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Dense gas in molecular clouds is an important signature of ongoing and future star formation. We identify and track dense cores in the Starforge simulations, following the core evolution from birth through dispersal by stellar feedback for typical Milky Way cloud conditions. Only ∼8% of cores host protostars, and most disperse before forming stars. The median starless and protostellar core lifetimes are ∼0.5–0.6 Myr and ∼0.8–1.1 Myr, respectively, where the protostellar phase lasts 0.1 Myr. While core evolution is stochastic, we find that virial ratios and line widths decline in prestellar cores, coincident with turbulent decay. Collapse occurs over ∼0.1 Myr, once the central density exceeds ≳106cm−3. Starless cores, only, follow line-width–size and mass–size relations,σ∝R0.3andM∝R1. The core median mass, radius, and velocity dispersion scale weakly with the cloud magnetic field strength. We cluster the core properties and find that protostellar cores have >80% likelihood of belonging to three particular groups that are characterized by high central densities, compact radii, and lower virial parameters. Overall, core evolution appears to be universally set by the interplay of gravity and magnetized turbulence, while stellar feedback dictates protostellar core properties and sets the protostellar phase lifetime.
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3D radiative transfer modelling and virial analysis of starless cores in the B10 region of the Taurus molecular cloud
ABSTRACT Low-mass stars like our Sun begin their evolution within cold (10 K) and dense (∼105 cm−3) cores of gas and dust. The physical structure of starless cores is best probed by thermal emission of dust grains. We present a high-resolution dust continuum study of the starless cores in the B10 region of the Taurus Molecular Cloud. New observations at 1.2 and 2.0 mm (12 and 18 arcsec resolution) with the NIKA2 instrument on the IRAM 30m have probed the inner regions of 14 low-mass starless cores. We perform sophisticated 3D radiative transfer modelling for each of these cores through the radiative transfer framework pandora, which utilizes RADMC-3D. Model best-fits constrain each cores’ central density, density slope, aspect ratio, opacity, and interstellar radiation field strength. These ‘typical’ cores in B10 span central densities from 5 × 104 to 1 × 106 cm−3, with a mean value of 2.6 × 105 cm−3. We find the dust opacity laws assumed in the 3D modelling, as well as the estimates from Herschel, have dust emissivity indices, β’s, on the lower end of the distribution constrained directly from the NIKA2 maps, which averages to β = 2.01 ± 0.48. From our 3D density structures and archival NH3 data, we perform a self-consistent virial analysis to assess each core’s stability. Ignoring magnetic field contributions, we find nine out of the 14 cores (64 per cent) are either in virial equilibrium or are bound by gravity and external pressure. To push the bounded cores back to equilibrium, an effective magnetic field difference of only ∼15 $$\mu$$G is needed.
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- Award ID(s):
- 2205474
- PAR ID:
- 10404115
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 521
- Issue:
- 3
- ISSN:
- 0035-8711
- Format(s):
- Medium: X Size: p. 4579-4597
- Size(s):
- p. 4579-4597
- Sponsoring Org:
- National Science Foundation
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