GIANT MOLECULAR CLOUDS AND STAR FORMATION IN THE TIDAL MOLECULAR ARM OF NGC 4039

Journal Article · Sat Dec 01 04:00:00 EST 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/760/2/L25· OSTI ID:22078412

Espada, D; Komugi, S; Muller, E; Nakanishi, K; Saito, M; Tatematsu, K; Iguchi, S; Hasegawa, T; Mizuno, N; Iono, D; Kawamura, A; Akiyama, E; Hiramatsu, M; Nagai, H; Miura, R E ^[1]; Matsushita, S ^[2]; Trejo, A; Chapillon, E; Takahashi, S; others, and

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1. National Astronomical Observatory of Japan (NAOJ), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
2. Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura, Santiago 763-0355 (Chile)

The properties of tidally induced arms provide a means to study molecular cloud formation and the subsequent star formation under environmental conditions which, in principle, are different from quasi-stationary spiral arms. We report the properties of a newly discovered molecular gas arm of likely tidal origin at the south of NGC 4039 and the overlap region in the Antennae galaxies, with a resolution of 1.''68 Multiplication-Sign 0.''85, using the Atacama Large Millimeter/submillimeter Array science verification CO(2-1) data. The arm extends 3.4 kpc (34'') and is characterized by widths of {approx}<200 pc (2'') and velocity widths of typically {Delta}V {approx_equal} 10-20 km s{sup -1}. About 10 clumps are strung out along this structure, most of them unresolved, with average surface densities of {Sigma}{sub gas} {approx_equal} 10-100 M{sub Sun} pc{sup -2}, and masses of (1-8) Multiplication-Sign 10{sup 6} M{sub Sun }. These structures resemble the morphology of beads on a string, with an almost equidistant separation between the beads of about 350 pc, which may represent a characteristic separation scale for giant molecular associations. We find that the star formation efficiency at a resolution of 6''(600 pc) is in general a factor of 10 higher than in disk galaxies and other tidal arms and bridges. This arm is linked, based on the distribution and kinematics, to the base of the western spiral arm of NGC 4039, but its morphology is different to that predicted by high-resolution simulations of the Antennae galaxies.

• OSTI ID: 22078412
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 760; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANTENNAS
CARBON OXIDES
CLOUDS
COMPUTERIZED SIMULATION
DENSITY
EFFICIENCY
GALAXIES
MASS
MORPHOLOGY
RESOLUTION
STARS
VELOCITY