研究成果藝廊 > 阿塔卡瑪大型毫米及次毫米波陣列計畫(ALMA)

研究成果藝廊

阿塔卡瑪大型毫米及次毫米波陣列計畫(ALMA)

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Giant molecular clouds and star formation in the tidal molecular arm of NGC 4039

圖片來源: Daniel Espada

CO(2-1) integrated intensity map of the newly discovered molecular arm close to NGC4039 (Espada et al. 2012 ApJ, 760L, 25E). The plus signs indicate the clumps.

The Antennae is a nearby (22 Mpc) pair of merging spiral galaxies (NGC 4038 and NGC 4039). It is one of the nearest and youngest examples of a major galaxy merger. An international team led by Daniel Espada from NAOJ and including Alfonso Trejo-Cruz, Edwige Chapillon, Satoko Takahashi and Yu-Nung Su from ASIAA analysed the CO(2-1) and CO(3-2) ALMA science verification data and found a filamentary (<200 pc) tidal arm extending about 3.4 kpc to the south of NGC 4039 and the overlap region, including molecular clumps. The molecular clump masses are 10^6 to 10^7 solar masses. These clumps are distributed in a beads on a string morphology, and the separation between the beads of ~350 pc is in agreement with the theoretical predictions. This separation may represent a characteristic separation between giant molecular clumps/associations. The star formation efficiency is about ten times higher than in normal spirals. This study was published in the Astrophysical Journal (Espada et al. 2012 ApJ, 760L, 25E).