explanation of R(V): Is it driven by Polycyclic Aromatic Hydrocarbons (PAHs)?
We find evidence of PAH-driven ๐ (๐) variation observationally and theoretically. The ๐ (๐) value in translucent gas has an anticorrelation with the PAH abundance, as the picture shown above. Growth of PAH strengthens the 2175 ร feature, of which the red wing contributes to B band extinction but is almost negligible to V band, which leads to decrease of ๐ (๐).
If proven, this leads to a revolutionary change on the picture of ๐ (๐) as well as all fields of astronomy that utilize correction of extinction. Notably, Type Ia supernovae are observed to have anomalously low R(V), which could be connected to potential PAH growth in supernova shocks. Our findings also underscore the importance of PAH growth in the ISM, a possibility hinted at by recent PAH emission trends with metallicity.
This paper is under review, arXiv: 2410.23171 .
Talks
(Title, Type, Time, Link & Place)
1. Variation of extrinction curces from PS1, 2MASS, WISE \& Gaia | Interstellar Institute, July 2022 @ Institut Pascal , Saclay
2. Stellar parameters of 220 million stars from Gaia XP spectra | MPIA Science day, December 2022 @ MPIA, Heidelberg
3. Stellar parameters from Gaia XP spectra using a forward model | Gaia XPloration, May 2023 @ IoA, Cambridge
4. A 3D Rv map based on Gaia XP spectra | August 2023 @ DoA, Tsinghua University, Beijing
5. Inferred stellar parameters from 220 million XP spectra using an empirical forward model | NAOC Seminar, August 2023
@ NAOC, Beijing
6. Inferred stellar parameters from 220 million XP spectra using an empirical forward model | KIAA Seminar, August 2023 @ KIAA, PKU, Beijing
