148 research outputs found
A Census of Outflow to Magnetic Field Orientations in Nearby Molecular Clouds
We define a sample of 200 protostellar outflows showing blue and redshifted
CO emission in the nearby molecular clouds Ophiuchus, Taurus, Perseus and Orion
to investigate the correlation between outflow orientations and local, but
relatively large-scale, magnetic field directions traced by Planck 353 GHz dust
polarization. At high significance (p~1e-4), we exclude a random distribution
of relative orientations and find that there is a preference for alignment of
projected plane of sky outflow axes with magnetic field directions. The
distribution of relative position angles peaks at ~30deg and exhibits a broad
dispersion of ~50deg. These results indicate that magnetic fields have
dynamical influence in regulating the launching and/or propagation directions
of outflows. However, the significant dispersion around perfect alignment
orientation implies that there are large measurement uncertainties and/or a
high degree of intrinsic variation caused by other physical processes, such as
turbulence or strong stellar dynamical interactions. Outflow to magnetic field
alignment is expected to lead to a correlation in the directions of nearby
outflow pairs, depending on the degree of order of the field. Analyzing this
effect we find limited correlation, except on relatively small scales < 0.5 pc.
Furthermore, we train a convolutional neural network to infer the inclination
angle of outflows with respect to the line of sight and apply it to our outflow
sample to estimate their full 3D orientations. We find that the angles between
outflow pairs in 3D space also show evidence of small-scale alignment.Comment: ApJ Accepte
Co-Evolution of Stars and Gas: Using Analysis of Synthetic Observations to Investigate the Star-Gas Correlation in STARFORGE
We explore the relationship between stellar surface density and gas surface
density (the star-gas or S-G correlation) in a 20,000 M simulation
from the STAR FORmation in Gaseous Environments (STARFORGE) Project. We create
synthetic observations based on the Spitzer and Herschel telescopes by modeling
active galactic nuclei contamination, smoothing based on angular resolution,
cropping the field-of-view, and removing close neighbors and low-mass sources.
We extract star-gas properties such as the dense gas mass fraction, the Class
II:I ratio, and the S-G correlation () from
the simulation and compare them to observations of giant molecular clouds,
young clusters, and star-forming regions, as well as to analytical models. We
find that the simulation reproduces trends in the counts of young stellar
objects and the median slope of the S-G correlation. This implies that the S-G
correlation is not simply the result of observational biases but is in fact a
real effect. However, other statistics, such as the Class II:I ratio and dense
gas mass fraction, do not always match observed equivalents in nearby clouds.
This motivates further observations covering the full simulation age range and
more realistic modeling of cloud formation.Comment: 25 pages, 16 figures. To be published in The Astrophysical Journa
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