Joao Lin Yun
João Lin Yun
To obtain this document in Portuguese please click here.
Last update on: 2002 July 17
As a member of the Center for Astronomy & Astrophysics, and researcher of the Observatório Astronómico
de Lisboa, and as staff Professor
Physics Department of the Faculdade
de Ciências of the University of Lisbon, I teach courses of the
Physics BS degree and of the Master's degree in Astronomy and Astrophysics.
I can be reached at my office's address:
Observatório Astronómico de Lisboa
Tapada da Ajuda
1349-018 Lisboa, PORTUGAL
Telefone: 21 361 6739
FAX: 21 361 6752
or through E-mail: Joao.Yun "at" oal.ul.pt
Research activity in:
Star Formation. Young Stellar Objects. Protostars.
Circumstellar matter. Disks. Young Stellar Clusters.
Composition, Structure and Evolution of the
Interstellar Medium. Filamentary Dark Clouds.
Small molecular clouds. Bok globules.
Techniques of Millimeter, Infrared and Optical
The line of research that I have been exploring with BSc., MSc., and PhD. students, is focused on the study of the physical conditions and stellar content of molecular
We use techniques of optical, infrared and radio astronomy in the following
lines of research:
Line 1: Young stellar objects embedded in molecular clouds.
- Using near-infrared array images, we explore the interior of dark molecular clouds. We have discovered stars in the process of formation still embedded in
their parent molecular cloud. Many of these stars are surrounded by
circumstellar disks revealed by color excesses in the infrared and by spectral
energy distributions distinct from those of a blackbody.
Similarly, objects in later stages of evolution, closer to the main-sequence,
are optically visible. Spectra of these objects allow us to confirm their
T Tauri star character. CCD images of these regions were used to search for the
presence of HH objects and optical jets in the vicinity of the young stars.
Line 2: Structure and physical conditions in molecular clouds.
- We use techniques in Radio-Astronomy to map molecular clouds in the line
transitions of a few molecular species present in the Interstellar Medium.
This maps allow us to study the distribution of temperature and density in this
clouds, as well as the velocity fields, providing information to analyze their
stability and potential to form stars.