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Title: A Massive Prestellar Clump Hosting No High-mass Cores

Abstract

The infrared dark cloud (IRDC) G028.23-00.19 hosts a massive (1500 M {sub ⊙}), cold (12 K), and 3.6–70 μ m IR dark clump (MM1) that has the potential to form high-mass stars. We observed this prestellar clump candidate with the Submillimeter Array (∼3.″5 resolution) and Jansky Very Large Array (∼2.″1 resolution) in order to characterize the early stages of high-mass star formation and to constrain theoretical models. Dust emission at 1.3 mm wavelength reveals five cores with masses ≤15 M {sub ⊙}. None of the cores currently have the mass reservoir to form a high-mass star in the prestellar phase. If the MM1 clump will ultimately form high-mass stars, its embedded cores must gather a significant amount of additional mass over time. No molecular outflows are detected in the CO (2-1) and SiO (5-4) transitions, suggesting that the SMA cores are starless. By using the NH{sub 3} (1, 1) line, the velocity dispersion of the gas is determined to be transonic or mildly supersonic (Δ V {sub nt}/Δ V {sub th} ∼ 1.1–1.8). The cores are not highly supersonic as some theories of high-mass star formation predict. The embedded cores are four to seven times more massive than the clumpmore » thermal Jeans mass and the most massive core (SMA1) is nine times less massive than the clump turbulent Jeans mass. These values indicate that neither thermal pressure nor turbulent pressure dominates the fragmentation of MM1. The low virial parameters of the cores (0.1–0.5) suggest that they are not in virial equilibrium, unless strong magnetic fields of ∼1–2 mG are present. We discuss high-mass star formation scenarios in a context based on IRDC G028.23-00.19, a study case believed to represent the initial fragmentation of molecular clouds that will form high-mass stars.« less

Authors:
; ;  [1];  [2]; ;  [3];  [4];  [5]
  1. National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
  2. School of Mathematical and Physical Sciences, University of Newcastle, University Drive, Callaghan, NSW 2308 (Australia)
  3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  4. Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago (Chile)
  5. European Southern Observatory (ESO) Headquarters, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany)
Publication Date:
OSTI Identifier:
22663561
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 841; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMMONIA; CARBON; CARBON MONOXIDE; CLOUDS; DISPERSIONS; DUSTS; EMISSION; EQUILIBRIUM; FRAGMENTATION; MAGNETIC FIELDS; MASS; MOLECULES; RESOLUTION; SILICON OXIDES; STARS; VELOCITY; WAVELENGTHS

Citation Formats

Sanhueza, Patricio, Lu, Xing, Tatematsu, Ken’ichi, Jackson, James M., Zhang, Qizhou, Stephens, Ian W., Guzmán, Andrés E., and Wang, Ke, E-mail: patricio.sanhueza@nao.ac.jp. A Massive Prestellar Clump Hosting No High-mass Cores. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6FF8.
Sanhueza, Patricio, Lu, Xing, Tatematsu, Ken’ichi, Jackson, James M., Zhang, Qizhou, Stephens, Ian W., Guzmán, Andrés E., & Wang, Ke, E-mail: patricio.sanhueza@nao.ac.jp. A Massive Prestellar Clump Hosting No High-mass Cores. United States. doi:10.3847/1538-4357/AA6FF8.
Sanhueza, Patricio, Lu, Xing, Tatematsu, Ken’ichi, Jackson, James M., Zhang, Qizhou, Stephens, Ian W., Guzmán, Andrés E., and Wang, Ke, E-mail: patricio.sanhueza@nao.ac.jp. Thu . "A Massive Prestellar Clump Hosting No High-mass Cores". United States. doi:10.3847/1538-4357/AA6FF8.
@article{osti_22663561,
title = {A Massive Prestellar Clump Hosting No High-mass Cores},
author = {Sanhueza, Patricio and Lu, Xing and Tatematsu, Ken’ichi and Jackson, James M. and Zhang, Qizhou and Stephens, Ian W. and Guzmán, Andrés E. and Wang, Ke, E-mail: patricio.sanhueza@nao.ac.jp},
abstractNote = {The infrared dark cloud (IRDC) G028.23-00.19 hosts a massive (1500 M {sub ⊙}), cold (12 K), and 3.6–70 μ m IR dark clump (MM1) that has the potential to form high-mass stars. We observed this prestellar clump candidate with the Submillimeter Array (∼3.″5 resolution) and Jansky Very Large Array (∼2.″1 resolution) in order to characterize the early stages of high-mass star formation and to constrain theoretical models. Dust emission at 1.3 mm wavelength reveals five cores with masses ≤15 M {sub ⊙}. None of the cores currently have the mass reservoir to form a high-mass star in the prestellar phase. If the MM1 clump will ultimately form high-mass stars, its embedded cores must gather a significant amount of additional mass over time. No molecular outflows are detected in the CO (2-1) and SiO (5-4) transitions, suggesting that the SMA cores are starless. By using the NH{sub 3} (1, 1) line, the velocity dispersion of the gas is determined to be transonic or mildly supersonic (Δ V {sub nt}/Δ V {sub th} ∼ 1.1–1.8). The cores are not highly supersonic as some theories of high-mass star formation predict. The embedded cores are four to seven times more massive than the clump thermal Jeans mass and the most massive core (SMA1) is nine times less massive than the clump turbulent Jeans mass. These values indicate that neither thermal pressure nor turbulent pressure dominates the fragmentation of MM1. The low virial parameters of the cores (0.1–0.5) suggest that they are not in virial equilibrium, unless strong magnetic fields of ∼1–2 mG are present. We discuss high-mass star formation scenarios in a context based on IRDC G028.23-00.19, a study case believed to represent the initial fragmentation of molecular clouds that will form high-mass stars.},
doi = {10.3847/1538-4357/AA6FF8},
journal = {Astrophysical Journal},
number = 2,
volume = 841,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}
  • The fate of massive cold clumps, their internal structure, and collapse need to be characterized to understand the initial conditions for the formation of high-mass stars, stellar systems, and the origin of associations and clusters. We explore the onset of star formation in the 75 M {sub sun} SMM1 clump in the region ISOSS J18364-0221 using infrared and (sub-)millimeter observations including interferometry. This contracting clump has fragmented into two compact cores SMM1 North and South of 0.05 pc radius, having masses of 15 and 10 M {sub sun}, and luminosities of 20 L {sub sun} and 180 L {sub sun}.more » SMM1 South harbors a source traced at 24 and 70 {mu}m, drives an energetic molecular outflow, and appears supersonically turbulent at the core center. SMM1 North has no infrared counterparts and shows lower levels of turbulence, but also drives an outflow. Both outflows appear collimated, and parsec-scale near-infrared features probably trace the outflow-powering jets. We derived mass outflow rates of at least 4 x 10{sup -5} M {sub sun} yr{sup -1} and outflow timescales of less than 10{sup 4} yr. Our HCN(1-0) modeling for SMM1 South yielded an infall velocity of 0.14 km s{sup -1} and an estimated mass infall rate of 3 x 10{sup -5} M {sub sun} yr{sup -1}. Both cores may harbor seeds of intermediate- or high-mass stars. We compare the derived core properties with recent simulations of massive core collapse. They are consistent with the very early stages dominated by accretion luminosity.« less
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