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Fragmentation and kinematics of the W49N cloud core

1993; IOP Publishing; Volume: 413; Linguagem: Inglês

10.1086/173026

1538-4357

Eugene Serabyn, R. Guêsten, Andreas Schulz,

Atomic and Molecular Physics

view Abstract Citations (60) References (51) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Fragmentation and Kinematics of the W49N Cloud Core Serabyn, E. ; Guesten, R. ; Schulz, A. Abstract A multitransitional study of the W49N molecular cloud core has been carried out in seven rotational lines of CS and C(S-34), ranging in excitation from J = 3-2 to J = 10-9. The cloud core has been found to consist primarily of three dense molecular clumps, of size 0.4-1.0 pc, located approximately along an axis at P.A. 56 deg on the plane of the sky. The clumps' local densities are 2-6 x 10 exp 6/cu cm, and their masses a few 10 exp 4 solar masses each, yielding a total core mass of about 10 exp 5 solar masses. The two outer clumps are receding from us at an LSR velocity of 12 km/s, but the central clump is instead moving away at only 4 km/s, indicating that two different molecular clouds are present toward W49A. Absorption studies place the 12 km/s gas closer to us than the 4 km/s gas, implying that these two molecular clouds are converging upon each other. In addition, the central CS clump is found to be spinning rapidly in a direction counter both to Galactic rotation and to the direction inferred earlier from recombination line observations of the W49A compact H II regions. The hypothesis of global molecular cloud collapse is inconsistent with our new molecular line data. Instead, the molecular gas kinematics suggest that the enhanced O-star formation rate in W49N has been triggered by a cloud-cloud collision. Publication: The Astrophysical Journal Pub Date: August 1993 DOI: 10.1086/173026 Bibcode: 1993ApJ...413..571S Keywords: Mass Distribution; Molecular Clouds; Molecular Spectra; Star Formation; Astronomical Models; Astronomical Spectroscopy; Electron Transitions; Emission Spectra; Astrophysics; ISM: INDIVIDUAL ALPHANUMERIC: W49; ISM: KINEMATICS AND DYNAMICS; ISM: MOLECULES; RADIO LINES: ISM; STARS: FORMATION full text sources ADS | data products SIMBAD (3)