Abstract
Sulfur is abundant in the universe and on Earth, produced in stellar cores and crucial for life. While sulfur is
highly depleted in dense molecular clouds, sulfur-bearing species are effective probes of the physical conditions
of various energetic environments. In this seminar, I will discuss our recent studies on sulfur-bearing species in
star-forming regions. With low-mass protostars, we reveal their structures and physical conditions using volatile
species (e.g., SO). Moreover, we probe the ‘hot disks’ of massive protostars, where the dust is sublimated and a
high fraction of sulfur is released back to the gas-phase, with refractory species (e.g., SiS). Such studies would
not only assist in probing the physical and chemical properties of young stellar objects, but also better our
understanding of the high depletion rate of sulfur- the ‘missing sulfur’ problem. Furthermore, solid evaporation
in the “hot disks” drops a hint of the formation of primitive meteorites and thus the origin of our solar system.
