Molecular Gas and Dust in Arp 94: The Formation of a Recycled Galaxy in an Interacting System
Molecular Gas and Dust in Arp 94: The Formation of a Recycled Galaxy in an Interacting System
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Arp 94 中的分子气体和尘埃：相互作用系统中循环星系的形成
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
J. Allsopp
中科院分区：
文献类型：
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作者：
U. Lisenfeld;C. Mundell;C. Mundell;E. Schinnerer;P. Appleton;J. Allsopp
我们提出了新的结果，分子气体，尘埃排放，和电离气体在J1023+1952，一个富氢的星系际恒星形成的潮汐矮星系候选人。它位于两个微弱的恒星潮汐流的投影交叉点，这两个潮汐流缠绕在相互作用的星系NGC 3227/6（阿普94）周围。使用IRAM 30米望远镜，在与J1023+1952相关的整个中性氢云范围内检测到12 CO（1-0）和12 CO（2-1）的发射，该区域的大小为8.9 × 5.9 kpc。分子气体被发现是丰富的整个H I云，与H 2-H I气体质量比在0.5和1.7之间。斯皮策在3.6、4.5、5.8、8.0、15和24 μm的中红外观测表明，年轻的SF仅限于云的南部。尽管H2和H I柱的密度相对均匀，但年轻的SF只出现在CO和H I的速度色散比云中其他地方（FWHM为80-120 km s−1）低约2倍（FWHM为30-70 km s − 1）的区域。因此，气体的运动学，除了其柱密度，似乎是触发SF的一个关键因素。光学/红外光谱能量分布（SED）和Hα光度测定证实，所有的结都是年轻的。最亮SF区域的光谱学允许我们确定金属丰度[12 + log（O/H）= 8.6 ± 0.2]和消光（AB = 2.4）。这表明J1023+1952是由富含金属的气体组成的，这与它代表一个预先存在的矮星系的假设不一致。相反，它必须是由NGC 3227或NGC 3226在相互作用的前一阶段排出的再循环的富含金属的气体形成的。
We present new results for the molecular gas, dust emission, and the ionized gas in J1023+1952, an H I-rich intergalactic star-forming tidal dwarf galaxy candidate. It is located at the projected intersection of two faint stellar tidal streams wrapped around the interacting pair of galaxies NGC 3227/6 (Arp 94). Using the IRAM 30 m telescope, emission from 12CO (1–0) and 12CO (2–1) was detected across the entire extent of the neutral hydrogen cloud associated with J1023+1952, a region of the size of 8.9 × 5.9 kpc. The molecular gas is found to be abundant over the entire H I cloud, with H2-to-H I gas mass ratios between 0.5 and 1.7. New Spitzer mid-infrared observations at 3.6, 4.5, 5.8, 8.0, 15, and 24 μm show that young SF is restricted to the southern part of the cloud. Despite the relatively uniform H2 and H I column density across the cloud, young SF occurs only in those regions where the velocity dispersion in the CO and H I is a factor of ~2 lower (FWHM of 30-70 km s−1) than elsewhere in the cloud (FWHM of 80-120 km s−1). Thus, the kinematics of the gas, in addition to its column density, seems to be a crucial factor in triggering SF. Optical/infrared spectral energy distributions (SEDs) and Hα photometry confirm that all the knots are young. Optical spectroscopy of the brightest SF region allowed us to determine the metallicity [12 + log (O/H) = 8.6 ± 0.2] and the extinction (AB = 2.4). This shows that J1023+1952 is made from metal-enriched gas which is inconsistent with the hypothesis that it represents a preexisting dwarf galaxy. Instead, it must be formed from recycled, metal-enriched gas, expelled from NGC 3227 or NGC 3226 in a previous phase of the interaction.
影响因子：
6.5
作者：
M. Boquien;P. Duc;J. Braine;E. Brinks;U. Lisenfeld;V. Charmandaris
通讯作者：
M. Boquien;P. Duc;J. Braine;E. Brinks;U. Lisenfeld;V. Charmandaris