ASTE CO (3–2) MAPPING TOWARD THE WHOLE OPTICAL DISK OF M 83: PROPERTIES OF INTER-ARM GIANT MOLECULAR-CLOUD ASSOCIATIONS
ASTE CO (3–2) MAPPING TOWARD THE WHOLE OPTICAL DISK OF M 83: PROPERTIES OF INTER-ARM GIANT MOLECULAR-CLOUD ASSOCIATIONS
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ASTE CO (3-2) 映射到 M 83 的整个光盘：臂间巨分子云缔合的性质
DOI：
10.1088/0004-637x/706/2/1213
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
R. Kawabe
中科院分区：
文献类型：
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作者：
K. Muraoka;K. Kohno;T. Tosaki;N. Kuno;K. Nakanishi;K. Sorai;T. Sawada;Kunihiko Tanaka;T. Handa;M. Fukuhara;H. Ezawa;R. Kawabe
利用阿塔卡玛亚毫米波望远镜实验，在25″的有效分辨率下，对邻近棒旋星系M83的8′ × 8′（或4.5Mpc时的10.5 × 10.5kpc）区域进行了CO（J = 3-2）谱线辐射的实时成像.由于其非常高的灵敏度，我们的CO（J = 3 − 2）图不仅可以描绘螺旋臂结构，还可以描绘在臂间区域延伸的spur-like亚结构。CO（J = 3-2）辐射中的这一毛刺状亚结构与Hα光度和Spitzer/红外线列阵相机8 μm辐射追踪的大质量恒星形成区的分布相吻合。我们已经确定了54 CO（J = 3-2）块巨分子云协会（GMAs）采用CLUMPFIND算法，并获得了它们的大小，速度色散，维里质量，和CO光度质量。我们发现，对于旋臂中的GMAs，维里参数α（定义为维里质量与CO光度质量的比值）几乎为1，而在旋臂间区域则存在α为3-10的GMAs。我们发现，具有较高α的GMAs往往与大质量恒星形成区无关，而其他维里化的GMAs则与之相关。由于α主要取决于GMA的速度色散，我们假设在这些具有较高α的非维里化GMA中，由于剪切运动，巨分子云内部速度色散的增加抑制了星星的形成。
We present a new on-the-fly mapping of CO (J = 3–2) line emission with the Atacama Submillimeter Telescope Experiment toward the 8′ × 8′ (or 10.5 × 10.5 kpc at the distance of 4.5 Mpc) region of the nearby barred spiral galaxy M 83 at an effective resolution of 25″. Due to its very high sensitivity, our CO (J = 3 − 2) map can depict not only spiral arm structures but also spur-like substructures extended in inter-arm regions. This spur-like substructures in CO (J = 3–2) emission are well coincident with the distribution of massive star-forming regions traced by Hα luminosity and Spitzer/Infrared Array Camera 8 μm emission. We have identified 54 CO (J = 3–2) clumps as Giant Molecular-cloud Associations (GMAs) employing the CLUMPFIND algorithm, and have obtained their sizes, velocity dispersions, virial masses, and CO luminosity masses. We found that the virial parameter α, which is defined as the ratio of the virial mass to the CO luminosity mass, is almost unity for GMAs in spiral arms, whereas there exist some GMAs whose α are 3–10 in the inter-arm region. We found that GMAs with higher α tend not to be associated with massive star-forming regions, while other virialized GMAs are. Since α mainly depends on velocity dispersion of the GMA, we suppose that the onset of star formation in these unvirialized GMAs with higher α are suppressed by an increase in internal velocity dispersions of giant molecular clouds within these GMAs due to shear motion.