Herbig-Haro
objects are
small-scale shock regions, associated with the jets produced by young protostars.
They have characteristic spectra which set them apart from photo-ionized
regions.
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here
to learn more about them.
T-Tauri stars are low-mass pre-main-sequence objects that represent a transition between stars that are still shrouded in dust and main-sequence stars.
Stellar wind: a steady stream of plasma which flows away from a star along magnetic field lines. It is composed of charged particles such as protons, electrons and the atomic nuclei of helium.
Shock
waves: compressions
which propagate through a medium at a velocity greater than that of sound
in the medium.