Variability of the Balmer Emission Lines in T Tauri Stars

Classical T Tauri stars (CTTSs) are young, roughly solar mass, pre
main sequence stars (PMS) that have only recently emerged from their
natal molecular cloud cores to become optically visible.  Most, if not
all, low mass stars, including the Sun, go through a CTTS stage in the
first few million years after they are born.  It is during this time
that planets form in the accretion disks that are found around CTTSs.
In addition to forming planets, most of the material in the disks either
accretes onto the star or is removed in an outflow, but the exact nature
of these flows remains poorly understood.  The Balmer emission lines of
CTTSs form in these accretion and wind flows, and the strength and
shape of the Balmer emission lines varies substantially with time,
offering a means to better understand these flows.  Here, we analyze
the variability of the main Balmer lines in the CTTS BP Tau in order
to better understand the accretion and wind flows of this young star.