Mira variables from LAMOST
Mira stars are a class of long period variables in the very late stages of stellar evolution.
Based on their spectroscopic characteristics, I found 191 new Mira candidates from millions of spectra in the LAMOST DR4 catalogue.
In addition, I derived a relationship between relative Balmer emission-line strength and spectral temperature of Oxygen-rich Mira stars. The relative flux of higher orders in the Balmer series (Hdelta) increases as stars cool down from M0 to M10, which is likely driven by increasing TiO absorption above the deepest shock-emitting regions.
Searching for quasars behind
Andromeda with PTF
Following Sumin Tang's work in 2013, I work as a SURF student in the summer of 2017 to search for quasars behind the Andromeda Galaxy (M31) with variability data from the Palomar Transient Factory (PTF).
Based on Machine Learning (ML) algorithms, I used 59 known quasars and 200 known stars as a training set to build the “star-quasar” separation filter, which selected 120 quasar candidates. I obtained spectra for 54 candidates using the Palomar 5-m and Keck 10-m telescopes, and 49 of them were confirmed to be bona fide quasars.
Evolution of primordial disks:
depend on stellar mass and age
The goal of this project is to quantify the lifetime of gas-rich
circumstellar disks around young stars as a function of host star mass.
The lifetime of gas-rich disks sets a
limit to the timescale available for gas giant planet formation
(and seeding atmospheres of lower mass planets as well from primordial gas).
Constraining this timescale as a function of stellar mass would be
a major constraint on theories of planet formation.
Moreover, we also provide the most robust evidence to date for
disk evolution within clusters exhibiting modest age spreads.