  Physical properties of ten millimeter-sized meteoroids from the Southern
Delta Aquariids (SDA) shower are derived using optical observations from the
Canadian Automated Meteor Observatory between 2020 and 2023. The meteors are
found to ablate in two distinct erosion stages, the second stage showing a
single, bright leading fragment. Our modelling interprets these observations as
evidence for equal masses of compact grains embedded in a porous, low density
matrix. The average bulk density of SDA meteors is found to be 1,420 $\pm$ 100
$\rm{kg \ m^{-3}}$, with the compact component having a density of 2,310 $\pm$
160 $\rm{kg \ m^{-3}}$ and the porous component a density of $700\pm110$
$\rm{kg \ m^{-3}}$. The high bulk density of SDA meteors is comparable to
densities found for the Quadrantid and Geminid showers, both of which also have
low perihelion distances. This suggests that thermal desorption may play a
significant role in the processing of meteoroids.
