ALMA-IMF X – The core population in the evolved W33-Main (G012.80) protocluster
arxiv(2024)
摘要
We aimed to measure the CMF in the evolved W33-Main star-forming protocluster
to compare it with CMF recently obtained in other Galactic star-forming
regions, including the ones included in the ALMA-IMF program. We used
observations from the ALMA-IMF large program: 2'x2' maps of emission from the
continuum and selected lines at 1.3mm and 3mm observed by the ALMA 12m only
antennas. Our angular resolution was typically 1”, that is 2400au at a
distance of 2.4kpc. The lines we analysed are CO(2-1), SiO(5-4), N2H+(1-0),
H41alpha as well as He41alpha blended with C41alpha. We built a census of dense
cores in the region, and we measured the associated CMF based on a
core-dependent temperature value. We confirmed the 'evolved' status of W33-Main
by identifiying three HII regions within the field, and to a lesser extent
based on the number and extension of N2H+ filaments. We produced a filtered
core catalog of 94 candidates, that we refined to take into account the
contamination of the continuum by free-free and line emission, obtaining 80
cores with masses that range from 0.03 to 13.2Msun. We fitted the resulting
high-mass end of the CMF with a single power law of the form N(log(M))
M^alpha, obtaining alpha = -1.44(+0.16)(-0.22), slightly steeper but consistent
with the Salpeter index. We categorized our cores in pre- and protostellar,
mostly based on outlow activity and hot core nature. We found the prestellar
CMF to be steeper than a Salpeter-like distribution, and the protostellar CMF
to be slightly top heavy. We found a higher proportion of cores within the HII
regions and their surroundings than in the rest of the field. We also found
that the cores' masses were rather low (maximum mass of 13Msun).
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