About the PI

Yueh-Ning Lee

2022/08- Associate professor, Department of Earth Sciences, National Taiwan Normal University
2020/10- Deputy director, Center of Astronomy and Gravitation, NTNU
2021/01-2022/12 Center Scientist, National Center for Theoretical Sciences
2019/08-2021/07 Assistant professor, Department of Earth Sciences, National Taiwan Normal University
2017-2019 Postdoctoral researcher, Insititut de Physique du Globe de Paris
2014-2017 Ph.D. in Astronomy and Astrophysics, Paris Direrot University/ DAp, CEA Saclay
2013-2014 M.Sc. in Astronomy and Astrophysics, ENS Paris, Observatory of Paris

I am an astrophysicist. My main interest is to understand how star forms from the diffuse medium, which we call the molecular cloud. Stars are fundamental building blocks of the universe, and one of their key characteristics is their mass. The process though which stars acquire their mass involves multiple physical mechanisms such as gravity, thermal pressure, turbulence, magnetic field, radiation, and cosmic rays. I perform numerical simulations of stellar cluster formation and try to understand how mass is distributed into individual stars. I also do detailed simulations of collapse of prestellar cores to understand the formation of individual stars.

JOIN US!

Undergraduate Projects

For undergraduate students, if you like star formation, fluid dynamics, magnetoelectrodynamics, algebra, and solving PDEs, this might be the right place for you. Do not hesitate to contact me!

Intership opportunity for foreign students

Apply for the International Internship Pilot Program (IIPP by the NSTC). Interested students please contact the PI directly to define a project. The program can last for up to 3 months with 30 k NTD subdity/month.

Identifying star-forming cores 13CO emission maps

Multi-tracer surveys have revealed the hierarchical nature of molecular clouds, showing how high- density, small-scale features are always nested within more rarefied, larger envelopes. This structural hierarchy is, however, a non-trivial one: at any scale, there appear to be more high-density and compact `clumps' than larger and less dense structures. The densest clumps in a cloud's hierarchy are compact cores, the seeds of star formation. We used an algorithm based on graph and clustering theory to identify gaseous structures in the CO Heterodyne Inner Milky Way Plane Survey (CHIMPS) emission maps. In this project, we aim to find the densest cores in this emission segmentation and match them with infra-red luminosities measured independently in the Herschel infrared Galactic Plane Survey (Hi-Gal).
  • Infra-red emission (along with mass) is a proxy for star formation efficiency in molecular clouds.
  • Some basic knowledge in astronomical observation and python programming is preferable. This project can be part of the Earth Sciences Suummer Student Program (ESSSP) during the summer (July and August). Interested students can start as early as possible.
  • Contact: Dr. Raffaele Rani (rani@ntnu.edu.tw)

Finding filaments in Galactic plane molecular clouds

Filaments are ubiquitous structures found in dense molecular clouds. Whether they are considered a mere result of turbulence upon cloud formation or the main channels along which mass is transported to compact cores, their nature and importance are not fully understood. In this project, we will attempt to identify filaments in a suitable set of clouds in the CO Heterodyne Milky Way Plane Survey (CHIMPS) and its follow-up CHIMPS2 by using filament-finding algorithms. We aim to study the distributions of filament size (in particular their width) in relation to the physical properties of molecular gas.
  • Some basic knowledge in astronomical observation and python programming is preferable. This project can be part of the Earth Sciences Suummer Student Program (ESSSP) during the summer (July and August). Interested students can start as early as possible.
  • Contact: Dr. Raffaele Rani (rani@ntnu.edu.tw)

Exoplanet transit observation using photometry light curves

Exoplanets are amongst the most important research topics of contemporary astronomy. The discovery of exoplanets can be based on various techniques, mostly requiring timedomain observation. The transit light curve is one of the simplest, yet powerful, way to detect exoplanets. During this summer program, we will participate in the ExoClock project by the ARIEL Ephemerides Working Group using the Flat Roof Observatory of the Department of Earth Sciences, NTNU. Students will learn basic observation knowledge and data processing of the exoplanet transit light curve. There are possibilities of carrying on the research project after the end of the summer program.
  • Some basic knowledge in astronomical observation and python programming is preferable.
  • This project can be part of the Earth Sciences Suummer Student Program (ESSSP) during the summer (July and August). The work includes conducting observations during some of the nights. Interested students can start as early as possible.
  • Contact: Prof. Yueh-Ning Lee (ynlee@ntnu.edu.tw)

Self-similar collapse solutions of radiatively cooling gas

The interstellar medium is so diffuse that, when compressed during the collapse, the increased internal energy can be lost through radiation. In consequence, the gas heats up less efficiently than what would have been expected for a gas under adiabatic compression. We will solve the Navier-Stokes equations to find a self-similar collapse solution. With this, an effective equation of state of the gas can be obtained, with which we no longer need explicit expression of the radiative cooling. The spherical collapse solution has been known already, while the student will work on a system of cylindrical or plane-parallel geometry.
  • Some basic knowleged (Python) is required. The student should have already taken courses of fundamental physics and calculus. Introductory courses in astronomy in preferable
  • Contact: Prof. Yueh-Ning Lee (ynlee@ntnu.edu.tw)