skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: FRAGMENTATION OF MOLECULAR CLUMPS AND FORMATION OF A PROTOCLUSTER

Abstract

Sufficiently massive clumps of molecular gas collapse under self-gravity and fragment to spawn a cluster of stars that have a range of masses. We investigate observationally the early stages of formation of a stellar cluster in a massive filamentary infrared dark cloud, G28.34+0.06 P1, in the 1.3 mm continuum and spectral line emission using the Atacama Large Millimeter/Submillimeter Array. Sensitive continuum data reveal further fragmentation in five dusty cores at a resolution of several 10{sup 3} AU. Spectral line emission from C{sup 18}O, CH{sub 3}OH, {sup 13}CS, H{sub 2}CO, and N{sub 2}D{sup +} is detected for the first time toward these dense cores. We found that three cores are chemically more evolved as compared with the other two; interestingly, though, all of them are associated with collimated outflows as suggested by evidence from the CO, SiO, CH{sub 3}OH, H{sub 2}CO, and SO emission. The parsec-scale kinematics in exhibit velocity gradients along the filament, consistent with accretion flows toward the clumps and cores. The moderate luminosity and the chemical signatures indicate that the five cores harbor low- to intermediate-mass protostars that likely become massive ones at the end of the accretion. Despite the fact that the mass limit reached by themore » dust continuum sensitivity is 30 times lower than the thermal Jeans mass, there is a lack of a distributed low-mass protostellar population in the clump. Our observations indicate that in a protocluster, low-mass stars form at a later stage after the birth of more massive protostars.« less

Authors:
;  [1]; ;  [2]
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany)
Publication Date:
OSTI Identifier:
22522431
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 804; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON 13; CARBON MONOXIDE; CLOUDS; COMPARATIVE EVALUATIONS; FILAMENTS; FRAGMENTATION; GRAVITATION; JETS; LUMINOSITY; MASS; METHANOL; OXYGEN 18; PROTOSTARS; RESOLUTION; SENSITIVITY; SILICON OXIDES; STAR CLUSTERS; STAR EVOLUTION; STARS

Citation Formats

Zhang, Qizhou, Lu, Xing, Wang, Ke, and Jiménez-Serra, Izaskun, E-mail: qzhang@cfa.harvard.edu. FRAGMENTATION OF MOLECULAR CLUMPS AND FORMATION OF A PROTOCLUSTER. United States: N. p., 2015. Web. doi:10.1088/0004-637X/804/2/141.
Zhang, Qizhou, Lu, Xing, Wang, Ke, & Jiménez-Serra, Izaskun, E-mail: qzhang@cfa.harvard.edu. FRAGMENTATION OF MOLECULAR CLUMPS AND FORMATION OF A PROTOCLUSTER. United States. doi:10.1088/0004-637X/804/2/141.
Zhang, Qizhou, Lu, Xing, Wang, Ke, and Jiménez-Serra, Izaskun, E-mail: qzhang@cfa.harvard.edu. Sun . "FRAGMENTATION OF MOLECULAR CLUMPS AND FORMATION OF A PROTOCLUSTER". United States. doi:10.1088/0004-637X/804/2/141.
@article{osti_22522431,
title = {FRAGMENTATION OF MOLECULAR CLUMPS AND FORMATION OF A PROTOCLUSTER},
author = {Zhang, Qizhou and Lu, Xing and Wang, Ke and Jiménez-Serra, Izaskun, E-mail: qzhang@cfa.harvard.edu},
abstractNote = {Sufficiently massive clumps of molecular gas collapse under self-gravity and fragment to spawn a cluster of stars that have a range of masses. We investigate observationally the early stages of formation of a stellar cluster in a massive filamentary infrared dark cloud, G28.34+0.06 P1, in the 1.3 mm continuum and spectral line emission using the Atacama Large Millimeter/Submillimeter Array. Sensitive continuum data reveal further fragmentation in five dusty cores at a resolution of several 10{sup 3} AU. Spectral line emission from C{sup 18}O, CH{sub 3}OH, {sup 13}CS, H{sub 2}CO, and N{sub 2}D{sup +} is detected for the first time toward these dense cores. We found that three cores are chemically more evolved as compared with the other two; interestingly, though, all of them are associated with collimated outflows as suggested by evidence from the CO, SiO, CH{sub 3}OH, H{sub 2}CO, and SO emission. The parsec-scale kinematics in exhibit velocity gradients along the filament, consistent with accretion flows toward the clumps and cores. The moderate luminosity and the chemical signatures indicate that the five cores harbor low- to intermediate-mass protostars that likely become massive ones at the end of the accretion. Despite the fact that the mass limit reached by the dust continuum sensitivity is 30 times lower than the thermal Jeans mass, there is a lack of a distributed low-mass protostellar population in the clump. Our observations indicate that in a protocluster, low-mass stars form at a later stage after the birth of more massive protostars.},
doi = {10.1088/0004-637X/804/2/141},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 804,
place = {United States},
year = {2015},
month = {5}
}