Mass Assembly of Stellar Systems and Their Evolution with the SMA
  (MASSES). Multiplicity and the Physical Environment in L1448N
  We present continuum and molecular line observations at 230 GHz and 345 GHz
from the Sub-millimeter Array (SMA) toward three protostars in the Perseus
L1448N region. The data are from the large project "Mass Assembly of Stellar
Systems and their Evolution with the SMA" (MASSES). Three dust continuum
sources, Source B, Source NW, and Source A, are detected at both frequencies.
These sources have corresponding emission peaks in C18O (J=2-1), 13CO (J=2-1),
and HCO+ (J=4-3), and have offsets with N2D+ (J=3-2) peaks. High angular
resolution data from a complimentary continuum survey with the Karl G. Jansky
Very Large Array show that Source B is associated with three 8 mm continuum
objects, Source NW with two, and Source A remains single. These results suggest
that multiplicity in L1448N exists at different spatial scales from a few
thousand AU to < 100 AU. Velocity gradients in each source obtained from
two-dimensional fits to the SMA C18O emission are found to be perpendicular to
within 20 degrees of the outflow directions as revealed by 12CO (J=2-1). We
have observed that Sources B and NW with multiplicity have higher densities
than Source A without multiplicity. This suggests that thermal Jeans
fragmentation can be relevant in the fragmentation process. However, we have
not observed a difference in the ratio between rotational and gravitational
energy between sources with and without multiplicity. We also have not observed
a trend between non-thermal velocity dispersions and the level of
fragmentation. Our study has provided the first direct and comprehensive
comparison between multiplicity and core properties in low-mass protostars,
although based on small number statistics.
