FRAGMENTATION AT THE EARLIEST PHASE OF MASSIVE STAR FORMATION

Journal Article · Fri May 01 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/696/1/268; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21300745

Qizhou, Zhang; Yang, Wang; Pillai, Thushara; Rathborne, Jill ^[1]

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1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

We present 1.3 mm continuum and spectral line images of two massive molecular clumps P1 and P2 in the G28.34+0.06 region with the Submillimeter Array (SMA). While the two clumps contain masses of 1000 and 880 M {sub sun}, respectively, P1 has a luminosity OF <10{sup 2} L {sub sun}, and a lower gas temperature and smaller line width than P2. Thus, P1 appears to be at a much earlier stage of massive star formation than P2. The high-resolution SMA observations reveal two distinctive cores in P2 with masses of 97 and 49 M {sub sun}, respectively. The 4 GHz spectral bandpass captures line emission from CO isotopologues, SO, CH{sub 3}OH, and CH{sub 3}CN, similar to hot molecular cores harboring massive young stars. The P1 clump, on the other hand, is resolved into five cores along the filament with masses from 22 to 64 M {sub sun} and an average projected separation of 0.19 pc. Except {sup 12}CO, no molecular line emission is detected toward the P1 cores at a 1{sigma} rms of 0.1 K. Since strong {sup 12}CO and C{sup 18}O emissions are seen with the single-dish telescope at a resolution of 11'', the nondetection of these lines with the SMA indicates a depletion factor up to 10{sup 3}. While the spatial resolution of the SMA is better than the expected Jeans length, the masses in P1 cores are much larger than the thermal Jeans mass, indicating the importance of turbulence and/or magnetic fields in cloud fragmentation. The hierarchical structures in the P1 region provide a glimpse of the initial phase of massive star and cluster formation.

• OSTI ID: 21300745
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 696; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ABUNDANCE
ACETONITRILE
CLOUDS
LINE WIDTHS
LUMINOSITY
MAGNETIC FIELDS
MASS
METHANOL
SPATIAL RESOLUTION
STARS
TELESCOPES
TURBULENCE